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Lilacs in the Alaskan Landscape
Lilacs can be a wonderful addition to the Alaskan landscape. With a genus of about 20 species of deciduous shrubs and small trees found in woodland and scrub from S.E. Europe to E. Asia, there are nearly 40 different types available in local Alaskan nurseries. They have nice form, and offer up a very delightful, spring fragrance from the pyramidal or conical panicles of small, tubular flowers. The flowers make lovely aromatic bouquets for the spring gardener.
Growing lilacs takes a tolerant and optimistic gardener, as it may take up to 4-7 years for a newly planted shrub to bloom. However, they can live a long time and grow up to 20 feet in height. The common or old fashioned lilac is the most fragrant variety and is available in shades of purple, lavender, pink and white. They are prone to powdery mildew, and are often victims of moose attacks.
Canadian hybrids (combinations of Syringa x prestoniae, Syringa hyacinthiflora, Syringa villosa and Syringa josiflexa) were developed for their hardiness and large flower clusters. They have a little less fragrance and bloom slightly later than the common lilacs. Canadian hybrids are hardy, most shun powdery mildew, and come into flower in the same length of time as any transplanted shrub. James MacFarland may bloom sooner, often in the first year. They are distinguished by dark green, elongated leaves, while the common lilac is recognized by its dull green, heart shaped leaf. The flowers of Canadian hybrids are mostly in the pinks and pale lavenders, but new varieties include intense purples and white.
Small shrub lilacs for South-central Alaska include dwarf Korean lilacs, Syringa meyeri, and Syringa patula 'Miss Kim'. These lilacs do not require pruning, and produce small, rounded clusters of pale lavender flowers in mid-summer. The flowers are intensely fragrant. Thin branches and small, glossy, dark green leaves give a fine overall texture making these shrubs excellent for a small landscape.
The warmest parts of Anchorage may have success with the Japanese tree lilac, Syringa reticulata and the Persian lilac, Syringa persica. The Japanese tree lilac is usually grown as a single-trunked small tree maturing to 20 ft. Its elegant, dark brown-bronze bark is an attribute year round, and the creamy white flowers are a bonus in mid-summer. It grows no more than 10 ft. high and has bluish-green leaves and early, pale purple flowers.
Lilacs require a well-drained, sunny planting site. They won't be happy in a bog. Raised beds or mounds are good ways to get their roots above damp ground. Watch the planting height when placing lilacs in the ground. Look for a natural flare at the base of the trunks indicating the proper planting height. Lilacs, like most other landscape plants, don't like to be buried too deep. Lilacs need sunlight. Sunshine is necessary to produce the energy needed for flower production. The dwarf shrub types are an exception and will flower in partial shade. Aside from sunlight and drainage, lilacs are tolerant shrubs. References vary on the soil pH preference, some say lilacs are widely adaptable, others suggest a strict range of pH 6.5 to 7.5.
Pruning is a lifetime activity for lilacs. Plants should be rejuvenated each year by selectively removing the oldest trunks at ground level. Rejuvenation pruning is useful for shrubs because it keeps them in a youthful, vigorous growing condition. Removing the oldest stems and thinning the youngest sprouts allows sunlight and air circulation to reach the center of the plant discouraging diseases. Spent flower clusters should be pruned off before the plant puts effort into seed formation. Lilacs produce flower buds in the fall for the following spring's show. With this in mind, pruning done right after flowering removes the least potential flowers. Lilacs will bloom the next year even if they are not pruned, but the old bloom left on from year to year is unsightly. Another way to increase air flow around lilacs is to prune them like a small tree - pruning branches and leaves up to about 1/3 the height of the shrub.
Powdery mildew is a superficial disease that plagues common lilacs by the end of summer. The white powdery fungus does not harm the plant, but it is an unsightly nuisance. Sunshine and good air circulation will keep powdery mildew at a minimum. Fungicides are effective if applied as a preventative before you see the white powdery evidence on the leaves.
There are very few ways to protect lilacs from the ravages of hungry moose. A few suggestions include a 6 foot fence to keep moose out of the yard, a wire cage around the lilac, or an abundance of scrub brush available as moose fodder. One Anchorage lilac grower states that S. villosa and James Macfarlane are a little less prone to moose munching than the common lilac.
Approximately 1 cup per mature plant of 8-32-16 pellet fertilizer shortly after leaf out in early May and again at the end of July and a little lime at either of the two fertilizations.
Photo courtesy of Mel Monsen, MG