Review

No. 49 WINTER 2005

“CAST-IRON” PLANTS Adaptable Ornamentals for Central Valley Gardens Ellen Zagory, Director of Horticulture, and Warren G. Roberts, Superintendent

YEAR-ROUND VALLEY GARDENING

Gardeners mov- fall and early winter and blooms starting ing to the Central in February and continuing through Valley of California, March and April. Freesias, daffodils and especially those from iris are vigorous in our climate and natu- “back east” states with ralize to return year after year. In shady continental climates areas, cyclamen, summer snowfl ake and summer rain, fi nd (Leucojum aestivum) and Spanish squill themselves confronted (Hyacinthoides hispanica) are reliable with an entirely new winter features that reward with spring set of options for bloom. creating a garden. Summer gardening brings the chal- New Valley gardeners lenge of dry heat, wind and high light discover quickly that intensity. Plants with small leaves, suc-

Ryan Deering we can garden twelve culents, and spiky plants like yuccas and months of the year. agaves have leaves adapted to low hu- Spiky plants like yuccas add a Colorful shrubs like midity and high solar radiation. “Sculp- strong architectural statement winged euonymus and tural” plants like coral yucca (Hesperaloe to the garden and require little ornamental grasses add parvifl ora) can be placed to create focal water or maintenance. a long fall season of points and winter structure. interest to the garden. IN THIS ISSUE In addition, winters in What about herbaceous perenni- “Cast-iron” plants ...... 1 the Central Valley are mild enough to grow cool als—plants that die to the ground in Wildlife update ...... 4 season annuals like sweet peas, pansies, larkspurs, the winter? Adapted to evade freezing Digital mapping grant ...... 4 poppies and lupines and winter vegetables like winters, here in the Central Valley these Friends work groups ...... 5 kale, Swiss chard and lettuce. plants die to the ground or to a small Staff news ...... 5 mat and can cause our gardens to “dis- Summer dormant perennial plants, like Al- Calendar ...... 6 appear” in winter. For the twelve-month stroemeria, add to the fall and winter garden when Horticulture survey ...... 7 gardener they need to be combined with they leaf out at the fi rst sign of cooler weather and Pinkerton Prize ...... 7 evergreen, structural plants. short days. Many bulbs have leaves emerging in the Memberships & gifts ...... 8 Directorʼs letter ...... 10 RIGHT PLANT, purpleblow maple. For orange lovers, rigens, is an adaptable native grass that is the calamondin, × Citrofortunella mi- tough in full sun, yet still makes a visual RIGHT PLACE crocarpa, is a tough plant with beauti- statement in partial shade. Ornamental Probably the hardest part of ful little orange fruits, good for their quince is another tough and adaptable gardening anywhere is knowing ex- lime-like juice or for making jams and plant that fl owers best in full sun but actly what plant will do well in which jellies. For smaller yards that require will also tolerate part shade. January environmental conditions. Some small trees, the Washington hawthorn, fl owers to decorate your table at Chinese plants prefer sun, others shade. With New Year are the reward for growing this an understanding of the orientation plant. of the garden to the four points of the compass you can take advantage of mi- croclimates around buildings. Morn- SPIKY PLANTS AND ing sun is the coolest sunshine and is GRASSES gentle on plants. Eastern exposure is a We are very lucky in the Central good location for delicate plants that Valley that we can grow many spiky burn in our hot summer afternoon and architectural plants that provide sun. Southern and western exposures, evergreen forms for the winter garden where a plant gets sunshine in the season. Agaves, nolinas and yuccas are middle of the day in summer, are suit- well-adapted to dry heat, and many will able for only the toughest plants, but also tolerate winter moisture in heavy a strategically placed tree can provide soils. Agave parryi var. huachucensis is a respite in mid-day and expand your one favorite, resembling a cabbage in its plant choices. Crataegus phaenopyrum, is a tough rounded form and leaves. Yucca fi lamen- If you like to grow tender plants plant with beautiful orange-red fruit in tosa is also hardy, although its tolerance in containers, take advantage of over- autumn and winter. The beautiful and of clay soils still remains to be tested. hangs and south walls to extend the dependable crape myrtle, Lagerstroemia Some of the easiest and most adapt- growing season. Your tender container indica, is another excellent choice. able ornamental grasses are Miscanthus plants will only need to come inside in For large shade trees, consider the sinensis, or eulalia grass, now available the coldest, freezing weather. deciduous Kentucky coffee tree, Gymno- in dwarf forms that allow them to fi t in Some gardeners are uncertain cladus dioica, or the giant valley oak, today’s smaller gardens. Some Pennisetum about the trend toward low-water-use Quercus lobata. A little water to get them forms are beautiful over a long season. landscape designs using California established and occasional summer irri- P. orientale is one of our favorites, with natives and other drought tolerant gation is all they need. For lawn areas, a spring and summer fl owers into fall for plants. Will a favorite garden plant large tree that will absorb air pollution, three seasons of interest. P. alopecuroides be adaptable enough to tolerate these cool the air, provide shade and increase ‘Hameln’ has done well on the Arbo- conditions? One strategy is to organize your property values is the chinquapin retum banks and combines beautifully your garden by “hydrozones,” with oak, Quercus muehlenbergii, a fountain- with Sedum ‘Autumn Joy’. Avoid the the moisture-loving plants close to the shaped tree similar to our lost American invasive Pennisetum setaceum. patio, deck, or wherever you are most elms. active. Then you can place low-water FIND THESE PLANTS AT plants, and irrigate infrequently, in the PLANTS THAT ADAPT TO ARBORETUM SALES areas farthest from activity along the SUN OR HIGH SHADE perimeter of the garden. Many of these adaptable plants Under tall deciduous trees there will be available at the members-only is a special environmental condition Spring Plant Sale and Social on March TOUGH, ADAPTABLE referred to as “high shade.” This al- 12, as well as Arboretum plant sales on TREES lows light to plantings but it is mostly April 2, April 23, and May 14. All sales People who grew up with New indirect, re-radiated and refl ected light take place at the Orchard Park Nursery England autumn color yearn to grow that does not heat up the plant foliage from 9:00 am to 1:00 pm. Bring your maples and birches to capture and as intensely as direct sunlight. Some membership card for the 10% member enjoy the colorful fall season. One plants are amazingly adaptable and discount. Anyone may join at the door. maple that tolerates our water quality can tolerate either high shade or direct and soil condition and still produces sun, as long as they have adequate soil good fall color is Acer truncatum, the moisture. Deer grass, Muhlenbergia

2 UC DAVIS ARBORETUM REVIEW WINTER 2005 CAST-IRON PLANTS FOR THE CENTRAL VALLEY These plants will tolerate a wide range of garden conditions

PLANTS FOR SUN OR PARTIAL SHADE Liriope muscari and cvs. lily turf Muhlenbergia rigens deer grass Liriope spicata and cvs. creeping lily turf Nandina domestica heavenly-bamboo Ophiopogon jaburan and cv. big mondo grass Zephyranthes candida Argentine zephyr lily Ophiopogon japonicus and cvs. mondo grass Artemisia ‘Powis Castle’ Powys Castle wormwood Ophiopogon planiscapus ‘Nigrescens’ black mondo grass Aster, many forms Michaelmas daisy Oxalis purpurea cvs. Cape oxalis Chaenomeles, hybrids and cvs. fl owering quince Sesleria caerulea blue moor grass Erigeron karvinskianus Mexican daisy Mahonia aquifolium Oregon-grape PLANTS FOR FULL SUN Ruellia brittoniana ‘Katie’ dwarf ruellia (with no shade at all) Buxus microphylla cultivars Japanese boxwood Pittosporum tobira and cultivars Japanese pittosporum Grasses & Spiky Succulents Syringa × laciniata cut-leaf lilac Hesperaloe parvifl ora coral yucca Salvia microphylla mint-bush salvia Miscanthus sinensis, ‘Yaku-jima’, dwarf forms of eulalia grass ‘Nippon’, ‘Sarabande’, ‘Silberspinne’ PLANTS FOR SHADE Muhlenbergia dubia Mexican deer grass (will tolerate morning sun with afternoon shade) Pennisetum orientale oriental fountain grass Pennisetum alopercuroides ‘Hameln’ white fountain grass Shrubs Agave parryi var. huachucensis Huachuca agave Brunfelsia paucifl ora cvs. yesterday-today-and-tomorrow Yucca fi lamentosa ‘Gold Edge’ yellow-edged Adam’s needle Buxus microphylla and cvs. Japanese boxwood Calycanthus occidentalis western spicebush Shrubs Camellia sasanqua sasanqua camellia Ceratostigma griffi thii Burmese plumbago Cocculus laurifolius laurel-leaf moonseed Hibiscus syriacus ‘Helene’ white rose-of-Sharon Fatsia japonica Japanese aralia Lagerstroemia indica hybrids and cvs. crape-myrtle Nandina, many cvs. heavenly-bamboo Jasminum nudifl orum winter jasmine Osmanthus fragrans tea-olive Lonicera standishii daphne honeysuckle ‘Laciniata’ lace-leaf staghorn sumac Osmanthus × fortunei hybrid tea olive Rhus typhina Ribes viburnifolium evergreen currant Ribes aureum var. aureum golden currant Sollya heterophylla and cvs. Australian bluebell creeper Rosa, many cvs. and hybrids rose Sarcococca hookeriana var. humilis dwarf sweet box Nerium oleander, dwarf forms dwarf oleander Salvia greggii and hybrids autumn sage Perennials Ajuga reptans ‘Catlin’s Giant’ giant ajuga TOUGH AND ADAPTABLE TREES Arrhenatherum elatius subsp. striped bulbous oat grass Abies nordmanniana Nordmann fi r bulbosum ‘Variegatum’ Acer buergerianum trident maple Bergenia crassifolia winter bergenia Acer truncatum purpleblow maple Carex albula blonde sedge Cedrus deodara Himalayan cedar Carex fl acca (syn. C. glauca) blue sedge × Citrofortunella microcarpa calamondin Carex oshimensis ‘Variegata’ variegated Japanese sedge Crataegus phaenopyrum Washington hawthorn (syn. C. morrowii ‘Variegata’) Crinodendron patagua Chilean lily-of-the-valley tree Carex testacea orange New Zealand sedge Cupressus sempervirens Italian cypress Carex tumulicola Berkeley sedge Diospyros persimmon Ceratostigma plumbaginoides dwarf plumbago Glyptostrobus pensilis Chinese bald-cypress Cyrtomium falcatum Japanese holly fern Gymnocladus dioica Kentucky coffee-tree Erigeron karvinskianus Mexican daisy Koelreuteria elegans subsp. formosana Formosan fl ame tree Festuca glauca blue fescue Lagerstroemia hybrids, tree forms crape myrtle Geranium × cantabrigiense ‘Biokovo’ Biokovo cranesbill Malus ‘Snowdrift’, ‘Spring Snow’ crabapple Helleborus argutifolius Corsican hellebore Pinus canariensis Canary Island pine Helleborus foetidus bear’s-foot hellebore Quercus lobata valley oak Heuchera ‘Canyon Pink’ canyon pink coral bells Quercus virginiana southern live oak Heuchera maxima Island alum root Quercus muehlenbergii chinquapin oak Lamium maculatum cvs. spotted lamium Tilia cordata little-leaf linden Leucojum aestivum summer snowfl ake

UC DAVIS ARBORETUM WINTER 2005 3