RHHSS PLAANNTT TRIALSS BULLLEETIN

Numberr 23 Deccemmberr 2008

Hydrangea paniculata Neiill Lancaster Bottaniisstt,, RHS Garrden Wiisslley

Wendy Weslley Trriiallss Offficerr,, RHS Garrden Wiisslley The RHS Trial of Hydrangea paniculata

Background to the trial H. paniculata in the wild and in Although Hydrangea paniculata has been cultivated in cultivation European gardens for well over a century, for most of that H. paniculata is native of cool temperate and sub-tropical period there has been little choice beyond a handful of regions of Japan, China and Sakhalin, where it grows as a very early introductions. H. paniculata , the panicled deciduous shrub or small tree to 8m in height, at altitudes hydrangea, has invariably played second fiddle to the more to about 1300m. It is often stated to be a very variable colourful H. macrophylla , or hortensia, even though it is species in the wild, but not all authors agree on this. generally easier to grow and more reliably hardy. The first edition of Michael Haworth-Booth’s The Hydrangeas , H. paniculata was first described and named in 1829 by the published in 1950, included over 300 hortensias, but only German physician and botanist Philipp Franz von Siebold 3 types of H. paniculata , namely the cultivars ‘Floribunda’, while working for the Dutch East India Company based on ‘Grandiflora’ and ‘Praecox’. Deshima Island within Nagasaki harbour, Japan. Granted limited access to the mainland to carry out his medical After the 1950s, the range of cultivars started to increase duties, at a time when other foreigners were excluded, with the appearance of the first de Belder introductions Siebold used the opportunity to collect and describe the and slowly gathered pace in the 1970s and 1980s as new native plants, including H. paniculata . Siebold’s generations of seedlings were raised from existing cultivars. determination to explore this closed country eventually Because of the long lead-time for raising and introducing resulted in him falling foul of the authorities and he was new plants, only eight cultivars could be listed in the first banished from Japan before the plant could be exported to edition of the RHS Plant Finder in 1987. A decade on, there Europe. Fortunately, he was allowed to return 30 years were still only twelve cultivars, four of the early de Belder later, when he succeeded in sending back the cultivated selections having become more widely available, but form of H. paniculata now known as ‘Grandiflora’. This subsequent years saw a more rapid increase. In the past 10 cultivar, also known as the pee gee hydrangea, is probably years, interest in H. paniculata has taken off with many still the most widely grown. promising new introductions from breeders in Belgium, Holland, France and the USA. Other early introductions from Japan include ‘Floribunda’, discovered by Carl Maximowicz in a Japanese nursery in With so many new cultivars coming on to the market, the the 1860s, ‘Praecox’, raised from seeds collected on RHS decided to hold a trial to compare the new cultivars Hokkaido Island by Charles Sargent in 1897, and ‘Kyushu’, with the old and to select the best ones for the Award of introduced as a wild-collected seedling from Kyushu Island Garden Merit. More than 40 cultivars were assembled in a by Collingwood Ingram in 1926. trial that was considered by many of those involved to be among the most successful woody plant trials yet In the 1950s, at the embryonic Kalmthout Arboretum and undertaken by the RHS. At the same time, the first Eurotrials later at Hemelrijk, Robert and Jelena de Belder began to were conducted in the UK, France, Germany and Holland, experiment with raising and selecting seedlings of providing an interesting opportunity to compare trial results H. paniculata , derived initially from an old plant in their between different sites and growing conditions. garden of ‘Floribunda’. The first and most famous of these,

Front cover: Hydrangea paniculata ‘Limelight’

Right: Hydrangea paniculata Trial August 2008

2 RHS Plant Trials Bulletin ‘Unique’, was reputedly the sole survivor of a batch of Inflorescence of Hydrangea paniculata young seedlings that had been ravaged by blackbirds. It showing pink late season colour turned out to be an exceptional plant whose offspring yielded many good new cultivars, including ‘Papillon’, ‘White Lace’, PINK DIAMOND , ‘Burgundy Lace’, ‘Brussels Lace’, ‘White Moth’, ‘Green Spire’ and ‘Melody’. Further generations were raised in the 1970s and 1980s by open pollination of these plants, with PINK DIAMOND and ‘White Moth’, in particular, producing some notable cultivars. The arboretum at Hemelrijk still contains many unnamed plants, and seeds from these are still collected and distributed to nurseries in the hope of raising new cultivars.

Breeders in Europe and the USA have built upon the de Belder legacy, producing cultivars with inflorescences of subtly different shapes and shades of pink, white and green, as well as cultivars of more compact habit. Some of the most striking new cultivars have been raised by Peter Zwijnenburg at Boskoop, including ‘Big Ben’, ‘Phantom’, ‘Limelight’, ‘Dolly’, ‘Silver Dollar’ and ‘Pink Lady’, while significant contributions have also come from Darthuizer in the Netherlands and Michael Dirr in the USA.

As a garden plant, H. paniculata has a number of advantages over H. macrophylla . It is relatively drought- tolerant, does well in both full sun and partial shade and grows in acid or alkaline soil, as long as the ground is well- drained. Importantly, it is very hardy (to about -30˚C in the USA) and as it always flowers on the current season’s wood, it is not susceptible to late spring frosts.

Botanical Description Hydrangea paniculata is a deciduous woody plant with serrate leaves arranged in opposite pairs or clusters of three, and flower heads made up of showy, sterile flowers mixed with smaller, fertile flowers. What sets it apart from other species is the structure of the inflorescence, which is typically a cone-shaped panicle. The only other Hydrangea that has flowers arranged in a panicle is H. arborescens and that is distinguished by having lobed leaves.

Habit: In the wild may be a lax shrub to about 2m or a small tree to 8m. Shoots: Somewhat brittle. Downy at first, becoming hairless. Leaves: Elliptic or ovate, serrate, acuminate, rounded or tapered at the base, 7.5 – 15cm long and about half as wide. Arranged in opposite pairs, or in 3’s. Sparsely pubescent above and on the veins below. Flowers: A mixture of small, yellowish fertile flowers and long-lasting (up to about 8 weeks) sterile flowers with 4 or 5 white sepals, usually entire, often ageing to pink or purplish-pink, particularly on the underside. Flowers are borne in panicles on the current season’s growth, opening from the base toward the apex of the panicle. The ovary is semi-inferior. Fruit: A many-seeded capsule. The seeds have no dormancy and typically germinate in 2 to 4 weeks.

Hydrangea paniculata 3 The Trial

Award of Garden Merit (AGM) Objectives ⅷ To compare and assess new and old cultivars Hydrangea paniculata ‘Big Ben’ AGM(H4) 2008 ⅷ To recommend the Award of Garden Merit to those considered to be the best Hydrangea paniculata ‘Floribunda’ AGM H4) 1993* ⅷ To determine correct nomenclature Hydrangea paniculata ‘Grandiflora’ AGM(H4) 1993* ⅷ To obtain specimens, photographs, and descriptions as a Hydrangea paniculata ‘Kyushu’ AGM (H4) 1993 record to be held in the RHS Herbarium at Wisley Hydrangea paniculata ‘Limelight’ PBR AGM(H4) 2008 Hydrangea paniculata ‘Phantom’ AGM(H4) 2008 Records Hydrangea paniculata AGM(H4) 1993 ⅷ Habit PINK DIAMOND ‘Interhydia’ ⅷ Response to pruning Hydrangea paniculata AGM(H4) 2008 ⅷ Stem colour PINKY -W INKY ‘Dvppinky’ PBR ⅷ Foliage colour (summer and autumn) Hydrangea paniculata ‘Silver Dollar’ AGM(H4) 2008 ⅷ Flowering period Hydrangea paniculata ‘Unique’ AGM (H4) 1993* ⅷ Inflorescence shape ⅷ Flower colour (early, mid-season and late season) * Recommended to be rescinded at the AGM Review in 2012 Entries The following will receive an Award of Garden Merit 68 entries, representing 47 cultivars, were submitted by when available to the public gardens, nurserymen and individuals in the UK, Netherlands, Belgium and the USA. Details of each cultivar Hydrangea paniculata ‘Dolly’ are given in the Selection Table below. Hydrangea paniculata ‘Pink Lady’ Cultivation Hardiness rating Three plants of each entry were planted in May 2004. All H4 = hardy throughout the British Isles plants were cut down to the base after planting. The plants were grown in the open, with no shade, and watered only during periods of drought. Soil analyses were conducted Judging Criteria annually and treatments applied as necessary to eliminate nutrient deficiencies and maintain approximately neutral The Woody Plant Trials Subcommittee assessed conditions. entries in the trial for the Award of Garden Merit using the following criteria: ⅷ Habit Pruning ⅷ Bud / Flower / Faded flower All plants were pruned each year in late March. The three plants of each cultivar were used to test three pruning ⅷ Floppiness of head regimes: ⅷ Foliage 1 Hard pruning (to two buds) 2 Moderate pruning (to four buds) 3 Light pruning (removal of previous year’s flowerheads The AGM is only awarded to plants that are: only) ⅷ Excellent for garden decoration ⅷ Available from nurseries ⅷ Reasonably resistant to pests and diseases ⅷ Of good constitution ⅷ Essentially stable in form and colour ⅷ Reasonably easy to grow

Hydrangea paniculata Trial September 2007

4 RHS Plant Trials Bulletin Light Moderate Hard

1 Hard pruning (to two buds)

Where there was a response to pruning, the lightly pruned plants were the first to flower and carried more, smaller flowers than the hard-pruned plants, which flowered later, and bore larger, fewer panicles. Those plants subjected to moderate pruning were intermediate in panicle size and time of flowering. Although the hard-pruned plants tended to grow with added vigour, their larger flowerheads were not always advantageous, sometimes producing panicles that could not be supported and flopped.

February March April

2 Moderate pruning (to four buds)

A further pruning demonstration using spare plants was set up in which three plants of each cultivar were medium- pruned at the end of February, March and April. Delaying pruning was found to delay flowering, as illustrated above.

Both techniques proved to be of interest, the first producing varying bloom size and a flowering delay, the second bringing forward or delaying flowering so as to provide a succession of blooms. Either could be used to extend the period of flowering for group plantings. It may also be worth trying more than one technique on the 3 Light pruning (removal of previous year’s different stems of a single plant, though this was not flowerheads only) attempted during the trial period.

Hydrangea paniculata 5 AGM descriptions

E Hydrangea paniculata ‘Big Ben’ Hydrangea paniculata ‘Floribunda’ M AGM(H4)2008 AGM (H4) 1993* Habit: Upright and slightly spreading, Habit: Upright to spreading, 170 ϫ 180cm. 190 ϫ 210cm. Foliage: Yellow green 146B. Foliage: Dark green 147A, leaves in Stem: Flushed greyed reddish purple whorls of three. 186A, lower stem brown approx. Stem: Pale in upper inflorescence 200D. grading through purplish pink 186A Panicle: Half open, conical and in lower inflorescence to brown 177B tapered. on mature wood. Fertile floret: Pink in bud opening to Panicle: Half open, conical. white. Fertile floret: Buds tipped pink. Sterile floret: Opening pale green Sterile floret: Greyed yellow 160C, approx. 154D, becoming white with a maturing to white NN155A. hint of green, eye white, sometimes Scent: Spicy. L flushed pale pink, maturing to deep Flowering: From late July to early L pink, slightly deeper than186A. September. Scent: Strongly scented. Comments: Slender pointed panicles. Flowering: from early August to mid Will grow into a small tree if unpruned October. but suitable for a small garden with Comments: Outstanding, very free pruning. flowering. Attractive red stems, flower goes off to a good pink. Interesting inflorescence with leaves between the florets. Differences in pruning regime appear to have little impact.

E Hydrangea paniculata ‘Dolly’ Hydrangea paniculata ‘Grandiflora’ E AGM subject to availability AGM (H4)1993* Habit: Upright and spreading, Habit: Sparse and drooping, 165 ϫ 160 cm. 100 ϫ 130cms. Foliage: Yellow green between 137B-C. Foliage: Yellow green, much bluer Stem: Pale green approximately 148C green than 146B. with white lenticels; mature wood Stem: Green 147D flushed 186C in silvery brown mixture of 199A- lower inflorescence, maturing to mid N199C. brown. Panicle: Half open, conical and Panicle: Very dense, conical and tapered. tapered. Upper panicle has numerous Fertile floret: White or creamy green small, pinkish red 47B buds. buds, flowers white, anthers pale Fertile floret: Buds strongly flushed cream. pink 55C, petals white, anthers pink. Sterile floret: Greenish yellow Sterile floret: Lime green 149B, 145A/150C, opening to white with L maturing through greyed yellow 160D L central yellow (paler than 151A) flush. to white with pink bosses. Flowering: From late July to late Sept. Scent: Slightly scented. Comments: Good, undulate, green leaf. Flowering: From end of July to early Delightfully shaped florets of an attractive October. creamy colour in the early stages. Has Comments: Stems have a tendency to huge character. Very impressive, providing flop due to heavy, very dense panicles. a succession of flowers. Improves with age. Not as good as ‘Phantom’.

6 RHS Plant Trials Bulletin E Early season * Recommended to be rescinded at the AGM M Mid-season Review in 2012 L Late season

E Hydrangea paniculata ‘Kyushu’ Hydrangea paniculata ‘Phantom’ E AGM (H4)1993 AGM(H4)2008 Habit: Upright and uneven, Habit: Upright to spreading, 110 ϫ 125cm. 145 ϫ 195cm. Foliage: Yellow green, slightly darker Foliage: Yellow green, a little greener than 146A, glossy. than 146A. Stem: Pale grey green 148D, greener Stem: Green 147D flushed 186A, in leaf axils, lower wood pale brown strongly so in lower inflorescence, after flowering. maturing to mid brown. Panicle: Open, narrow and tapered. Panicle: Very dense, conical and Fertile floret: Buds greenish white, rounded. petals white. Fertile floret: Buds flushed pink, petals Sterile floret: Starting greenish yellow white, anthers pale pink to white. 160D, becoming white 155A lightly Sterile floret: Immature sterile floret tinged buff yellow. Only one sterile greyed yellow 160C, maturing E floret per cluster. through 160D to white with some L Flowering: From mid July to mid florets flushed lime green, deep pink September. at maturity. Some florets with fertile Comments: Flowers early. Good for flowers in centre. small gardens. Very attractive to insects Flowering: From mid July to late having more fertile flowers than many September. others. Responds well to hard pruning, Comments: The stem has great quality, producing the best panicles. Sells well very stiff, supporting panicles well. and looks good in a pot. Sterile florets Performed consistently well throughout remain white. the trial. A marvellous plant which supersedes ‘Grandiflora’. Slightly rounder panicles than ‘Grandiflora’ with a beautiful yellow tip.

PBR E Hydrangea paniculata ‘Limelight’ Hydrangea paniculata PINK DIAMOND E AGM(H4)2008 ‘Interhydia’ Habit: Robust, upright and spreading, AGM (H4)1993 165 ϫ 225cm. Habit: Upright and spreading, Foliage: Yellow green 146A. 155 ϫ 210cm. Stem: Pale grey green 148D, lightly Stem: Red brown in full bloom to blushed pink in places, lower wood brown after flowering. pale brown. Panicle: Dense, broad, conical and Panicle: Very dense, broad, conical tapered. and tapered. Fertile floret: Buds green with pink Fertile floret: Green buds. tips, petals paler than 155A, becoming Sterile floret: Pale lime green, nearest very deep pink in autumn, anthers 150C, then grading through 150D to cream, maturing to pale brown. white, some buds and floret bosses Sterile floret: Paler than 151C, with pink flush; lime green and pink opening to 155A, flushing at margins, L at season end. filling with red-purple 59C in L Flowering: From late mid July to early autumn. October 2008. Flowering: From late July to late Comments: Distinct and outstanding, October. stunning lime green flowers. Medium Comments: Known to be impressive but pruning produces the best effect, not in trial having small panicles and a otherwise large dense florets have a slight greater susceptibility to mineral deficiency tendency to flop. than others. Wonderful late colour, a deep glowing pink.

Hydrangea paniculata 7 E Early season * Recommended to be rescinded at the AGM M Mid-season Review in 2012 L Late season

E Hydrangea paniculata ‘Pink Lady’ Hydrangea paniculata ‘Silver Dollar’ E AGM subject to availability AGM(H4)2008 Habit: Upright to arching, Habit: Upright to moderately 170 ϫ 210cm. spreading, 125 ϫ 165cm. Foliage: Green 147A. Foliage: Yellow green, a little greener Stem: Green in inflorescence, brown than 146A. 177C elsewhere in later season. Stem: White lenticels; lower stem and Panicle: Half open to dense, long with inflorescence axis flushed pink 187D; a rounded top. lower stem turning brown 200D during Fertile floret: Cream bud with pink tip. and after flowering. Sterile floret: Cream maturing to Panicle: Very dense, broadly conical, white, becoming flushed with pink and rounded. 57D at the end of the season. Fertile floret: Very few, cream in bud Flowering: From early July to early then white, perhaps one or two per October 2008. terminal cluster but covered by the L Comments: Distinctive, attractive pink much more numerous sterile florets. L flushing developing around the margin of Sterile floret: Ranging from greyed the cream sterile florets, handsome broad yellow 160B-C to white, some older leaf. Benefits from hard pruning, producing florets with pink tipped bosses, larger panicles than unpruned plant. becoming pink flushed. Scent: Very slight fragrance. Flowering: from mid July to late Sept. Comments: Distinct compact habit and very dense panicle. Sterile florets mature to a good pink. One of the most compact apart from ‘Dharuma’. Strong stems support heavy heads well. Responds well to pruning, resulting in larger panicles and delayed flowering thereby extending the flowering period. Good for small gardens.

E Hydrangea paniculata PINKY -W INKY Hydrangea paniculata ‘Unique’ E ‘Dvppinky’ PBR AGM (H4)1993* AGM(H4)2008 Habit: Upright to slightly sprawling, Habit: Nicely upright to lightly 160 ϫ 175cm. spreading, compact, 140 ϫ 160cm. Foliage: Yellow green 146A, mostly in Foliage: Yellow green, greener than whorls of 3. 146A, petioles flushed dark red. Stem: Pale grey green 148D, strongly Stem: Strongly flushed deep purplish blushed pink in places, especially in red 187C/D, maturing to brown lower inflorescence; lower wood 175A/B. reddish brown. Panicle: Dense, conical and tapered. Panicle: Dense, conical and tapered. Fertile floret: Buds tipped pink, petals Fertile floret: Buds pink 55C, flowers white. white, anthers pink-purple. Sterile floret: Lime green 150C, Sterile floret: Pale lime green, nearest maturing through greyed yellow 160D 151C when immature, then grading L to white with pink bosses, very deep through 150D to white. Floret bosses L pink at the end of the season. and older florets with pink flush. Scent: Spicy. Flowering: From late July to early Flowering: From early August to the October. first week of October. Comments: Did not meet expectations Comments: Very distinct, sturdy and in trial. Much better, older plants can be upright. Good dark red stems and pink seen on Battleston Hill where they have sterile florets at maturity, probably the more well-developed root systems and deepest pink. Responded well to pruning, space. Probably superseded by more displaying the perfect pruning-dependent recent introductions. flowering sequence from unpruned (earliest), to medium and hard pruned (latest). Suitable for small gardens.

8 RHS Plant Trials Bulletin Panicle types Selection table The apparent density of the panicle depends on the ratio of sterile to fertile flowers. Plants in the wild usually have inflorescences with many small, fertile flowers and relatively few sterile flowers, giving the flower heads a delicate appearance similar to a lace-cap. ‘Ammarin’ M Many cultivated forms have a higher proportion of Compact habit, red stems, dense, blunt sterile flowers, making the flower heads denser and panicles. Very distinctive, attractive, showier. The density of the panicle is one of the most white sterile florets, pale pink later. important ornamental characteristics of a cultivar and a Foliage scorch, reflecting sensitivity to feature that, along with the colour changes that may mineral deficiency. Flowering from early take place as the panicle matures, helps to make it August to late September. 150 ϫ 165cm. visually distinctive. Our selection table assigns the Raised and sent by Rein and Mark Bulk panicle density of each cultivar to one of four categories Nursery, 1999. (open, half-open, dense and very dense), according to the ratio of sterile to fertile flowers. This convention was originally introduced during assessment of the Dutch Euro-Trial.

Open <10% sterile flowers, >90% fertile flowers e.g. ‘Kyushu’ ‘Big Ben’ ૽૽૽ M Half open >10% and <50% sterile flowers e.g. ‘Big Ben’ Half-open panicle. Outstanding, Dense >50% and <80% sterile flowers e.g. ‘Dolly’ excellent red stems. Sterile florets go off Very dense >80% to 100% sterile flowers really well to pink. Ideal for the larger e.g. ‘Phantom’ and ‘Limelight’ garden. Flowering from early August to mid October. 170 ϫ 180cm. Raised by Pieter Zwijnenburg Jr, Comparison with other Trials Boskoop, Holland, 1990; sent by Reports from the Dutch and French Eurotrials indicate C R Sanders. that ‘Big Ben’, ‘Limelight’ and ‘Phantom’ were three of the top four performers in both trials. The other top performers in these trials were PINK -W INKY ‘Dvppinky’ and ‘Mega Pearl’. Of these, only ‘Mega Pearl’ did not receive the AGM in the Wisley trial.

‘Bridal Veil’ E Nomenclatural notes An excellent flower arranger’s plant with ‘Burgundy Lace’ huge rounded, dense, blunt panicles There was found to be confusion over the identity of and unusual sterile florets with ‘Burgundy Lace’. Plants from two sources entered as distinctive serrated margins. Stamens ‘Burgundy Lace’ were identified as PINK DIAMOND have comparatively long filaments. Plant ‘Interhydia’, while one that most likely was ‘Burgundy tends to flop badly. Better grown in Lace’ had been entered as ‘Brussels Lace’. A plant entered some shade. Flowering from late June to as ‘Burgundy Lace’ Compact Form was found to be late August. 90 ϫ 130cm. indistinguishable from PINK DIAMOND . The flower heads of Raised in 1975 and sent on behalf of PINK DIAMOND turn a deeper pink than those of ‘Burgundy J de Belder, Kalmthout Arboretum, Lace’. Belgium. A seedling of ‘White Moth’.

‘Webb’s’ ‘Webb’s’, originally known as ‘Webb’s Variety’, was not considered to be distinct from ‘Grandiflora’. ‘Brussels Lace’ ૽૽ E ‘Tardiva’ Distinctive fine florets and half open, Plants from two sources entered as ‘Tardiva’ were noted lacy, tapered panicles; compact habit, to be very similar to ‘Floribunda’, although their true staying white in late season. Different pruning regimes seem to have little identity could not be established. They did not differ effect. Flowering from late July to mid significantly in their panicle characteristics or flowering September. 120 ϫ 160cm. time. Raised in 1975 by R & J de Belder, Kalmthout Arboretum, Belgium; DART ’S LITTLE DOT ‘Darlido’ supplied by RHS Wisley. A seedling of Two entries of DART ’S LITTLE DOT ‘Darlido’ turned out to ‘Unique’. be ‘Harry’s Souvenir’, suggesting that they may have become confused in the trade.

Hydrangea paniculata 9 Selection table

E ‘Burgundy Lace’ ‘Dolly’ ૽૽૽ L Flowering from early August to early Creamy florets gradually develop some October. Open panicle, pink flushed pink in dense panicles resembling fertile floret buds, sterile floret lightly ‘Grandiflora’. Responds well to pruning. flushed with pink as it ages, particularly Medium pruning is thought preferable at margins and veins. No differential as hard pruning produces very large, effects of pruning demonstrated, all heavy heads which tend to flop. plants and panicles an even size. 140 ϫ 165 ϫ 160cm. Flowering from late July 150cm. to late September. Raised by R & J de Belder, Kalmthout Raised by Pieter Zwijnenburg Jr, Arboretum, Belgium in 1975, supplied Boskoop, Holland, 1990; supplied by by the Crown Estate Commissioners. RHS Wisley. See nomenclatural notes. AGM subject to availability.

E ‘Chantilly Lace’ ૽૽ EARLY SENSATION ‘Bulk’ PBR ૽૽ E Good habit and clear white florets Excellent foliage and red stems, ageing to pink on a half open to dense vigorous. A good succession of dense to panicle. Very free flowering, elegant, half open, rounded panicles similar to light and pretty. One plant died from those of ‘Dharuma,‘ providing a long the effects of honey fungus. Flowering lasting display, becoming very deep from early August to late September. pink. Would make an excellent hedge. 140 ϫ 170cm. Flowering from mid June to early October. 145 ϫ 200cm. A seedling of ‘Tardiva’ sent by Michael Dirr, selected by Kay Bowman and Raised c.2004, sent by Rein and Mark Bulk M Dirr, USA. Nursery; ‘Dharuma’ ϫ PINK DIAMOND . Known as QUICKFIRE in the USA.

L DART ’S LITTLE DOT ‘Darlido’ PBR ૽ ‘Everest’ E Most dwarf of all the entries, open Half open panicle, not considered very panicle flowering for a long period, late distinct and a dirty pink as flowers go July to late September. Holds flowers up over. Flowering from mid July to early well and doesn’t need pruning. Good September. Improved by hard pruning front of border plant. Flowering from resulting in better sized panicles. late July to early October. 45 ϫ 105cm. 160 ϫ 190cm. Introduced pre 1995 by Darthuizer Raised at the Sir Harold Hillier Gardens Nurseries. Sent by the raiser. & Arboretum 1989, supplied by RHS Wisley and Crown Estate Commissioners. See nomenclatural notes.

L ‘Dharuma’ ૽૽ ‘Floribunda’ * M Attractive red stems, early and free Elegant, pointed panicles, creamy florets flowering, open to half open panicles, develop some pink as they age. Requires compact, bold foliage. Deep pink sterile pruning to prevent it from becoming florets and fruits at maturity. Slower to too large. Flowering from late July to develop than most, excellent for the small early September. 190 ϫ 210cms. garden. Best left entirely unpruned, it will Introduced by Carl J Maximowicz from naturally reach 1 to 1½m. Flowering from Japan to Botanic Gardens of mid June to early October. 120 ϫ 115cm. St Petersburg in 1890; distributed Imported from Japan, 1989, sent by Rein throughout Europe by R & J de Belder, and Mark Bulk Nursery and C R Sanders. Kalmthout Arboretum, Belgium. Believed to be H. paniculata ϫ Supplied by RHS Wisley and the Crown H. heteromalla resulting in the flattened Estate Commissioners. inflorescence.

10 RHS Plant Trials Bulletin Height and Spread Performance rating: ૽૽૽ Excellent E Early season * Recommended to be Measurements for height The judging scores are ૽૽ Very good rescinded at the AGM and spread relate to the summarised by a Mid-season Review in 2012 ૽ Good M unpruned, approximately performance rating from four year old plant of 0 – 3 stars. none Average to poor, L Late season each entry. or not judged

L ‘Grandiflora’ * Hydrangea paniculata ૽ M Dense panicles cause stems to flop. from Taiwan Superseded by ‘Phantom’. It is better Floriferous, distinctly subtle and dainty, not to prune so as to reduce vigour, open panicles. Combines well with panicle size and the tendency to flop. herbaceous plants and is fantastic for Flowering from the end of August to the butterflies. A good flower arranger’s end of September. 100 ϫ 130cm. plant with attractive red stems. Widely grown in the USA and known as Flowering from mid July to late August. the PG or pee gee hydrangea. 200 ϫ 180cm. Introduced by Philipp von Siebold in One of a number of introductions from 1862 from Japan; sent by the Crown Taiwan by Bleddyn Wynn-Jones, Crûg Estate Commissioners. Farm Plants; sent by Rein and Mark Bulk Nursery.

E ‘Great Escape’ ‘Kyushu’ ૽૽૽ E Tall bush with sturdy branches, narrow, Very attractive to insects as it has more open panicles. No pinking of the sterile fertile florets than many other cultivars. florets. Flowering from mid July to late Open panicle, sterile florets are small and August. 185 ϫ 205cm. remain white. Compact, suiting a small garden but superseded by recent Introduced pre 1995 by Darthuizer introductions. Does well in a pot. Nurseries. Sent by the raiser. Responds well to hard pruning producing attractive panicles. Flowering from mid July to mid September. 110 ϫ 125cm. Introduced by Collingwood Ingram from Kyushu, Japan; distributed through Europe by R & J de Belder, Kalmthout Arboretum, Belgium; sent by the Crown Estate Commissioners.

M ‘Greenspire’ ૽ ‘Limelight’ PBR ૽૽૽ L Vigorous, open to half open panicle. Stunning and very distinctive, very There are many of this style. No pink at dense, lime green panicles ageing maturity. Flowering from late July to late through cream to pink. Excellent glossy September. 200 ϫ 220cm. foliage. Medium pruning is recommended, reducing flopping of Raised by R & J de Belder, 1975, a heavy panicles. Flowering from mid July seedling of ‘Unique’. Supplied by RHS to early October. 165 ϫ 225cm. Wisley and the Crown Estate Commissioners. Raised by Pieter Zwijnenburg Jr, Boskoop, Holland in 1990; sent by RHS Wisley.

E ‘Harry’s Souvenir’ ‘Last Post’ ૽૽ E All nine plants of this cultivar failed to Compact habit, ideal for the smaller survive the trial. Low growing, very garden. Very pretty, beautifully shaped dense panicles. Arching flowering stems sterile florets with attractively reflexed tended to flop. Bright green anthers. sepals on half open panicles which age to pink. Fertile florets pink in bud. Good Raised by the Research Station for red stems. Responds well and improved Nursery Production, Boskoop, Holland; by pruning. Flowering from mid July to named in memory of Harry van de Laar. early October. 110 ϫ 200cm. Sent by Rein and Mark Bulk Nursery and Ward van Teylingen. Introduced in 1999 by Darthuizer Nurseries. Sent by the raiser.

Hydrangea paniculata 11 Selection table

M ‘Martinvast’ ૽૽ ‘National Arboretum’ E Attractive sterile florets with serrated A tall sprawling shrub with brown stems margins on half open panicles and open panicles. Sterile florets ageing becoming lightly flushed with pink in to pale pink. Flowering from mid July to maturity. Compact and free flowering, late September. 140 ϫ 170cm. good foliage. Flowering from mid July to Raised by Pieter Zwijnenburg Jr., late September. 110 ϫ 135cm . Boskoop, Holland; sent by RHS Wisley. Introduced by J de Belder, named after the Parc de Martinvaast, Cherbourg, France; sent by R Mallet.

E ‘Mega Pearl’ ૽ ‘October Bride’ M Pearly sterile florets but rather an open Upright to lightly spreading habit and habit and crowded, half open panicle. open panicle. Flowering from late July to Evidence of foliage scorch. Flowering mid October, until the first frosts. from late July to early October. 195 ϫ 225cm. 135 ϫ 150cm. Raised by R & J de Belder, Kalmthout Raised by Pieter Zwijnenburg Jr, Arboretum, Belgium in 1967; a seedling Boskoop, Holland in 1990; supplied by of ‘Tardiva’; sent by Derby City Parks RHS Wisley. Department.

M ‘Mid Late Summer’ ૽ ‘Papillon’ E Good sturdy plant, very floriferous but Poor, sprawling habit. Open to half crowded, half open panicle goes off to open panicle. ‘Papillon‘, the French pink and ages gracefully. Not as good as word for butterfly, is said to describe the ‘Big Ben’ and similar to ‘Mega Pearl’. shape of the sterile florets, however this Flowering from mid July to early was not obvious in trial. Flowering from October. 200 ϫ 205cm. early August to mid September. 160 ϫ 210cm. Raised by Pieter Zwijnenburg Jr, Boskoop, Holland in 1990; sent by RHS Raised by R & J de Belder, Kalmthout Wisley. Arboretum, Belgium in 1970; sent by Rein and Mark Bulk Nursery.

E ‘Mustila‘ ‘Pee Wee’ E Poor habit and rather thin, attractive red Described as very unique and compact stems. Early, half open panicles. form of the pee gee Hydrangea, Flowering from late June to late ‘Grandiflora’, but it was not impressive September. 125 ϫ 100cm. in trial. The pruning regime resulted in big differences between the three Sent by the Research Station, Boskoop, plants; the back plant was rather gappy, Holland, named in 1998 after the the medium pruned less so with lots of Arboretum Mustila near Elimäki in South new growth and the unpruned plant the Finland founded by A F Tigerstedt in best. However, the dense panicles on 1902. the hard pruned plant went on to flop. Flowering from mid July to early October. 175 ϫ 185cm. Raiser unknown, sent by Rein and Mark Bulk Nursery.

12 RHS Plant Trials Bulletin Height and Spread Performance rating: ૽૽૽ Excellent E Early season * Recommended to be Measurements for height The judging scores are ૽૽ Very good rescinded at the AGM and spread relate to the summarised by a Mid-season Review in 2012 ૽ Good M unpruned, approximately performance rating from four year old plant of 0 – 3 stars. none Average to poor, L Late season each entry. or not judged

L ‘Phantom’ ૽૽૽ ‘Praecox’ ૽૽ E One of the most impressive entries. The A very distinctive flower and lime green stem has great quality, very stiff, early foliage, having substantial impact supporting the very dense panicles well. particularly when unpruned. Free Slightly rounder panicles than flowering and tough. Broad, half open ‘Grandiflora’ with a beautiful yellow tip, panicle with elongated, ovate, sterile denser than ‘Limelight’. It performed florets. Excellent edge of woodland plant consistently well throughout the trial, a that can make a very large specimen. marvellous plant superseding Flowering from late June to mid August; ‘Grandiflora’. Flowering from mid July to the first to flower. 140 ϫ 155cm. late September. 145 ϫ 195cm. Wild collected in Japan by C S Sargent, Raised by Pieter Zwijnenburg Jr, founder of the Arnold Arboretum, USA. Boskoop, Holland in 1990; sent by C Lane, C R Sanders and RHS Wisley.

L PINK DIAMOND ‘Interhydia’ ૽૽૽ ‘Sherwood’ ૽ E This plant showed sensitivity to an Attractive, cupped sterile florets on open apparent mineral deficiency on the trial panicles. Makes a big mound with site, yet is known to perform well, potential to sprawl. Flowering from late without leaf scorch, elsewhere. The late June to late September. 165 ϫ 185cm. season colour was magnificent, the dense Raised and sent by Sherwood Cottage panicles developing a deep, glowing pink Nursery. which made the plants stand out from those around them. Flowering from late July to late October. 155 ϫ 210cm. Raised by R & J de Belder, Kalmthout Arboretum, Belgium in 1980; supplied by RHS Wisley and the Crown Estate Commissioners.

L ‘Pink Lady’ ૽૽૽ ‘Silver Dollar’ ૽૽૽ M Distinctive, attractive pink flushing Compact habit and very dense panicles. developing around the margin of the Sterile florets mature to a good pink. cream sterile floret. Half open to dense One of the most compact apart from panicle, handsome broad leaf. Benefits ‘Dharuma’. Strong stems support heavy from hard pruning, producing larger heads well. Responds well to pruning, panicles than the unpruned plant. resulting in larger panicles and delayed Flowering from early July to early flowering thereby extending the October. 170 ϫ 210cm. flowering period. Good for small gardens. Flowering from mid July to late Raised by Pieter Zwijnenburg Jr, Boskoop, September. 125 ϫ 165cm. Holland in 1990; sent by C R Sanders and RHS Wisley. Raised by Pieter Zwijnenburg Jr, Boskoop, Holland in 1990; supplied by RHS Wisley. AGM subject to availability.

L PINKY -W INKY ‘Dvppinky’ ૽૽૽ ‘Skylight’ ૽૽ E Very distinct, sturdy upright and compact. Excellent half open panicles of very Good dark red stems and pink sterile good quality, clean, white florets. florets at maturity, probably the deepest Demonstrating the greatest difference pink. Responded well to pruning, between the 3 plants, the unpruned displaying the perfect pruning-dependent plant flowering significantly earlier, far flowering sequence from unpruned to ahead of the medium and hard pruned hard pruned. Suitable for small gardens. plants where flowering extends into late Flowering from the middle of July to the October. Flowering from mid July to first week of October. 140 ϫ 160cm. early October. 165 ϫ 230cm. Raised at the Research Station Melle, Raised by Pieter Zwijnenburg Jr, Belgium, 2003; sent by C R Sanders. Boskoop, Holland in 1990; supplied by RHS Wisley.

Hydrangea paniculata 13 Height and Spread Performance rating: ૽૽૽ Excellent E Early season * Recommended to be Measurements for height The judging scores are ૽૽ Very good rescinded at the AGM and spread relate to the summarised by a Mid-season Review in 2012 ૽ Good M unpruned, approximately performance rating from four year old plant of 0 – 3 stars. none Average to poor, L Late season each entry. or not judged

M STARLIGHT FANTASY ‘Degustar’ ૽૽ VANILLE -F RAISE ‘Renhy’ ® ૽૽ L Distinctive sterile floret on half open to Low, spreading shrub. The best red dense panicle. Sinuate leaf and healthy, stem, but an inherent weakness resulted glossy foliage. Late flowering, florets in very dense panicles flopping, the hard maturing to light pink. Flowering from pruned plant holding up best. Appeared mid July to early October. 120 ϫ 130 cm. to be less weatherproof than many, resulting in early browning of the Raised by Frères de Gussem, Belgium, otherwise wonderful, pink, mature PBR applied for. Known in France as sterile florets. 125 ϫ 185cm. Flowering ‘Perle d’Automne’; sent by M Foster. from mid July to early October. Bred by Eric Renault, Pépinières Renault, Gorron, France. Sent by SAPHO.

E ‘Tardiva’ ‘Vera’ ૽ E Flowering from late July to early ‘Brussels Lace’ type, drab foliage, similar October. 135 ϫ 130cm to the wild type. The name probably comes from the Latin word vera , Sent by the Crown Estate Commissioners meaning truth, plants were often and RHS Wisley. described as var. ‘vera’ in the past but it See nomenclatural notes. is not in general use now. Open to half open panicle, flowering from mid July to early September. 140 ϫ 155cm. Raised by de Kort, who preceded the de Belders at Kalmthout Arboretum. Sent by Derby City Parks Department.

M ‘Tender Rose’ ૽ ‘Webb’s’ E A half open panicle, initially displaying a Flowering from the beginning of August nice contrast between pink fertile buds to early October. 135 ϫ 195cm. and white sterile florets which mature to Raised by J A Webb, Huntsville, an unremarkable pale pink. Pruning has Alabama, USA in 2003. Sent by Rein and no marked effect. Flowering from mid Mark Bulk Nursery and RHS Wisley ex July to late September. 115 ϫ 120cm. P Zwijnenburg Jr. Raised by Darthuizer Nurseries before See nomenclatural notes. 1995, selected as a seedling from ‘Kyushu’. Sent by Darthuizer Nurseries.

E ‘Unique’* ૽૽ ‘White Goliath’ E This cultivar did not meet expectations syn. ‘Goliath’ in trial, although much better, older Named for its vigour but is no more plants can be seen on Battleston Hill, vigorous than and is similar to many RHS Wisley Garden. Superseded by others. A medium, upright, spreading more recent introductions. Dense plant with narrow, open panicles, florets panicles, flowering from late July to early flushing pale pink with age. Flowering October. 160 ϫ 175cm. from mid July to mid September. The first introduction of R & J de Belder 170 ϫ 170cm. pre 1970 as a seedling from A chance seedling at Rein and Mark Bulk ‘Floribunda’. Sent by the Crown Estate Nursery, 2000; sent by the raiser. Commissioners and RHS Wisley.

14 RHS Plant Trials Bulletin E ‘White Lace’ Woody Plant Trials Sub-committee Not outstanding or distinctive, only Chairman: Chris Sanders 1 plant of 6 survived the trial. Open Vice-Chairman: John Hillier panicle, flowering from late June to late August. 130 ϫ 185cm. Chris Brickell Peter Catt David Clark Maurice Foster Raised by R & J de Belder, Kalmthout Arboretum, Belgium in 1970; sent by John Gallagher Kevin Hughes C R Sanders and RHS Wisley. Roy Lancaster Michael Hickson John Humphris Chris Lane David Masters Harvey Stephens

Suppliers of Plants to the Trial Jelena de Belder (deceased), Hemelrijk, Essen, Belgium . Rein and Mark Bulk Nursery, Rijneveld 115, 2771 XV Boskoop, The Netherlands. E ‘White Lady’ Crown Estate Commissioners , The Great Park, Windsor, Not represented in the RHS trial, Euro- Berkshire SL4 2HT . trial only. Attractive serrate, sterile Darthuizer Boomkwekerijen Bv, Broekweg 3, 3956 NE floret petals. Half open panicles. Leersum, The Netherlands . Raised by Pieter Zwijnenburg Jr, Derby City Parks Dept, Celtic House, Heritage Gate, Boskoop, Holland, 1990. Friary Street, Derby DE1 1QX . M Dirr, Georgia, USA M Foster, Kent Collection d’Hydrangea Shamrock, Route de l’Eglise76119 Varengeville sur Mer, France. Chris Lane, Witch Hazel Nursery, Callways Lane, Newington, Sittingbourne, Kent ME9 7LU . RHS Garden Wisley, Woking, Surrey GU23 6QB C R Sanders, Staffordshire SAPHO, Les Islettes, 49250, La Menitre, France M ‘White Moth’ ૽ Sherwood Cottage Nursery, Sherwood Cottage, Newton St Cyres, Exeter EX5 5BT . Recommended to be grown in a large garden as a specimen shrub, taking Ward van Teylingen, Goudse Rijweg 326, 2771 BA time to reach its full potential. Boskoop, The Netherlands . Excellent for shade, it glows in reduced light. Half open, rounded panicles. Pruning produces larger blooms with a National Collections of Hydrangea tendency to flop, so better simply Mr P R Smith, Derby City Parks, 15 Stores Road , Derby, deadheaded. Flowering from late June to late August. 195 ϫ 190cm. Derbyshire, DE21 4BD. Tel: 01332 641560 Mrs S Newman, The Lakeland Horticultural Society Raised by R & J de Belder, Kalmthout Garden at Holehird, Patterdale Road, Windermere, Arboretum, Belgium in 1975, supplied Cumbria, LA23 1NP. Tel: 01539 446008 by RHS Wisley. Mr S Wingett, The Garden House, Erbistock, Wrexham, LL13 0DL . Tel: 01978 781149

Further reading: Church, G. 1999. Hydrangeas . Cassell. Dirr, M.A. 2004. Hydrangeas for American Gardens. Timber Press. Haworth-Booth, M. 1984. The Hydrangeas (5th ed.) Constable. Lawson-Hall, T. and Rothera, B. 1995 Hydrangeas A Garden Guide . B.T. Batsford. Mallet, C. 2008. Hortensienatlas . 2008. Ulmer. Van Gelderen, C.J. and Van Gelderen, D.M. 2004. For contact details of nurseries that can supply plants see Encyclopedia of Hydrangeas . Timber Press. RHS Plant Finder , also available online at: www.rhs.org.uk/rhsplantfinder/plantfinder.asp

Hydrangea paniculata 15 RHS Plant Trials The Royal Horticultural Society With so many different types of gardener and so many The RHS is the UK’s leading gardening charity dedicated to different cultivars available to them in each group of advancing horticulture and promoting good gardening. Its plants, it is important that a system of recommendation is charitable work includes providing expert advice and in place to help with selection at point of sale. These information, advancing horticulture, training the next recommendations must be clear and reliable to ensure that generation of gardeners, helping school children learn of the thousands of plants available in the UK, a about plants, and conducting research into plants, pests proportion are known to be excellent garden plants. The and environmental issues affecting gardeners. The RHS RHS provides this information through its extensive AGM plant trial scheme is an important part of this work. programme of plant trials held at RHS gardens in the UK. The RHS Award of Garden Merit signifies the selection The RHS receives no government grants and for every of the best cultivars for general garden use. pound received from members’ subscriptions we need to raise more than twice as much again to fund our charitable RHS plant trials serve the professional gardener who wants work. We also rely on donations and sponsorship to to know the range of plants available, including the latest supplement income from our garden operations, flower breeding and selection programmes, with their distinctive shows, shops and plant centres. characteristics and provenance. They also serve the amateur who wants to know which plants will grow and perform well in a particular garden situation. RHS Herbarium The RHS Herbarium keeps a record of trial cultivars as dried The RHS has an unrivalled resource of knowledge and specimens with detailed descriptions and photographic expertise and is therefore best placed to conduct plant images. This forms an important reference for the trials for the UK gardening market. horticultural industry. Any new cultivars are highlighted and a nomenclatural standard specimen is preserved and described. RHS Trials Bulletins Begonia Rex Cultorum Group: Number 16 The RHS Herbarium, stored at RHS Garden Wisley, is the Canna : Number 3 largest active horticultural herbarium in the world. At Chilli Peppers : Number 22 present the collection contains about 80,000 herbarium Clematis alpina & C. macropetala : Number 21 specimens and over 40,000 images of plants. Material is Daisies (yellow perennial): Number 6 actively collected from a wide spectrum of sources Delphinium : Number 5 including RHS plant trials. Fuchsia (hardy): Number 12 Geranium (hardy) Stage 1: Number 10 Geranium (hardy) Stage 2: Number 14 Geranium (hardy) Stage 3: Number 18 Hyacinthaceae (little blue bulbs): Number 11 The RHS, the UK’s leading gardening charity Hydrangea paniculata : Number 23 Iris (bearded): Number 17 RHS Garden, Wisley Lavenders (hardy): Number 2 Woking Miscanthus : Number 7 Surrey Peppers (sweet): Number 15 GU23 6QB Potatoes (salad): Number 8 e-mail: [email protected] Potentilla (shrubby): Number 1 Rhododendron yakushimanum and hybrids: Number 13 www.rhs.org.uk/trials Runner Beans : Number 19 Saxifrages (silver): Number 9 Reg charity no. 222879 Sedums (herbaceous): Number 20 in Scotland SCO38262 Spiraea japonica (with coloured leaves): Number 4

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ISSN 1477-9153 (print) RHS Plant Trials and Assessments ISSN 1447-9161 (online) Online publications, to complement the RHS Plant Trials Bulletins series Caryopteris: Number 2 Perovskia: Number 3 Printed by Trident Printing (ISO14001) Pittosporum tenuifolium hybrids and cultivars: Number 1 using FSC accredited materials – TT-COC-002508

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