Author: Webmaster

from The Frelinghuysen Arboretum

Culture

Lilacs grow best in full sun and well-drained soil. They prefer neutral soil with a pH range of 6-7. Many soils in the northern New Jersey area tend to be on the acidic side so lilacs may benefit from a handful of ground of limestone applied every other year. Lilacs also benefit from a spring application of fertilizer. Use an all-purpose, granular fertilizer such as 5-10-5 or 10-10-10 and follow the directions on the package. Do not use a high nitrogen (lawn) type fertilizer as it inhibits flower bud formation. Water your plant well after fertilizing. Lilacs resent competition from other plants, so keep the base well weeded and cut back other plants that may be crowding out your lilac. Two to three inches of mulch at the base of the plant will keep down weeds and hold in moisture. While lilacs are a tough and long-lived plant, they appreciate regular watering during a dry spell or drought.

Planting

Select a sunny site with well-drained soil in an open area. Lilacs need good air circulation. Dig a hole 3X the width of the pot or ball of the plant. If you have a very small plant, be sure the hole is at least 18″ across. Amend the soil with well rotted compost, a cup of lime and some fertilizer. Firm the amended soil to remove excessive air pockets. Place the top of the lilac ball slightly higher than the surrounding ground and firm more soil over and around the roots. Water well. Mulch applied to the base of the transplant helps keep the soil moist. Water your lilac twice a week for the first month, unless there are regular rains. Keep lilac well watered throughout first growing season.

Pruning

Pruning is best done in late March or early April, before the leaves have emerged. Healthy lilacs only need occasional pruning to remove dead or spindly branches. Older, taller plants will benefit by pruning out, at the base, up to one-quarter of the largest branches. Pruning forces new growth to emerge at the base and opens up the plant to more air circulation and light. It also keeps the flowers at eye level. Very old and overgrown lilacs sometimes need total rejuvenation. This may be accomplished by removing one-quarter of the oldest branches each year for four years. If your lilac produces too many suckers at the base, prune or dig out the excess. Suckers with good root systems may be potted up and given to friends or planted in another location in your garden.

Diseases and Pests

Lilacs in our area suffer from three types of problems. The most common disease is powdery mildew that coats leaves in late summer and fall with a silvery-white film. This disease rarely harms a healthy plant, but may look unsightly. The Common Lilac (Syringa vulgaris) and its cultivars are most susceptible to this disease. This problem may be treated with a fungicide or wettable sulfur. For best result follow the instructions on the product. Another common problem is lilac borer. This small, white larva bores into the heartwood of the lilac eventually weakening or killing the cane. It leaves a small pile of sawdust coming out of the entry hole. The best prevention is to prune out the largest, oldest growth and encourage vigorous new growth. The borer does not seem to attack young growth. Borers may be killed with a long wire put into the hole. The third problem lilacs encounter is oyster-shell scale. This tiny pest can rapidly cover lilac canes, weakening and even killing the cane or the entire plant. The pest is light brown or gray and may blend with the bark from a distance. Badly infested branches should be removed and destroyed. Spray with dormant oil in early spring before bud break or with summer oil or Malathion after the leaves emerge. Follow directions.

While the delicate beauty and splendid colors of Japanese Maples have delighted Western gardeners for almost two centuries, they have been revered in the East for over thirteen centuries. Native to Japan, China and Korea these trees do best in light shade and do not like to be dried out. Plant them in soil that has a fairly high content of organic matter and is moist, but well drained. Older, established plants can take some drought. Full sun and winds may burn the leaves, especially the variegated varieties. Most Japanese maples are hardy to Zone 5.

• Acer palmatum var. atropurpureum (aka Atropurpureum) – Reddish purple 5-7 lobed leaves, especially in spring, which fades in the summer heat but shows excellent spring and fall color. Seedlings produced from a good selection will show all varieties of coloration. May grow 30-40 in height.
• Acer palmatum Butterfly – One of the older, but still popular, garden tested variegated forms with emerging leaves green with pink margins, maturing to gray green with cream-colored variegation. Fall color is rose-red to purple-red. Habit is upright, vase shaped 12-15 high by 6-8 wide, relatively slow growing.
• Acer palmatum Fireglow – This plant keeps a good red color all season long. The fall color is particularly showy. It has a very upright growth habit and has bronzy red stems.
• Acer palmatum Glowing Embers – This is a Michael Dirr selection, exceedingly vigorous with small dark green leaves that turn orange-red-purple in fall. Its a fast growing, heat tolerant plant, often growing to 30.

• Acer palmatum Karasugawa – The most outstanding feature of this cultivar is its bright pink new growth. Some leaves are almost entirely white with pink edges while others are mostly pink with tiny flecks of white or bright green. As the season matures, the leaves get greener but still retain some pinks and whites. This is not a vigorous grower and it is somewhat tender. The plant rarely grows higher than 6-9.
• Acer palmatum Katsura – This is a dwarf form with leaves that emerge a soft yellow orange with deeper orange margins. As the season progresses the leaves turn a rich green and then bright yellow or orange in fall. It grows to about 5 feet tall at maturity. This variety makes a good bonsai.
• Acer palmatum Okushimo – An upright vase shaped tree that may grow to 24 or more at maturity. Its leaves are an unusual shape, deeply lobed and almost tube shaped. The fall color is an intense gold.
• Acer palmatum Oregon Sunset – This plant exhibits a good rounded habit and has leaves that emerge very red in spring. As the season progresses, the leaves fade to a bronzy red then turn a fiery red in fall.
• Acer palmatum Oshi Beni – The new growth emerges a vibrant orange-red to red, but loses this color in late spring, becoming bronze to greenish red. Fall color is rich scarlet. The plant will grow 15-20 and develops a spreading habit.
• Acer palmatum Red Pygmy – This is one of the cultivars of linearilobum group, with red or bright maroon leaves that are 7 lobed with long strap-like divisions. This tree grows about to 6 by 6. This is an excellent cultivar for a very small garden. The new growth is not always typical, so do not prune out unusual growth as it reverts to normal during its second season.
• Acer palmatum Sango Kaku – A common cultivar praised for the brilliant coral fall and winter color of the young stems. The color is very striking, but is lost as the bark matures. New leaves are tinged reddish but turn a light green for the summer. Fall color is gold with some reddish tints. The tree will grow 20-25 high by 18-22 feet wide. It is not as heat tolerant as some other cultivars.
• Acer palmatum Trompenburg – The leaves are deeply cut creating a lacy look. The foliage is deep purple and persists into summer then it changes to a reddish green. Fall color is red to crimson. The plant grows 13-16 high by 10-13 wide.
• Acer palmatum Versicolor – This is one of the most popular cultivars that will grow up to 25 on 25 to 40 years. Leaves are deep green in color with a varied pattern of markings of colors of white and occasionally pink.
• Acer palmatum var. dissectum – Cut-leaf Maple. The most refined of all maples with leaves of 7, 9 or 11 lobes cut to the point of attachment of each lobe and each lobe is finely toothed. Seedlings exhibit a variety of variation. Plant may only grow 10-12 tall by 20 wide. Old specimens have a remarkable branching structure that cascades.
• Acer palmatum var. dissectum Red Feather – A dwarf plant with extremely lacy, small, fine leaves. The leaves emerge in spring with a reddish color that fades during the summer. Fall color is a beautiful crimson red.
• Acer palmatum var. dissectum atropurpureum “Inaba Shidare – (leaves of rice plant) On outstanding dissectum form with lobes up to 10 cm long. The leaves emerge a deep purple red and retain this color all season. Fall color is a brilliant purple red or crimson red.
• Acer palmatum var. dissectum Seiryu – The only upright form of the dissectum group. The foliage is bright green, which turns strong gold in the fall with reddish tints. Plants may grow up to 20 feet in height.
• Acer palmatum var. dissectum Viridis – This is a catch all term for all green leaf dissected types. Fall color is yellow gold to red. The plant may grow as large and wide as the straight species.
• Acer palmatum var. dissectum Waterfall – This beautiful selection with extremely cascading branches is considered the best of the green leaf dissected forms. The foliage is a rich green all summer long and turns gold with reddish undertones in fall. This cultivar was discovered as a chance seedling at Willowwood Arboretum. The original plant is by the pond near the house.