Lottah Nursery Tasmania, Australia

CULTURE & CARE OF LILAC BUSHES

Lilacs are low maintenance bushes that will generally take care of themselves when established. The first two or three years are crucial for survival and this is when most losses occur.

PREPARATION. Prior to receiving the lilacs the planting location needs to be cleared of weeds and, if necessary, lime/dolomite applied to the surface at the rate of no more than 250 g/m² to bring pH close to 6.5.

FIRST STEPS. When you receive the bushes they would have been out of the potting media for several days. Rest assured that they have not been allowed to dry out during this period - the roots have been soaked prior to packing and are not likely to dry out for several weeks while plants are in the dormant stage.
Soak the roots in water for 15 minutes and plant right away or hold in damp soil in the coolest part of the garden until they are ready to be planted.
Plant well before onset of warm weather so roots establish in the soil before leaf-break.
Planting holes should not be dug in clay soils as these act as 'sumps' in retaining water. If the base is impervious a far better solution is to build up the soil using retaining walls so that free drainage is not impeded.

SITUATION. For best performance lilacs require exposure to full sun, although they do perform reasonably well in partial shade. The darker lilacs are reported to require partial shade to prevent bleaching of color when exposed to full sun.

WEEDS. Weeds compete directly with lilacs for nourishment and moisture. Keeping the immediate surrounds free of weeds, preferably with some form of a mulch, will do wonders for your lilacs and reduce labor required for manual weeding. Exercise care if applying systemic herbicide because there may be lilac suckers emerging through the weeds.

SPACING. Dwarfs excepted, even with judicious pruning most lilacs grow into large shrubs and require an ideal 3m x 3m spacing. If you absolutely cannot do without several lilacs in a small area stick to the dwarfs - we shall be introducing several, including vulgaris cultivars, in due course.

IRRIGATION. Ensure that the root system does not dry out in warm weather. We use drip irrigation at the nursery and recommend it as being ideal for shrubs. Less frequent thorough soaking is preferable to superficial surface wetting.
On the other hand lilacs are not partial to wet feet so plants need to have adequate drainage.

FUNGICIDES. Lilacs are mainly free from diseases but the S. vulgaris and hyacinthiflora cultivars are susceptible in varying degrees to bacterial blight (Psuedomonas syringa). The disease causing organism is found in most soils and is largely unavoidable. Preventative measures are to reduce nitrogenous fertilizers in the early years and to apply Bordeaux sprays during Winter and early Spring. Overcrowding aggravates the problem since plants dry out slowly. (Plants are given two Bordeaux sprays before being dispatched from the Nursery).

PESTS. The only pest we have have encountered locally is the stem borer. By the time the symptom is recognized (yellowing leaves on a section of the plant or an obvious band of sawdust around the stem in Winter, see image at right) it is too late to save the affected part. Simply prune away the damaged stem, and the plant will recover.
While our collections of roses and ornamental malus have been devastated by local wildlife, lilacs have so far been immune to such damage.

LABELING. Several years from now you may have a most desirable lilac which you might wish to recommend to a friend. Without the proper name, obtaining an identical plant would be near impossible. So please identify your choice plants with permanent tags and keep a written record someplace.

External Link: Another Lilac FAQ