COMPATIBLE PLANTS         Under & Around Oaks  PUBLISHED BY THE CALIFORNIA OAK FOUNDATION                       Principal ...
PUBLISHER’S NOTE                                                                                         CONTENTSThe Calif...
INTRODUCTION                                                         APPROPRIATE LANDSCAPINGThe distinctive and enduring o...
Native bunch grasses, which naturally grow under oaks, and otherornamental grasses are becoming increasingly popular. Unli...
Guidelines For Tree Protection                                                            Figure 1                        ...
DISEASES: When growing under natural, undisturbed conditions, native              4. Leave the root-crown exposed. If nece...
Treatment for oak root fungus is similar to that for crown rot, however,        removed, or where there is extensive lands...
during decomposition. Be careful not to place the mulch directly againstthe trunk. Organic mulch improves soil structure, ...
GUIDELINES FOR IRRIGATION AND FERTILIZATION                                                      Figure 2                 ...
USING THE PLANT SELECTION CHARTS                                       USING THE PLANT SELECTION CHARTSCN after the plant ...
Shrubs                                                                                                     Important      ...
Shrubs                                                                                                      Important     ...
Shrubs                                                                                                   Important        ...
Shrubs                                                                                                    Important       ...
Shrubs                                                                                               Important            ...
Shrubs                                                                                                      Important     ...
Shrubs                                                                                                    Important       ...
Shrubs                                                                                                      Important     ...
Compatible Plants Under and Around Oaks
Compatible Plants Under and Around Oaks
Compatible Plants Under and Around Oaks
Compatible Plants Under and Around Oaks
Compatible Plants Under and Around Oaks
Compatible Plants Under and Around Oaks
Compatible Plants Under and Around Oaks
Compatible Plants Under and Around Oaks
Compatible Plants Under and Around Oaks
Compatible Plants Under and Around Oaks
Compatible Plants Under and Around Oaks
Compatible Plants Under and Around Oaks
Compatible Plants Under and Around Oaks
Compatible Plants Under and Around Oaks
Compatible Plants Under and Around Oaks
Compatible Plants Under and Around Oaks
Compatible Plants Under and Around Oaks
Compatible Plants Under and Around Oaks
Compatible Plants Under and Around Oaks
Compatible Plants Under and Around Oaks
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Compatible Plants Under and Around Oaks

  1. 1. COMPATIBLE PLANTS Under & Around Oaks PUBLISHED BY THE CALIFORNIA OAK FOUNDATION Principal Authors Bruce W. Hagen, California Department of Forestry (ret.)Barrie D. Coate, Horticultural Consultant and Consulting Arborist Keith Oldham, Horticulturalist and Arborist ©1991 by the California Oak Foundation First electronic publishing 2007 Free to All – Not For Resale
  2. 2. PUBLISHER’S NOTE CONTENTSThe California Oak Foundation (COF) continues to dedicate its work toward achievinghealthy and sustainable oak-forested lands to benefit people, wildlife and plants. IntroductionPopulation pressures are negatively affecting the states important oak resources. In theinterest of public information, COFs Board of Directors and Advisors are making this Appropriate Landscapingpopular booklet available to everyone at no cost. Achieving oak sustainability in a fast-growing state will take responsible actions by each of us. Thanks to the many people Oak Rootsover the years who have made this project possible: Ginger Strong, Karen Leigh, FaithBell, Helen Cannen, Larry Miller, Judy Tretheway, Keith Oldham, Flow Fahrenheit, Kate Oaks and Summer WaterGreene, Elizabeth Proctor, Amy Larson, Claudia Cowan, Gary Jones, the SacramentoTree Foundation and Huge Media. DiseasesJanet Cobb, PresidentSummer 2007 Crown Rot Oak Root FungusTECHNICAL REVIEW WateringThe California Oak Foundation greatly appreciates the assistance of the following individuals whoreviewed the technical material:L. R. Costello, U.C. Cooperative Extension FertilizingGary W. Hickman, Farm Advisor, U.C. Cooperative ExtensionThomas J. Huff, Landscape Architect, Cal Trans MulchingNelda Matheny, HortScience, Inc.Doug McCreary, U.C. Integrated Hardwood Range Management Program PruningGary Sandy, Gary Sandy CommunicationsDr. Alex L. Shigo, The Tree ToucherMichael Thilgen, Four Dimensions Landscape Development Using the Plant Selection ChartsTerance Welch, Consulting Arborist Plant ChartsACKNOWLEDGEMENTS ShrubsIllustrations: Loran May, Jeanette E. Needham, and Marya C. Roddis Ground CoversInside design and layout: Flo Fahrenheit, Karen Leigh, and Keith Oldham PerennialsBooklet Coordinator: Karen Leigh Annuals BulbsSPECIAL THANKS . . . Fernsto our book distributors who have agreed to forfeit future profits from the sale of this book in order Vinesto promote public education, free to everyone: American River Conservancy, American RiverNatural History Assn., Artifact Design and Salvage, Bells Books, Berkeley Horticultural Nursery, GrassesCalifornia Native Plant Society, Columbia Nursery, East Bay Nursery, Fort Ross InterpretiveAssn., Friends of the Regional Parks Botanical Garden Book Store, Harmony Farm Supply, NurseriesMendocino Book Company, Mendocino Coast Botanical Gardens, Native Revival Nursery, PointReyes Book Store, Strybing Bookstore, Sonoma Mission Gardens, Theodore Payne Foundation, Seed and Bulb SourcesToyon Books, Tree Living Center, Tree of Life Nursery, U.C. Botanical Garden Book Store, VanWinden’s Pueblo Garden Center, Wild Bird Center, Yerba Buena Nursery, and Ye Old Book Shop. References Places to VisitFifth printing, with revisions, 2007This electronic edition is free to everyone who cares about oaks. Printing for resale by written Additional Resourcespermission from California Oak Foundation only.
  3. 3. INTRODUCTION APPROPRIATE LANDSCAPINGThe distinctive and enduring oak trees scattered across the state’s valleys, Avoid injuring oak roots or altering the soil conditions where they grow,woodlands and foothills have come to symbolize California’s native particularly within the dripline (periphery of foliage). Keep this area relativelylandscape. These trees are admired for their natural beauty, longevity and undisturbed and free of water-demanding ornamental vegetation such asvalue to wildlife and the environment. Despite this admiration and concern lawns, ground covers and shrubs like rhododendrons, azaleas and camellias.for preserving oaks, developers and homeowners often damage trees Do not remove the natural leaf mulch unless there is a serious fire hazard.inadvertently as they build homes and install landscaping around them. This organic material conserves water, provides nutrients, improves soilAlthough tough and resilient, oak trees can be decimated by construction- structure, decreases soil pH and moderates soil temperatures.related injuries and by changes in soil aeration and moisture levels.This book has been prepared to help you landscape appropriately around Although attractive when planted beneath native oaks, the water required byoaks. By recognizing their basic growing requirements and environmental lush, green lawns and ornamental vegetation can kill them. If turf and/ortolerances, you can incorporate existing oaks into your landscape without water-loving ornamentals are present under oaks, discontinue watering thatjeopardizing their health. A list of plants compatible with the environmental portion within the drip zone (inside circumference of the dripline). If this isrequirements of native oaks is provided. While comprehensive, the list of impractical, redesign the turf or planting area and the irrigation system toplants is by no means complete. Preference has been given to plants that are prevent water from hitting the trunk and wetting the soil within at least 10readily available. Proper irrigation practices and tree care tips to maintain tree feet of the tree’s base (root crown). This is the critical zone for root diseases.health are also discussed. Minimize the use of ornamental vegetation under old, established oaks. Keep the area within the dripline as natural and undisturbed as possible. Use plants as accents rather than as ground covers. Extensive landscaping will disturb the root system and compete for available water and minerals. Consequently, supplemental watering and fertilizing may be needed to prevent drought stress and mineral deficiency. Avoid all planting under declining oaks, and allow trees that have sustained construction damage several years to recover before landscaping beneath them. Plant no closer than 10 feet from the trunk (see figure 1). Select plants that will not ultimately grow into or compete with the oak’s lower canopy. Plant taller growing shrubs outside the dripline. Select plants that will tolerate the dry soils and partial shade typically found beneath native oaks during the summer. Many of California’s native plants are well suited to this environment; they are also attractive and pest resistant. These plants are available from nurseries specializing in native plants (see Nurseries). Many exotic species also perform well, and are available at local nurseries. Plant ornamentals requiring full sun outside the dripline.
  4. 4. Native bunch grasses, which naturally grow under oaks, and otherornamental grasses are becoming increasingly popular. Unlike regular OAKS AND SUMMER WATERlawn grasses they require little water and need less maintenance. Their Once established, native oaks seldom require supplemental irrigation toattractive textures and colors allow them to be used as specimen (feature) survive. Still, most oaks, especially those in urban settings, will benefitplants. When massed together, native grasses give the appearance of a from one to several deep waterings during the hot, dry summer whenmeadow, ideal for the establishment of colorful wildflower annuals. drought stress is greatest. However, when the frequency of irrigation exceeds a monthly application, root health and function are likely toPlant bulbs, seeds and container plants during the fall and winter to ensure suffer.their survival. Seeds propagated in flats before planting out in soil aremore likely to survive. If rain is lacking, water these plants twice a week Frequent irrigation displaces much of the oxygen in the soil, producingfor several weeks. Use a drip system or slow running hose to wet the roots unfavorable growing conditions for oaks. This can lead to reduced growthand 4-6 inches of surrounding soil. Thereafter, water twice a month until and vitality, increased susceptibility to insect and disease pests, die-backfall rains begin. The following season, water monthly during the summer, and decline. Oak roots, particularly those originating at the base of the treewetting the soil to a depth and radius of 12 inches around each plant. By (root crown), are quite vulnerable to root pathogens. Although normallythe third season, most of the plants should be well established, requiring inactive in dry soil, common root pathogens proliferate under warm, moistlittle or no additional watering. Avoid root damage from trenching for conditions created when water is frequently applied to the soil during theirrigation systems by placing waterlines and soaker hoses directly on the summer. Root diseases are more severe when soil drainage is restricted assoil surface and covering with mulch. in heavy clay soil, hardpan, and in low areas. OAK ROOTS Frequent summer irrigation near the root crown is likely to cause root decay which, over time, will destroy the roots, kill the tree or cause structural failure. Disease prevention and management involves changingTo properly plant and manage landscaping around trees, especially native or maintaining environmental conditions to favor tree growth, whileoaks, it is important to understand what tree roots do, where they grow, discouraging root diseases. This involves the reduction of plant stressand what they need. Roots support and anchor the tree, absorb water and through judicious watering, appropriate landscaping and proper tree care.minerals, store energy and produce important chemicals. They grow where Avoiding irrigation for lawns and water-loving ornamental vegetationoxygen, water and minerals are most abundant. However, when any of under native oaks helps ensure their health.these factors are deficient or in excess, root function and, ultimately, treehealth may suffer. Contrary to conventional wisdom, young oaks do not adapt to frequent irrigation. Although oaks in turf or irrigation settings often appear healthy,The roots of mature oaks grow predominantly within the upper three feet most become increasingly susceptible to root disease with age. Soilof soil. Most of the roots responsible for the uptake of water and minerals conditions also play a role in disease development. Oaks planted in fastare concentrated within 12 inches of the surface. Few roots grow deeper draining soil may survive frequent irrigation for many years. Newlythan three feet. Much of the root system is contained within the dripline, planted oaks do require frequent and regular irrigation until they arealthough roots typically radiate well beyond it (see figure 1). established, usually two to three years. This fact is often overlooked by people who assume that because oaks are drought tolerant, they don’t needOak roots, like those of most trees, are extremely sensitive to supplemental watering.environmental change (soil compaction, altered soil grade, increasedmoisture, paving, etc.). These changes reduce the soil oxygen, impair rootfunction and create conditions more favorable to root pathogens (diseaseorganisms).
  5. 5. Guidelines For Tree Protection Figure 1 Root Protection Zone Root Disease Critical Zone Adequate root protection is usually The most crucial area is within ten provided by preventing or limiting feet of the trunk. Do not irrigate, impacts within the drip line. plant or disturb the soil in this area. Organic mulches are very beneficial Roots may grow two to three times in this zone. beyond drip line and near the surface. DO DO NOT§ Select appropriate plants § Compact soil with heavy§ Mulch with 2” to 4” of organic matter machinery, vehicles or livestock§ Protect from compaction § Change drainage patterns§ Tunnel through soil for utility line § Raise soil grade installation § Lower soil grade§ If paving is required, use porous paving, § Trench or otherwise cut roots such as brick on sand or gravel § Till
  6. 6. DISEASES: When growing under natural, undisturbed conditions, native 4. Leave the root-crown exposed. If necessary, provide drainage toCalifornia oaks typically resist most diseases. When weakened by prevent water from collecting around the root-crown during thedisturbance and/or improper landscaping and irrigation, they become winter. Cover the excavated area with a grate or decking if it isparticularly susceptible to diseases. Two serious root diseases commonly deep, or if you use the area around the tree.encountered in irrigated settings are Crown Rot and Oak Root Fungus. CAUTION: Trees that have had moist soil around their basesCrown Rot (Phytophthora spp.) often develop decay in the root-crown. Such trees are often structurally weak and prone to fall, even if their tops appearCrown Rot is one of the most common and serious problems of oaks in healthy. Consult a certified arborist to determine their health andresidential landscapes. Caused by a fungus, it is fostered by excess safety.moisture, poor drainage and inadequate soil aeration. 5. Allow turf in the unirrigated area to die and slowly decompose.Symptoms and signs of this disease include: 6. Remove ornamentals that require frequent irrigation.§ decline (general loss of vigor)§ reduced growth 7. Water drought tolerant plants no more than monthly. Hand water§ twig and branch die-back or use a drip system or soaker hose.§ wilting§ chlorotic (yellow) foliage 8. Fertilization usually is not necessary and may encourage the§ sparse and stunted foliage disease or even slow recovery.§ premature leaf drop§ formation of lesions on the bark of large roots and lower trunk Oak Root Fungus (Armillaria mellea) accompanied by oozing of dark or rusty colored fluid. This disease occurs in many oaks throughout California. However,In most cases, people notice the symptoms too late for successful healthy oaks and those growing under natural, undisturbed conditionstreatment. However, if the disease is detected early, steps can be taken to typically resist damage. Oaks weakened by root loss, drought, defoliation,save the tree. Treatment is best left to a certified arborist as homeowners over pruning, soil compaction, pavement, impeded drainage, fill soilare seldom equipped to deal with these problems. If a specialist cannot be and/or frequent summer irrigation are most susceptible. Once thecalled in, the following measures may be of benefit: symptoms of this disease become obvious there may be little that can be done. 1. Stop all frequent (more than once a month) watering within the drip zone or, at the very least, within ten feet of the trunk. Cap or Symptoms and signs of this disease are similar to those of crown rot: adjust sprinklers as necessary. § gradual die-back or sudden death § twig and branch die-back 2. Remove any soil, mulch or debris that has been placed or has § chlorotic (yellow) foliage accumulated against the trunk above the natural soil line. § premature leaf drop § occasional presence of clumps of honey-colored mushrooms at the 3. If fill soil has been placed around the tree, expose the tree’s flared base of the tree in the fall base (root-crown) at the original soil line. By careful excavation of § white, fan-shaped fungal growth between the bark and wood the soil the buried bark can dry. Remove soil within about one foot § dead bark of the trunk and down until the large, buttress roots are exposed. § wet, stringy, decayed wood § presence of black, root-like structures (rhizomorphs) on the root and in the surrounding soil
  7. 7. Treatment for oak root fungus is similar to that for crown rot, however, removed, or where there is extensive landscaping may benefit fromprevention is the best approach. The key is to keep oaks healthy and periodic light fertilization. Stressed and weakened oaks should not bedisease resistant. Avoid frequent summer irrigation around oaks. Prevent fertilized. Poor growth and appearance are usually the result of poormechanical damage to the major roots, root crown, trunk and branches, growing conditions rather than mineral deficiencies. These problems areand avoid soil compaction within the dripline. Control insect outbreaks exacerbated by fertilizing because it increases top growth at the expense ofbefore serious defoliation occurs, (see University of California Publication root growth. This can result in further weakening of the tree. ImprovingLeaflet 2783, Oaks on the Home Grounds and Leaflet 2542, Oakworm the root environment through mulching, judicious watering, aeration[Oakmoth] and Its Control). Chemical control, e.g., soil fumigants or soil (shallow holes or careful soil loosening) will usually improve tree growth.drenches have not proven effective. Replace disease-killed oaks withresistant tree species, (see University of California Publication Leaflet Young oaks may be fertilized to encourage growth. Mature oaks, on the2591, Resistance and Susceptibility of Certain Plants to Armillaria Root other hand, may be fertilized to maintain health rather than stimulateRot). growth. If the leaves of your tree are dark green and it appears to be healthy, fertilization may be unnecessary. If you suspect a mineralWATERING: Although native oaks usually do not require summer deficiency, consider a soil analysis. Consult your local University ofirrigation, there are several instances when supplemental watering is California Cooperative Extension office for detailed information.appropriate. First and foremost is the need to minimize the effects ofdrought. If the winter is unusually dry, supplemental watering in the When appropriate, apply nitrogen based fertilizer in the late winter to earlyspring can complement natural rainfall. Another reason for the occasional spring when there is rain to carry the water soluble mineral elements intowatering of oaks is when natural water sources have been diverted, e.g., the soil. Nitrogen applied in the fall may gradually dissipate due toextensive pavement, retaining walls, culverts, drains, etc., causing leaching and degradation by soil organisms. As long as it is thoroughlyprecipitation to run off rather than penetrate the soil around the trees. One watered in, nitrogen fertilizer may also be applied in the late spring andfurther very important reason is to reduce stress due to lack of water summer when nitrogen uptake is greatest. Fertilizer is best applied byfollowing moderate to severe root loss from construction injury or broadcasting (spread by hand) over the tree’s root zone (see figure 2). Iftransplanting. rain is lacking, water the minerals into the soil, 6 to 12 inches deep, avoiding the area within 10 feet of the trunk. Use fertilizers such asWater the soil from halfway between the trunk and the dripline to 10 to 15 ammonium sulfate, ammonium nitrate or urea. Complete fertilizersfeet beyond, allowing water to penetrate the soil to a depth of 18 to 24 containing nitrogen (N), phosphorous (P) and potassium (K) are moreinches (see figure 2). It may take 8 to 12 hours to penetrate to this depth. expensive and often unnecessary. If you use a complete fertilizer, selectApply additional watering 1 to 2 times during dry summers. Keep water one with a N-P-K ratio of 3-1-1 or 3-1-2. Fertilize healthy, mature oaksat least 10 feet from the trunk. The length of time for irrigation will vary sparingly, e.g., 1 to 2 pounds actual nitrogen per 1000 square feet ofbased on the rate of water flow, method of irrigation (soaker hose, exposed soil surface every other year, or less frequently. Splitsprinkler, etc.), area covered, rate of water penetration and topography. applications, using 1/2 rate in the late winter and again in the earlyYou may have to experiment a little to get good water penetration. To summer, may be beneficial. Younger trees can be fertilized morecheck the depth of penetration, dig a small hole in the irrigated area 24 frequently and at more moderate rates, e.g., 2 to 4 pounds per 1000 squarehours after watering. If the soil is moist at the desired level, the watering feet of exposed soil surface area.time is adequate. Insufficient watering is marked by dry soil, whileexcessive watering or impaired drainage is indicated by standing water. MULCHING: Keep the soil surface beneath oaks mulched with 2 to 4 inches of organic mulch such as natural leaf-litter, shredded or chippedFERTILIZING: Healthy, mature oaks growing under natural conditions bark, wood chips, etc. To use non-composted material safely, add threenormally do not require supplemental fertilizer (mineral elements). pounds of actual nitrogen per cubic yard of mulch. Otherwise, much ofHowever, oaks in landscaped areas where the leaf-litter is regularly the available nitrogen near the soil surface will be temporarily tied up
  8. 8. during decomposition. Be careful not to place the mulch directly againstthe trunk. Organic mulch improves soil structure, provides minerals upondecay and moderates soil temperatures. Avoid the use of imperviousplastic tarping, which reduces the availability of air and water to the roots.PRUNING: Don’t top oaks to reduce tree height. Instead, prune bycareful thinning to maintain natural shape, health and safety. Rather thanstubbing tree branches, remove the entire branch or cut it back to a branchthat can assume the new lead. Remove no more than 10 to 20 percent ofthe foliage of a healthy, mature oak and even less for an older or decliningone. Don’t make cuts flush to the trunk or branch. The collar or swollenarea at the base of most branches protects the tree from decay. Cut justoutside this collar, leaving it intact without leaving a stub. Wounddressing does not prevent decay and should not be used on pruning cuts.Prune in the late winter, to early spring or early to mid-summer. Dead andweak branches can be removed at anytime. Avoid pruning when theleaves are forming and in the fall. Pruning large trees is both dangerousand difficult; it is best left to professionals. Consult an arborist, preferablysomeone certified by the Western Chapter of the International Society ofArboriculture.
  9. 9. GUIDELINES FOR IRRIGATION AND FERTILIZATION Figure 2 Irrigate and fertilize this area.CRITICAL AREA Irrigate the soil from halfwayKeep this area dry. between the trunk and the driplineDo not irrigate, plant to 10’ to 15’ beyond.or disturb. Keep mulched. Dripline IRRIGATION FERTILIZATIONGenerally, native oaks do not require irrigation. Healthy oaks growing in undisturbed conditions normally do not need supplemental fertilizer.Additional water may be appropriate§ to minimize drought stress Stressed and weakened oaks should not be fertilized.§ when natural water sources have been altered§ after root loss due to construction injury or If needed, broadcast fertilizer in late winter or early transplanting spring when soil is moist and water in.§ to establish compatible plants§ when using fertilizer If fertilizer is applied in summer, irrigate soil before application then water in thoroughly (6” to 12”Do not use sprinkler system; use dripline or soaker deep).hose placed on surface and cover with mulch.Check water infiltration.
  10. 10. USING THE PLANT SELECTION CHARTS USING THE PLANT SELECTION CHARTSCN after the plant name indicates that it is a California Native. Plant ToleranceSome column headings are self-explanatory. P under a column heading indicates the plant will tolerate that condition. Important Characteristics SeacoastFlower Color abbreviations P indicates a plant will grow within 1,000 feet of the ocean where B = Blue Pu = Purple salt air and wind are common. C = Cream R = Red La = Lavender W = White Wind O = Orange Y = Yellow P indicates a plant will tolerate regular winds of 10 miles per hour or P = Pink more.Flower Season abbreviations Hillside (Erosion Control) Sp = Spring Fa = Fall P indicates a plant will tolerate the harsher conditions of hillsides, Su = Summer W = Winter and that the root structure will help prevent soil erosion. DroughtGrowth Rate PP indicates moderate drought tolerance. F = Fast PPP indicates high drought tolerance. M = Moderate S = Slow Deer Susceptibility 1 low susceptibility to deer 2 moderate susceptibility to deer 3 high susceptibility to deer Cultural Preference Deer preferences vary greatly by location and availability ofSun/Part Shade/Dense Shade preferred food plants. If you have experienced problems in theP under the Sun heading indicates the plant prefers sun. past, do a trial planting to see which plants are best for your area.PP under the Part Shade heading indicates the plant prefers partshade. Sunset ZonePPP under the Dense Shade heading indicates the plant prefers dense Refer to Sunset Western Garden Book for a map and definitions ofshade. these zone numbers.Good DrainageP indicates the plant needs good drainage.
  11. 11. Shrubs Important Cultural Plant Characteristics Preference Tolerance Deer Susceptibility Good Drainage Flower Season Dense Shade Sunset Zone Flower Color Growth Rate Part Shade Evergreen Decidious Seacoast Drought Hillside Wind Fruit Sun Berberis darwiniiAbelia grandiflora — Glossy Abelia ü W Su F ü ü ü ü ü 2 5-24Dependable arching form 3’ to 7’. Leaves are shiny, bronze color in spring Pi ü üand fall. A.g. ‘Sherwoodii’ is covered with smaller maroon foliage andreaches 4’ tall. A.g. ‘Prostrata’ is a ground cover.Arbutus unedo — Strawberry Tree ü W Sp ü M ü ü ü ü ü 2 4-24Attractive, reddish, shaggy bark. Forms a good screen up to 25’ tall with an 8’ ü üspread. Plant outside dripline. Red fruit edible, but not tasty. A. unedo üCompacta remains a smaller shrub to 6’ tall.Arctostaphylos densiflora — Manzanita (CN) ü W S ü M ü ü ü ü ü ü 2 7-9A.d. ‘Howard McMinn’ is a reliable, mounding shrub 3’ to 5’ high with a R ü ü 14-21spread of 7’. Attractive, smooth, reddish bark. Olive foliage can be sheared. üGood on hillsides.Berberis darwinii — Darwin’s Barberry ü O Su ü S- ü ü ü ü ü ü 1 1-11Dense mound of dark, glossy leaves, 5’ to 7’ tall. Dark blue berries attract M ü ü 14-17birds. Spiny foliage makes it a good barrier plant. Sprinklers inside foliagewill kill it. Plant at edge of dripline.Buddleia davidii — Butterfly Bush ü Pu Su F ü ü ü ü 1 1-9Grows 10’ to 12’ tall with arching stems. Leaves are 6” long. Flowers are 12” ü ü 12-24long, sweetly fragrant and attractive to butterflies. Prune to 12-18" in winter. üPlant outside dripline.Carpenteria californica — Carpenteria (CN) ü W Sp S ü ü ü 1 5-9Grows to 5’ with dark green leaves and lovely fragrant flowers. Annual ü ü ü 14-24removal of old wood will keep it looking good. Plant at edge of dripline. ü üResistant to oak root fungus.
  12. 12. Shrubs Important Cultural Plant Characteristics Preference Tolerance Deer Susceptibility Good Drainage Flower Season Dense Shade Sunset Zone Flower Color Growth Rate Part Shade Evergreen Decidious Seacoast Drought Hillside Wind Fruit Sun Cercis occidentalisCeanothus ‘Concha’ — Wild Lilac (CN) ü B Sp M- ü ü ü ü ü 2 4-7Shrub 5’ to 7’ tall by 6’ to 8’ wide with characteristic blue flowers. Ceanothus F ü 14-24‘Dark Star’ is similar but is a broader, lower shrub; more disease resistant than ümost ceanothus. Plant at edge of dripline.Ceanothus thyrsiflorus ‘Skylark’ — Ceanothus (CN) ü B Sp F ü ü ü ü ü 3 4-7Forms a dense mounding shrub 4’ to 6’ tall. Flowers are dark blue. C. t. Snow ü 14-24Furry’ has a variable height of 6’ to 12’ and has snow white flowers; plantoutside dripline.Cercis occidentalis — Western Redbud (CN) ü Pu Sp ü F ü ü ü ü ü 2 2-24Multi-stemmed shrub 8’ to 12’ tall. Best outside dripline. Magenta flowers ü übloom before leaves open. Cold winters below 28°F turn foliage rose-red. üResistant to oak root fungus. Plant young.Daphne odorata — Fragrant Daphne ü Pi W S ü ü ü 2 4-9Can be 4’ to 6’ tall with an 8’ spread. Neat, glossy 3” leaves. Sweetly fragrant ü ü 14-24flowers. Needs excellent drainage to prevent water mold attack. D. o.Marginata has leaves with yellow edges.Diplacus hybrids — Monkey Flower (CN) ü Y Su F ü ü ü ü ü ü 1 7-9Grows to 4’ tall and wide. Foliage is narrow and sticky. Best pruned back R ü ü 14-24annually in February to keep compact. Several different hybrids available with ücolor ranges from pale yellow to mahogany red.Eriogonum spp . — Buckwheat (CN) ü Y Su M- ü ü ü ü 1 14-24Several species available. E. arborescens is 3’ to 4’ tall. E. crocatum forms F üan 18” mound with 4” yellow flowers. E. umbellatum polyanthum grows to ü8” tall and 3’ wide.
  13. 13. Shrubs Important Cultural Plant Characteristics Preference Tolerance Deer Susceptibility Good Drainage Flower Season Dense Shade Sunset Zone Flower Color Growth Rate Part Shade Evergreen Decidious Seacoast Drought Hillside Wind Fruit Sun Heteromeles arbutifoliaForsythia x intermedia — Forsythia ü Y W M ü ü ü ü ü 2 2-11Arching branches reach 7’ to 10’ tall. Stiff stems covered with flowers before ü ü 14-16leaf buds open. Branches can be cut for indoor winter bloom. Prune 1/3 of ü 18,19flowering stems to ground after bloom.Garrya elliptica — Coast Silktassel (CN) ü Y Sp ü F ü ü ü ü ü 1 5-9Grows 8’ to 10’ tall with dark green, leathery leaves. Greenish-yellow, 12-14” ü ü 14-21long catkins produced in early spring. Prune to improve shape. Good screen üor hedge, plant outside dripline.Galvezia speciosa — Island Bush Snapdragon (CN) ü R Sp- M- ü ü ü ü ü ü 2- 14-24Shrub 3’ to 5’ across. Tubular flowers attract hummingbirds. Flowers Su F ü ü 3sporadically all summer.Grevillea rosmarinifolia — Rosemary Grevillea ü R Fa- M ü ü ü ü 1 8, 9Forms a dense, dark green shrub 4’ to 5’ tall. Dark green leaves are spiny, C Sp ü 12-24undersides are white. Flowers attract hummingbirds. üHeteromeles arbutifolia — Toyon (CN) ü W Sp- ü M ü ü ü ü ü ü 2 5-24Large shrub 8’ or so, can be pruned to shape and size. Good in a background Su ü üsituation at edge or outside dripline. Red berries attract birds in the fall. üHolodiscus discolor — Ocean Spray (CN) ü W Sp M ü ü ü ü 1 1-7Variable height from 4’ to 15’ depending on conditions. Attracts birds. Good ü ü ü 14-17on hillsides, flowers are fragrant, prune back after flowers fade. ü
  14. 14. Shrubs Important Cultural Plant Characteristics Preference Tolerance Deer Susceptibility Good Drainage Flower Season Dense Shade Sunset Zone Flower Color Growth Rate Part Shade Evergreen Decidious Seacoast Drought Hillside Wind Fruit Sun Myrica californicaIlex cornuta rotunda — Dwarf Chinese Holly ü ü S- ü ü ü ü ü 1 6-15Rounded shrub reaches 3’ tall and wide. Glossy, spiny leaves make it a good M ü ü 17barrier plant. English holly (Ilex aquifolium ) will grow to 30’ unless pruned. üPlant outside dripline.Isomeris arborea — Bladderpod (CN) ü Y All M ü ü ü ü ü 1 AllMounds to 4’ in height. Foliage is ill-scented if bruised. A good plant for year ütough background locations. Native to coastal bluffs and desert washes. üMahonia aquifolium — Oregon Holly Grape (CN) ü Y Sp ü M ü ü ü ü 1 1-21Upright growth 3’ to 6’ tall, with dark green, spiny leaves. M.a. ‘Compacta’ ü ügrows 2’ tall. M. pinnata grows 5’ to 6’ tall. Tolerates sun and drought betterthan M. aquifolium . Resistant to oak root fungus.Myrica californica — Pacific Wax Myrtle (CN) ü M ü ü ü ü ü ü 2 8, 9Upright growth 8’ to 25’ tall. Foliage is glossy green. Makes a good screen or ü ü 14-17hedge or can be pruned into multi-stemmed tree. Plant outside dripline. Mites ümay be a problem.Myrsine africanum — African Box ü M ü ü ü ü ü 1 8, 9Stiff, vertical stems with dark green, small leaves. Will grow to 6’ but can be ü ü 14-17maintained by shearing to any height. Can be used as a formal hedge. üMyrtus communis — Myrtle ü W Su ü M ü ü ü ü 2 8-24Dense rounded shrub 5’ to 8’ with dark green, aromatic leaves. Plant at edge of ü üdripline. Tolerates shearing. M.c. ‘Compacta ’ is 2’ tall and makes a good üformal hedge.
  15. 15. Shrubs Important Cultural Plant Characteristics Preference Tolerance Deer Susceptibility Good Drainage Flower Season Dense Shade Sunset Zone Flower Color Growth Rate Part Shade Evergreen Decidious Seacoast Drought Hillside Wind Fruit Sun Philadelphus virginalisNandina domestica — Heavenly Bamboo ü Pi Sp ü M ü ü ü ü ü 1 5-24Upright form grows to 5. Compound leaves create lacy appearance and showy W ü üfall color of pink to red. Resistant to oak root fungus. Lower growing forms üare N.d. ‘Compacta’ and N.d. ‘Nana’ .Nerium oleander — Oleander ü W Su F ü ü ü ü 1 8-16Frequently used shrub for screen, growing 4’ to 12’ tall depending on cultivar R ü 18-23Long summer bloom in white, pink, salmon or red. Plant at edge or outside üdripline.Ochna serrulata — Mickey Mouse Plant ü Y Su ü S ü ü 2- 14-24Will grow 4’ to 8’ in height and as wide. Leaves are narrow, bronzy in spring ü ü 3turning dark green later. Plant at edge of dripline.Philadelphus virginalis — Mock Orange ü W Sp F ü ü ü 3 1-17Vase shaped, reaching 3’ to 7’ depending on variety. Flowers are delightfully ü üfragrant. Prune 1/3 of oldest canes to 12” after spring bloom.Pinus mugo — Mugho Pine ü ü S ü ü ü ü ü 1 AllForms a neat compact dome to 4’. Dark green needles. Looks good in ü ürock gardens. üPlumbago auriculata — Cape Plumbago ü B Su M ü ü ü 2 8, 9Spreading arch form to 10’ tall. Plant at edge of dripline. Blooms for a ü 12-24long time. Can be damaged by frost. Prune out dead wood. ü
  16. 16. Shrubs Important Cultural Plant Characteristics Preference Tolerance Deer Susceptibility Good Drainage Flower Season Dense Shade Sunset Zone Flower Color Growth Rate Part Shade Evergreen Decidious Seacoast Drought Hillside Wind Fruit Sun Prunus illicifoliaPrunus illicifolia — Holly Leaf Cherry (CN) ü Y W M ü ü ü ü ü 2 2-11Will grow to 15’. Can be pruned to any height. Glossy green, spiny-edged ü ü 14-16leaves. Best used in background as screen or hedge, outside dripline. Resistant ü 18,19to oak root fungus.Prunus lusitanica — Portugal Laurel ü Y Sp ü F ü ü ü ü ü 1 5-9Forms a shrub 6’ to 15’ tall with dark, glossy leaves and dark purple berries ü ü 14-21in summer. Plant outside dripline. Prune to shape. üPunica granatum ‘Wonderful’ — Pomegranate ü R Sp- M- ü ü ü ü ü ü 2- 14-24Vase shaped shrub to 10’ tall with glossy, narrow leaves. Does not fruit well Su F ü ü 3in low water situations. Plant outside dripline. Dwarf forms will reach 1-1/2-3’tall, with small inedible fruit.Rhamnus californica — Coffee Berry (CN) ü R Fa- M ü ü ü ü 1 8, 9Variable height from 3’ to 15’. Flowers aic inconspicuous but berries turn from C Sp ü 12-24green to red to black. R.c. ‘Eve Case’ is more compact, growing 4’ to 8’ tall, üwith lighter leaves. Plant at edge of dripline.Rhus integrifolia — Lemonade Berry (CN) ü W Sp- ü M ü ü ü ü ü ü 2 5-24Another good screen plant 4’ to 10’ tall. Tolerates shearing. The fruit can be Su ü üused to flavor drinks. Plant at edge or outside dripline. R. ovata (Sugar Bush) üis similar, but will do better in inland areas.Ribes sanguineum — Flowering Current (CN) ü W Sp M ü ü ü ü 1 1-7Upright form, variable height 3’ to 10’ tall. Distinctive smell to flowers in ü ü ü 14-17spring, followed by black berries. White fly can be a problem. ü
  17. 17. Shrubs Important Cultural Plant Characteristics Preference Tolerance Deer Susceptibility Good Drainage Flower Season Dense Shade Sunset Zone Flower Color Growth Rate Part Shade Evergreen Decidious Seacoast Drought Hillside Wind Fruit Sun Sarcoccoca ruscifoliaRibes speciosum — Fuchsia Gooseberry (CN) ü ü R Sp ü M ü ü ü ü 1 8, 9Spiny branches 3’ to 6’ long. Red, tubular flowers make it attractive to ü ü 14-24hummingbirds. Will lose leaves in summer, but with a little extra water will be ünearly evergreen.Rosa californica — California Wild Rose (CN) ü Pi Sp ü M ü ü 1 14-16Grows to 4’ in height. Stems are spiny. Flowers are pink and sweetly fragrant, ü üfollowed by colorful red hips. Attracts birds. üSalvia clevelandii — Cleveland Sage (CN) ü B Sp- F ü ü ü ü ü 2 10-24Open shrub to 4’ with gray-green, aromatic leaves. ‘Aromas’ has blue-violet Su ü üflowers. Prune old flower clusters to extend flowering. üSalvia greggii — Autumn Sage ü R Su F ü ü ü ü 1 8-24Upright growth 4’ to 6’ tall. Rosy-red flowers held in loose clusters. ü üLeaves 1/2” to 1”, medium green. Foliage can be sheared into a hedge.Sarcoccoca ruscifolia — Fragrant Sarcoccoca ü W Sp ü S- ü ü ü 1 14-24Grows to 6’ but usually less. Glossy leaves. Fragrant, inconspicuous flowers M ü ü üare delightful cut and used indoors. Flowers followed by red fruit. ü üS. hookerana humilis is a low ground cover form reaching 18”.Syringa vulgaris — Lilac ü W Sp S ü ü ü 1 1-12Will reach 15’ but can be kept smaller by pruning. Flowers are sweetly La ü ü 14-18fragrant. In mild winter areas use one of the Descanso hybrids such as Pu‘Lavender Lady’. Best planted outside dripline.
  18. 18. Shrubs Important Cultural Plant Characteristics Preference Tolerance Deer Susceptibility Good Drainage Flower Season Dense Shade Sunset Zone Flower Color Growth Rate Part Shade Evergreen Decidious Seacoast Drought Hillside Wind Fruit Sun Viburnum tinusTeucrium fruticans — Bush Germander ü B All F ü ü ü ü ü 1 4-24Will reach 4’ to 8’ tall and as wide. Attractive silver-gray foliage, blue Year ü üflowers bloom most of year. Needs to be pruned in spring to maintain üa neat shape.Viburnum suspensum — Sandankwa Viburnum ü W Sp ü M ü ü ü ü 1 15-24Grows to 10’ tall but can be pruned or sheared to any size. Dark green leaves. ü ü üFlowers are inconspicuous and fruit is not long lasting. Makes a good screen. üNeeds good air circulation to prevent pest problems.Viburnum tinus — Laurestinus ü W W- M-F ü ü ü ü 2 14-23Variable height depending on cultivar from 3’ to 20’. V.t. ‘Spring bouquet’ Sp ü üreaches 6’. Foliage is dark green with large 2” to 3” flower clusters.V.t. ‘Dwarf’ grows 3’ to 5’ tall.Xylosma congestum — Xylosma ü F ü ü ü ü 2 8-24Fast growing 15’ to 20’ tall. Best used outside dripline. X.c ‘Compacta’ grows ü3’ to 5’ tall. Dense domed form. Light, golden- green leaves with some spines. üTolerates tough location.Native ShrubsAdditional native shrubs or trees that should be used outside the driplineinclude: Aesculus californica, Cercocarpus betuloides, Fremontodendroncalifornican and Sambucus caerulea .
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