Lilacs in New Hampshire

Lilacs have been apart of New Hampshire ’s landscape for almost three centuries. They were initially introduced into America from England in 1750 and were later incorporated into Govenor Benning Wentworth’s home landscape in Portsmouth New Hampshire . They are among the most versatile shrubs grown and offer many opportunities to a garden design. Today these fragrant beauties continue to bloom in towns, villages and on farms throughout the state.

The common purple lilac, Syringa vulgaris was adopted in March 1919 as New Hampshire ’s official state flower. Although lilacs display flowers that are among the most delicate of the ornamentals, the plants are among the most hardy. All lilacs belong to the genus Syringa, but since their initial introduction, hundreds of new species and hybrids have been developed. Some of these newer varieties can survive winter temperatures of -60ºF. There have been cultivars developed with features that focus on the unusual: leaves, flowers, and blossom fragrance. These varieties offer the gardener the opportunity to break with tradition and try something new.

Lilacs can vary in shape and/or form. Some may be rounded, vase-like, tall and spreading, tall and straight or a combination of these shapes. Their size also varies between species and cultivars and certainly with age. Some tree lilacs are known to grow 25 feet in height, while shorter cultivars may only grow to a height of 5 to 8 feet.

Lilac flowers span a wonderful array of colors (white, violet, blue, lilac, pink, red and purple) and the fragrance varies between cultivar and species. The petal colors may overlap in shades and tones and some are bicolor. Shades vary depending on weather (hot versus cool and dry versus wet), year, soil, environment and overall location differences.

Flowering time is highly dependent on the species, cultivars and spring weather conditions. Most lilacs flower from mid-May to the first of June. However, early, warm conditions will stimulate earlier flowering. Lilacs usually flower for two-weeks and flower buds are occasionally injured by a late spring frost.

When selecting that special traditional lilac what criteria should you follow? According to the Arnold Arboretum the “best of the best lilacs for New England gardens, should be those that are highly fragrant, display many flowers at eye (and nose) level, resist mildew and leafroll necrosis, and produce new growth that does not obscure the flowers and enough suckers to replace old or injured stems”. Ideally the gardener should be able to find this perfect lilac in many different colors, in both single and double form, and varying bloom times.

There are a number of favorite lilac varieties grown here in our Granite State . When selecting them keep in mind how you want to use them, and choose varieties accordingly. Some of the most popular varieties include species like:

• Syringa meyeri, ‘Palibin’ lilac. This is a slow growing, broadly rounded plant with dense foliage. It grows from 4 to 8 feet high and equally as wide or wider. It has purple-violet flowers and begins flowering when quite young.
  
  
• Syringa chinensis, ‘ Chinese’ lilac. This is a cross between the Persian and the common lilac and is somewhat taller than the Persian. It is a graceful, broad spreading shrub. It has arching branches and delicate purple-lilac, fragrant flowers that bloom in mid-May. It grows to a height of 8 to 15 feet and has variable mildew susceptibility.
  
  
• Syringa patula, the Manchurian lilac, is a Korean lilac that has dense foliage, grows from 5 to 8 feet in height and is 4 to 5 feet wide. Its foliage often has an attractive fall color, and its primary flower color is lilac-purple. Its primary cultivar is called 'Miss Kim'.
  
  
• Syringa vulgaris, the common or French hybrid lilac, is the most common and popular species. It is a hardy deciduous shrub with heart-shaped leaves of deep green. Its flowers are extremely fragrant, come in various flower types and in an array of colors from white to purple. Cultivars grow from 8 to 20 feet tall.
  
  
• Syringa reticulata, the Japanese Tree lilac, is often listed as a small tree rather than a large shrub. It grows 25 feet high and 20 feet wide. It bears white flowers in early to mid-June. Unlike most other lilacs, it is resistant to mildew, scales and borers.
  
  
• Syringa Pekinensis, the Chinese tree lilac, is smaller than the Japanese Tree lilac growing to a height of about 15 feet to 20 feet high. The flowers of this species are a yellowish white (creamy) and appear in late May to early June.

Lilacs are usually purchased as containerized or bare root plants and should be 2 to 4 feet tall (big enough to stand transplanting). Lilacs are adaptable plants, but perform best in sites with soils high in organic matter and good water drainage, adequate nutrition and full sun. Poor soil drainage can lead to poor growth and flowering. Their drought and winter hardiness makes them easy to grow and they can survive, even when neglected.

Lilacs that are bought B&B are best planted in early spring before bud break. This will enable the plant to establish a good root system before winter sets in. Lilacs bought in containers should be planted in early spring or fall. When planting a lilac you will want to dig a hole big enough to accommodate the roots without bending or breaking them. The hole should be three times as wide as the root ball and as deep as the height of the ball. Once the hole is dug place the plant in the planting hole with the trunk flare ½ -1 inch above the surrounding grade to allow for some setting.

Spacing the plants is important, larger varieties should be planted at least 12-15 feet apart to provide ample spreading room as they grow. Smaller or dwarf varieties will require less spreading space. Also avoid planting them where there will be competition with trees and other shrubs.

Lilacs require a minimum amount of care once established and seldom will need supplemental watering unless faced with a drought situation. Lilacs do attract a number of insects and diseases, but only a few cause serious injury. Powdery mildew is the most common disease. It appears on foliage in late summer, and gives leaves a whitish, felt-like dusty appearance. This disease does little harm and control measures are not generally recommended.

Oyster-shell scale and San Jose scale are insects that pierce the bark and suck sap from the plant, thus weakening flower-bearing stems. If either of these becomes a major problem you can contact your local UNH Cooperative Extension to get proper controls (1-877-398-4769).

Lilac borers, as the name suggests, are small boring caterpillars which work themselves into the wood of the plant, sometimes leaving small amounts of sawdust as evidence of their presence. This boring activity occasionally causes death to larger branches. Suggested control for this would be to prune out infested branches if possible or dig out the larvae using a knife or a piece of wire. The key is to try to keep the plantings healthy and vigorous by proper cultivation, fertilization, pest control and watering.

Should you have some extra time this spring and enjoy festivals, you may want to consider taking in the annual Lilac Festival at Wentworth Coolidge, “ Lilacs Along the River”, Portsmouth, NH or the Annual Lilac Time Festival generally held Memorial Day weekend in Lisbon, NH . These spectacular events would be a great treat for any lilac enthusiast to attend.

For more information call the UNH Cooperative Extention’s Family, Home & Garden Center’s Info-line (toll free) at 1-877-398-4769. Trained volunteers are available to answer your questions Monday through Friday 9:00am to 2:00 p.m.

By Rachel Maccini, Coordinator, Family, Home & Garden Education Center, UNH Cooperative Extension, Hillsborough County