Garden Guide: Acer-Azalea
Acer - Azalea
ACER campestre - Hedge Maple
PLANTING: Plant in full sun or light shade in a well drained but moist soil. MAINTENANCE: Fertilize in early spring and water during periods of dry weather. A mulch of chopped leaves or pine straw would be helpful. Zones 4-8.
ACER japonicum (shirasawanum) - Full Moon Maple
PLANTING: Set plants 10 to 15 feet apart in high shade to partial shade, with protection from the hot afternoon sun in hotter areas. Soil should be rich, moisture-retentive, well-drained and high in organic matter. Shelter from drying winds in northern areas. MAINTENANCE: Water well during dry periods, especially the first few years after planting. Add a mulch of straw, pine needles, shredded leaves, or shredded bark to retain soil moisture. Zones 5-8.
ACER palmatum - Japanese Maple
PLANTING: In northern zones, choose a location which receives full sun. Farther south, the location should be partially shaded. Bright sun helps produce the deepest colors in red cultivars. Soil should be rich and well-drained, high in organic content with ample moisture. Shelter from drying winter winds is desirable, particularly in the northern portion of its range. MAINTENANCE: Formative pruning is desirable, as is spur pruning for those cultivars with interesting bark coloration (A. ‘Sango Kaku’, for example). Such pruning should be done in late summer or early fall and, at the same time, any dead branches should be cut back to live wood. Water well during periods of drought, especially in the first 2 to 3 years after planting. Zones 5-8.
ACTAEA (Syn. Cimicifiga)
PLANTING: Space plants according to their ultimate width and plant in partial to full shade -the farther south, the more shade is advised. It is essential that the soil be moisture retentive yet well drained and enriched with organic matter. MAINTENANCE: Keep plants watered during periods of drought. We recommend a winter mulch in the northern areas. To increase plants, divide in spring or fall. Zones 4-8.
ACTINIDIA kolomikta - Ornamental Kiwi Vine
PLANTING: These plants are dioecious-ours are male, preferable for the color. Set out plants 4 to 6 feet apart in sun or filtered, light shade-against a southwest facing wall or fence would be ideal. A. koloomikta is not fussy about soil type MAINTENANCE: Plants will need some initial training and support. Prune for aesthetics and to keep in bounds. Zones 3-9.
ACONITUM species and cultivars - Monkshood
PLANTING: Monkshood requires caution as all its parts are toxic. Set plants 12 to 15 inches apart. They like partial shade in areas with hot summers and intense sunlight; otherwise, full sun is best. The crowns should be set 2 inches deep. A rich, moisture-retentive (but well-drained) soil is best; we recommend a mulch as well, to conserve moisture and promote optimum growth. MAINTENANCE: Keep plants well watered, especially during periods of drought. Divide every three years to promote vigor and heavy bloom; otherwise, plants do not like to be moved. Removing spent flowering stems after blooming season will also encourage heavier bloom. Zones 3-8.
AEGOPODIUM podagraria ‘Variegata’ - Silveredge, Bishop’s Weed, Goutweed
PLANTING: Set out plants 15 to 18 inches apart, bearing in mind that each plant will spread up to 36 inches in two years. Don’t worry about soil, sun or moisture; Aegopodium will grow almost anywhere, making it the perfect choice for difficult patches where other plants have failed. MAINTENANCE: In northern areas, we recommend a winter mulch for the first few years, until plants are fully established. Otherwise, no special care is needed. Zones 3-9.
AESCULUS species - Horse Chestnut, Buckeye
PLANTING: Plant in a deeply worked, fertile, moist soil of acid pH. Can be grown in light shade, but perform best in full sun. Because of their fibrous root systems, they are easily transplanted. MAINTENANCE: Water during periods of drought to prevent leaf-scorch. For best form, A. x carnea ‘Briotii’ should be pruned to a single leader - this is best done during the winter when the plant is dormant. Zones Various.
AGAPANTHUS hybrids - Lily-of-the-Nile
PLANTING: Set out plants about 18 inches apart in a sunny location, making certain not to plant the strong, clumpy root too deeply. The soil should be moisture-retentive, but need not be especially fertile. In areas north of zone 7, plant in large containers and bring in over the winter. MAINTENANCE: Keep plants well-watered during the growing season. Agapanthus will bloom best if pot-bound, but will also bloom prolifically when planted outdoors, as long as they are not moved. Occasionally, however, severe overcrowding will lead to reduced flowering. If that happens, divide the plants as necessary; flowers will again bloom profusely after a couple of years. In the North, containers should be brought in to a frost-free environment for the winter before the fall frost begin. Water should be gradually withheld to encourage the plant to go into a dormant state. Low light and cool temperatures should be maintained during the winter. To induce growth the following spring, put agapanthus in good sunlight and increase watering as new growth increases. Begin fertilizing when this growth has reached 6 to 9 inches and continue regularly through the growing season. Zones 6-10.
PLANTING: Plant in a sunny location with fairly dry soil. Shelter from strong winds if possible. .MAINTENANCE: If not planted in a sheltered location some staking may be needed. Zones 6-10.
AJUGA - Bugleweed
PLANTING: Set out plants in the spring, 12 inches apart in part shade/sun. That the soil be well-drained is Ajuga’s most important requirement; if necessary, add compost and coarse sand to heavy soils to lighten and improve drainage. MAINTENANCE: Keep soil moderately moist, watering to a depth of 6 inches during periods of drought. Mulch in winter without covering the tops of the plants: this will prevent damage to the shallow roots from alternate freezes and thaws. Zones 4-10.
AKEBIA quinata - Fiveleaf Akebia, Chocolate Vine
PLANTING: Set out plants 15 to 20 feet apart in a light, well drained soil of average fertility. To train the vine to climb, provide a sturdy support. To use as a ground cover, plant away from cultivated areas as A. quinata produces invasive underground runners and stems that root readily upon touching the soil. MAINTENANCE: Little if any fertilization is required, but water thoroughly during periods of drought. Prune every year, either in fall or early spring-don’t be afraid to prune to the ground to control this vigorous spreader. Zones 4-9.
ALBIZIA julibrissin - Silk Tree, Mimosa
PLANTING: Plant in average, well drained soil that retains some moisture. These plants need full sun. MAINTENANCE: Pruning, to restrict size, may be done in early spring. Water freely from spring to fall and a monthly application of a water soluble fertilizer is beneficial. Zones 6-9.
ALCEA rosea - Hollyhock
PLANTING: Set out plants 2 to 21/2 feet apart in either spring or fall. A moist, well-drained soil and full sun are preferred - if necessary add compost and coarse sand to lighten heavy clay soil. Set crowns slightly below the surface of the soil. MAINTENANCE: Keep well-watered during periods of drought. Hollyhocks may require staking to protect them against strong winds. Hollyhocks may tend to be rather short lived and require replacement every few years. Zones 3-9.
ALOCASIA & XANTHOSOMA - Elephant Ears
PLANTING: Plant 3 feet apart in an average but moisture-retentive, well-drained soil. Performs well in full shade but tolerates up to half a day of morning sun as long as it is watered regularly. MAINTENANCE: Water regularly and mulch to keep the soil evenly moist. In colder areas, move indoors to a bright room in the fall as a houseplant. It can also be cut back and stored as a dormant plant in a cool, dark basement. Check the soil every 4 to 5 weeks to keep it barely damp. In zone 8, add a 3-inch mulch of leaves, pine needles, or straw for extra winter protection. Alocasia zones 8-11; Xanthosoma zones 9-10.
ALSTROEMERIA - Peruvian Lily
PLANTING: Outdoors, in the far south, set bulbs 1 foot apart in a rich but light, well-drained but moisture-retentive soil, and in a location receiving partial shade. In zones 6-8, set out after danger of frost is past, planting 4 to 6 inches deep, and mulch well. Indoors, plant in the autumn, using a suitable potting mixture and water sparingly until growth starts; then water amply throughout blooming season. MAINTENANCE: Water during periods of drought. We recommend a winter mulch in the northern spectrum of its hardiness zones. Farther north, after foliage has matured in fall, dig bulbs and store in damp sand or suitable material, to keep bulbs from drying out. Indoors, after blooming, taper off watering till foliage matures. Keep plant in its pot and fairly dry until ready to begin the growth cycle again; or remove from soil, dry and store in a shallow container of damp sand until planting time. Zones 5 (with protection)-9.
PLANTING: Set standard varieties 20-25 feet apart. Dwarf and semi-dwarf types can be spaced 10 to 15 feet apart in the orchard. Apples perform best in full sun in an acidic, well-drained loamy soil that contains plenty of organic matter. Dig a hole large enough to accommodate spread out roots and set the plant with the topmost roots one to two inches below the soil, firm down the soil and water thoroughly. MAINTENANCE: Water regularly during hot, dry periods. Have a soil test made through the local Extension Service to determine what type of fertilizer may be needed and for recommendations for a spray program to control insects and diseases if needed. For standard trees, thin fruit in midsummer along the branches so they are 6 to 7 inches apart. Harvest the fruit in the fall when it separates easily from the branch with a simple twist; avoid jerking the fruit which can damage the fruit spur and reduce fruit production in future years. Zones 4-8.
AQUILEGIA hybrids - Columbine
PLANTING: Set plants 12 to 15 inches apart. Choose a soil that’s fertile and well-drained, but moisture-retentive. In the cooler regions of the north, full sun is fine — so long as plants receive ample moisture. Farther south, partial shade is preferred. MAINTENANCE: Water well during periods of drought. If foliage becomes unattractive by summer cut it back to ground level; it will regrow in a very short period of time to continue its delicate display until frost. Zones 3-9.
ARACHNIODES - See Ferns
PLANTING: Set out tubers in spring, planting 4 to 6 inches deep in part or full shade, in a humusy, moisture-retentive soil. Space A. triphyllum 12 to 15 inches apart. Space A. tortuosum and A. griffithii 18 to 20 inches apart, and space A. speciosum 2 to 3 feet apart. Arisaema species make excellent pot plants, too. To grow in pots, plant one bulb in a 6-inch pot, planting 4 inches deep in a good, well-drained but moisture-retentive potting soil. MAINTENANCE: Foliage usually goes completely dormant in midsummer, especially in hot, dry conditions. Keep well mulched with well-rotted organic matter to retain soil moisture and organic matter levels. Zones Various.
ARISTOLOCHIA - Dutchman’s Pipe
PLANTING: Set plants in sun or partial shade in average, well drained soil. MAINTENANCE: Keep watered and fertilize established plants in early spring with a handful of 5-10-5 fertilizer scattered around the base of each plant. Water in well. Provide strong supports and early guidance as needed. Thin and cut back as needed to reduce density. Prune spring or summer. Growth rate rapid but slow to start. Zone 4-8.
ARUNCUS - Goat’s Beard
PLANTING: Set out A. dioicus 20 to 24 inches apart; A. aethusfolius 6 inches apart. Choose a moisture-retentive soil that contains plenty of rich humus, and a shady location. MAINTENANCE: Water during periods of drought. Remove spent flower heads - otherwise, little or no maintenance is required. Divide as needed. Zones 4-8.
PLANTING: Set plants 12 to 15 inches apart. Choose a sunny location where the soil, which need not be particularly fertile, is well-drained. Plant the crown 2 to 4 inches deep. MAINTENANCE: Asclepias is late to break dormancy in the spring, so take care not to remove it accidentally during cultivation. Because of its extensive taproot (which helps account for its drought-tolerance), avoid disturbing established plants. Newly set out plants may benefit from a winter mulch; otherwise no special care is needed. Zones 3-9.
ASIMINA triloba - Pawpaw, Indian Banana
PLANTING: Plant in full sun to shade. Best fruit production is in sun. Soil should be slightly acidic and well drained. Be sure to plant at the same height as in the container. Fruit set is best when more than one tree is planted for cross pollination. MAINTENANCE: Fairly drought tolerant, but best if watered during dry periods. If a single tree is desired, remove the occasional sucker. If not removed, they will form colonies. Fruits turn purple or black and get soft when ripe. Eat only ripe fruit as it can cause nausea when eaten unripe. Zones 4-9.
ASTER species - Hardy Aster
PLANTING: Set A. x frikartii 15 to 18 inches apart, others 18 to 24 inches apart in sun. A. frikartii will also grow in light shade and has an exceptionally long blooming period that starts in summer. In general, asters prefer fertile soil, but will tolerate poor soils as well. Soil should also be well-drained, but take care to provide ample moisture, particularly in fall when plants are in bloom. MAINTENANCE: Pinch or even shear back several times during the early part of the growing season to promote vigorous, compact growth. Divide every 3 years or as necessary, replanting the younger, more vigorous pieces from the outside of the clump. To control mildew naturally, avoid overhead watering, and plant away from hedges or fences to assure satisfactory air flow. If you must, a monthly spray with wettable sulfur will ensure mildew control.
ASTILBE - Meadow Sweet
PLANTING: Set out plants in spring or fall, 15 to 18 inches apart. Astilbes prefer partial to full shade, but may be grown in sun in northern areas if particular attention is paid to maintaining a constant supply of moisture, especially early in the growing season. (Failure to do this will produce poor, chlorotic, unattractive foliage.) A soil well-enriched with organic matter is essential. MAINTENANCE: Astilbes are vulnerable to drought, and should be watered liberally; a year-round mulch will help retain moisture and moderate soil temperature. Other than that, and dividing established plants every few years, preferably in the fall, they are relatively care-free. Their plumy inflorescences, even when dry, provide winter interest, so we suggest that they not be cut back until spring, prior to the onset of new growth. Zones various.
ASTRANTIA major - Masterwort
PLANTING: Performs best in light shade and an evenly moist, rich well drained soil. In cool summer areas, it can be grown in full sun as long as the soil remains moist; if grown in a hot region, part shade is imperative. Space 16 inches apart. MAINTENANCE: Remove the spent flowerheads to prevent them from going to seed. Divide as needed by digging plants in fall or early spring. In hotter areas, divide in fall. Zones 4-7.
ATHYRIUM - See Ferns, Hardy
AVOCADO (Persea americana)
PLANTING: Use a loose potting soil that drains well, such as the type recommended for cactus that contains extra sand or perlite. Gradually shift into larger pots as needed. Place the potted plant in a sunny window indoors or move outdoors gradually into stronger sun for the summer. Water about once a week during the summer but only once every 2 to 4 weeks during the fall and winter. Always check the soil before watering to make sure that it is beginning to dry out. If in doubt as to whether to water, wait a day or two and check it again, since it probably doesn’t need water at that time. Water thoroughly making sure that the water flows freely through the drainage holes, however pour out any excess water from the drainage tray so the plant won’t set in water for any length of time. Use a water soluble fertilizer, according to label directions through the summer. Move indoors in the fall before the temperature drops below 50 degrees at night to a sunny, warm window. MAINTENANCE: The flowers can be pollinated by allowing a fan to blow across the plant or by gently shaking the plant each day to scatter the pollen. Pinch or cut the branches as desired to keep the plant bushy and within bounds. Gradually shift into larger pots as needed. Harvest the avocados when they turn from green to black and are still only slightly soft. Clip them from the tree with a short stem attached and handle carefully to avoid bruising. Allow about 14 months for each avocado to ripen fully. Zones 9-12.
PLANTING: Azaleas prefer a soil of high organic content, markedly on the acid side, ideally with a pH range of 4.5 to 6. If necessary, soil sulfur or aluminum sulfate should be added to acidify neutral or alkaline soils. Ample quantities of leaf mold, well-decomposed compost or peat moss, which will help make it acidic, should be incorporated into the soil prior to planting. Set plants out in a shaded or partially shaded location (the more shade the further south you are), in a location protected against drying winds. Soil should be moisture-retentive but well-drained. Spacing is determined by the ultimate size of the plants chosen and by the rapidity with which you wish to achieve landscape effect - in general 3 to 5 feet apart is proper. Of paramount importance is the depth to which Azaleas should be planted - never set the plants with the top of the root ball any deeper than the surrounding soil level! MAINTENANCE: Because they are shallow rooted, Azaleas should not be cultivated. Instead, use a mulch of for example pine needles or leaf mold. This will hold moisture and discourage weeds. In poor soils, or to enhance slow-decaying mulch, add a special azalea fertilizer in spring before new growth appears. Water deeply once a week when there is little or no rainfall. Prune after flowering only as necessary to remove dead or unwanted branches; pinching the tips of new shoots will encourage bushiness. Zones various.