A Performance Appraisal of Hardy Bellflowers Hardiness
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5 Plant Evaluation Notes chicago botanic garden 6 Plant Evaluation Notes chicago botanic garden ISSUE 31, 2008 leaves are hairy rather than glossy. Plant Evaluation Notes Top-rated ‘Sarastro’ received the high- Jenny Lee est marks for its compact habit, profusion Carol Freeman Carol Freeman Richard Hawke of violet blue, tubular flowers, and winter Richard Hawke A Performance Appraisal of Hardy Bellflowers hardiness. ‘Sarastro’ was similar to ‘Kent Belle’ in flower but had shorter stems and Richard G. Hawke, Plant Evaluation Manager pubescent leaves. ‘Sarastro’ is a cross be- tween Campanula punctata and C. trache- lue is a much coveted flower color Pink and white extend the range of flower especially in winter months, will cause root lium but has a nonspreading habit. The in the gardening world, and cam- colors beyond blue. Bellflowers common- rot. Fertile soils may encourage too much following hybrids between C. punctata and Bpanulas, or bellflowers, offer a won- ly bloom in late spring and summer and growth for fast-spreading species such as C. latifolia combine tubular flowers with derful palette of blue to fulfill a gardener’s sometimes into autumn. C. glomerata, C. punctata, and C. rapun- the blue color range of C. latifolia. ‘Bur- desire. Their distinctive blossoms come in Bellflowers have characteristically dif- culoides. Deadheading is recommended to ghaltii’ received a poor rating due to low hues of blue and violet, from the deepest ferent basal and stem leaves. Basal leaves encourage rebloom, improve plant health, flower production and significant winter purple to softest gray blue. Furthermore, may be oval, round, lanceolate, or heart- and reduce or eliminate self sowing. Slugs, losses. ‘Stevie Ray’ suffered with foliar an array of plant habits, adaptable to a va- shaped, and are usually larger, long peti- rabbits, and foliar rust can cause health or chlorosis each year, and ‘Van-Houttei’ riety of cultural conditions, ensures there oled, and often toothed. Basal leaves of cosmetic problems for some species. had an inferior habit at times due to floppy is a bellflower for a range of garden uses. some species, such as Campanula carpatica, There are a variety of garden-worthy Campanula punctata ‘Alina’s Double’ Campanula ‘Stevie Ray’ stems when flowering. These cultivars had Campanula takesimana Campanula carpatica ‘Blaue Clips’ Campanula poscharskyana ‘Blue Waterfall’ Campanula is a large, multifarious genus C. glomerata, and C. rotundifolia, wither bellflowers for borders, meadows, and rock similar foliar traits to spotted bellflower in the bellflower family (Campanulaceae), during the flowering period. Stem leaves gardens. Tall bellflowers such as Campan- age, but died during the second summer. (probably a hybrid of C. poscharskyana but were nonspreading. thick carpet of leaves like C. punctata. The Summary of blue and violet. When chosen with with approximately 300 annual, bien- are usually simple, smaller in size, and ei- ula lactiflora and ‘Kent Belle’ are ideal in Much like C. latiloba, root rot due to ex- and C. garganica) to Serbian bellflower in- Campanula rapunculoides was another older crowns tended to die out in winter, At the conclusion of the trial, one half careful thought to climate and site condi- nial, and perennial species native to high ther short stalked or sessile. Foliar color the middle to back of the border, whether cessive soil moisture caused the decline in cluded upturned, star-shaped flowers and a aggressively spreading bellflower. Heavy leaving the younger perimeter shoots that of the bellflowers exhibited good health tions, perennial bellflowers offer gardeners mountains, meadows, or woodlands in ranges from light to dark green with sever- grouped in drifts or paired with other pe- health or outright plant death during sum- low, prostrate habit. The final rating of fair flower production, strong stems, and win- eventually formed a loose mass by the end and vigor, thus demonstrating their adapt- a variety of plant habits for a range of gar- temperate regions of the Northern Hemi- al yellow-leaved forms available. Bellflow- rennials. Campanula carpatica and other mer and winter months. was based on lower flower production and ter hardiness were good attributes; how- of summer. ‘Elizabeth’ was more vigorously ability to the edaphic and environmental den settings. Whether in borders, mead- sphere. Campanula species are most com- ers offer a rich diversity of plant habits, small-sized bellflowers are great choices Plants of Campanula portenschlagiana significant plant losses in one winter. ever, the rhizomatous habit may be too spreading and less open in appearance than conditions of the test site. Among the 32 ows, or rockeries, bellflowers flaunt their monly called bellflowers, although some too—from small, tufted alpine species to for the front of the bed, in rockeries, or (Dalmatian bellflower) were floriferous and Campanula ×pulloides, an interspecific vigorous for most gardens. Shoots of C. the species. ‘Kent Belle’, a hybrid between top-rated bellflowers was ‘Sarastro’, which distinctive bells for many weeks in spring are known as harebells or bluebells. statuesque border plants, and from clump as annualized plants in containers. Low- healthy in summer but plant losses were hybrid between C. pulla and C. carpatica rapunculoides were persistent in the test C. takesimana and C. latifolia, had glossy, received a five-star excellent rating. The and summer. Their flowers are predominately bell- formers to rambling spreaders. growing creepers such as C. poscharskyana recorded each winter. ‘Resholdt’s Variety’ var. turbinata, was represented in the trial garden for five years after the trial ended, heart-shaped leaves and violet blue flowers overall best species for vigor, floriferous- shaped, or campanulate, but can be cup-, Whether grown in full sun or light and C. portenschlagiana make good edging performed similarly to the species except by ‘G.F. Wilson’. Despite good health and and seedlings were observed in multiple reminiscent of ‘Sarastro’. Unfortunately, ness, and hardiness were Campanula glom- References bowl-, tubular-bell-, or star-shaped. The shade, bellflowers are generally easy to plants along walks or beds, and are espe- that no winter losses occurred. Yellow- a compact, tufted habit, the dark purple locations within the test garden during ‘Kent Belle’ was prone to floppiness; stak- erata, C. poscharskyana, C. punctata, C. Lewis, P. and M. Lynch. 1998. Campanulas five floral lobes may be shallow to deeply grow and trouble free in well-drained, cially striking on crannied rock walls. The leaved ‘Aurea’ steadily declined and even- flowers were sparsely produced, and crown and following the trial period. ing is recommended to ensure the best flo- rotundifolia, and C. takesimana; and their A Gardeners Guide. Portland, OR: Timber cut, thus enhancing the cupped, bell, or alkaline soils. Bellflowers do not tolerate spreading habits of C. glomerata, C. punc- tually died during the first summer and was injury was noted in two winters. The lack Campanula rotundifolia (harebell, blue- ral display. ‘Purple Sensation’ was similar cultivars tended to perform equally as well. Press. starry appearance. Flowers are borne singly soggy soils, although some species such as tata, and C. takesimana are appropriate as not retested. Dalmatian bellflower requires of vigor was due in part to competition bell) and ‘Olympica’ were floriferous with to ‘Kent Belle’ but with a bushier, compact These taxa thrived in the test garden and RHS Plant Finder Online. http://www.rhs. or in many-flowered inflorescences, and Campanula lactiflora, C. latifolia, and C. ground covers or for naturalizing but are excellent drainage to grow well; the peri- from the constantly encroaching rhizomes strong habits and plant losses noted in habit. It produced an abundance of dark were not adversely affected by occasionally org.uk/rhsplantfinder/plantfinder.asp. may be upward-facing or nodding in habit. takesimana prefer moist soils. Sodden soils, not well-suited to small or formal gardens. odically wet soils of the test site resulted in of the adjacent C. punctata. one winter only. Campanula rotundifolia purple bells each summer and did not have wet soils. Rice, G., editor-in-chief. 2006. American Campanula lactiflora, C. latifolia, and C. repeated winter losses. ‘Birch Hybrid’ (C. The flowers of Campanula punctata var. alba grew well in one season but died any winter injury. ‘Purple Sensation’ was Unfortunately, a number of taxa did not Horticultural Society Encyclopedia of Peren- takesimana thrive in light shade, making portenschlagiana and C. poscharskyana) had (spotted bellflower) are usually creamy in winter and was not retested. The basal not as prone to floppiness, but flopped flourish and were not successfully estab- nials. New York, NY: DK Publishing, Inc. them perfect choices for transition zones upward-facing, bell-shaped flowers and a white with crimson freckles within the flo- leaves of harebell withered before flower- stems were occasionally observed. lished in the trial. Despite a generally well- between sun and shade. compact spreading habit. Plants of ‘Birch ral tubes, but some newer selections come ing began, and it should be deadheaded Campanula trachelium (nettle-leaved drained soil, periodic soggy conditions Hybrid’ were healthy and floriferous each in shades of purple red. The final ratings after flowering to improve health and the bellflower) was represented in the trial were not conducive to good growth or Wagoner Jen Van The Evaluation Study summer but losses were noted in four of for C. punctata and its cultivars are based ornamental display. by ‘Alba Flore Pleno’ and ‘Bernice’, both long-term establishment of some species. Between 1998 and 2006, the Chicago the six trial winters. on exceptional flower production, good Campanula takesimana was similar in ap- strong stemmed and double flowered. Al- It was almost impossible to grow or over- Botanic Garden (USDA Hardiness Zone The cultivars of Campanula poschar- health, and winter hardiness. Like C. glom- pearance to C. punctata except that it had though both cultivars had moderate foliar winter cultivars of Campanula persicifolia.