Lilac trees (Syringa spp.) have been cherished by gardeners across the country for generations, and it’s easy to see why. These deciduous trees or shrubs are easy to care for and have elegant flowers with a wonderfully strong scent that fills the air with a sweet perfume, especially in warmer climates.
The most well-known or common lilac is the Syringa vulgaris. Its flowering season varies from early spring to summer, depending on the variety and climate zone. During this time, these lilac trees burst into masses of white, pink, or purple flowers, creating a mesmerizing display. These plants can be grown as a bush or shrub or trained as a standard. While the botanical name is Syringa, a delightful array of cultivars are available, each offering distinct flower colours and growth rates.
While classic Lilac flowers are typically a pale blue, there are also varieties with deeper purple to mauve and red flowers.
Lilac trees reach full bloom in spring. They might not be as showy the rest of the year, but their spring blooms more than make up for it. They are suited to be grown in garden borders and can be used as a seasonal feature plant.
Dwarf cultivars suited to growing in containers are also available for sale from selected nurseries. The growth rate will vary from 30 to 60cm a year, depending on climate, soil and variety.
Lilacs prefer humus-rich, moist but well-drained soil. They thrive in full sun and, once established, are relatively maintenance-free. A position in full sun is best as not only does it improve flowering, it intensifies the fragrance.
Good drainage is essential. These are a plant that will suffer in wet, boggy soils.
While they appreciate good soil, over-fertilising can result in lush foliage growth but poor flowering. Good mulch and a little well-rotted cow manure each year is usually adequate.
Planting Step By Step
- Choose a position with good sun. 6 hours a day is a minimum for good flowering.
- Make sure the soil is well drained. Hill up the soil in wet or heavy clay soils if needed.
- Dig the soil over well, remove weeds and add some well-rotted compost and cow manure.
- Dig the planting hole twice as wide as the container. Always plant at the same level the plant was in the container.
- Plant in late summer. This gives the Lilac time to put on some root growth before winter.
- Water in with a liquid seaweed fertiliser.
- Mulch around the plant to maintain a cool root run.
- Avoid using too much fertiliser, especially high nitrogen types, as this will promote leaf growth rather than flowers.
Mulch around the plants, well and water deeply during very dry spells.
Removing the older stems not only rejuvenates the bush but it also helps prevent insect pests and diseases.
Lilacs flower on two-year-old wood, so to prune them accordingly. Pruning can be done after flowering. For shape maintenance, a light pruning is sufficient.
Older plants can become a little large and woody over time. For best flowering performance, they may need some severe pruning. If they have been neglected, start by removing all dead and damaged wood, then remove one-third of the remaining stems, starting with the oldest. Over 3-4 years, you will have a healthy, rejuvenated plant.
French lilacs (Syringa vulgaris) can handle heavy pruning. Each year, prune away one-third of the oldest stems around June in Australia. Leave 8-12 main canes and trim them back about 30cm less than your desired height just after flowering for a second flush of flowers.
The Tree lilacs are pruned back to one main stem. Generally speaking, all varieties are best pruned back to a height that will give flowers at head height. This maximises both the visibility and the perfume.
Lilac varieties include: Syringa vulgaris, S. x hyacinthiflora, S. x prestoniae, S. reticulata, S. pekinensis, S. x chinensis, S. pinnatifolia, S. x ‘Albida’, French, Russian, and Fragrant lilac.
Lilac Plants are available for sale from the following nurseries
P O Box 398 Creswick Vic 3363
Retail & Mail Order Specialist Growers of Heritage Roses, Unusual Perennials, Tree & Herbaceous Peonies. Mail order and Nursery Sales.
Carey Gully, Adelaide Hills.
Family business selling a large range of deciduous trees in pots 1-4m high. Crepe myrtle specialist. Includes Ornamental pears & plums, Red maples, Japanese maples, Gingko, Cercis, Ash, Birch, Crab apples, Weeping cherries, Gleditsia, Liquidambar and more. Hedging plants, evergreen trees & fruit trees.
357 Monbulk Road SILVAN VIC 3795
Guaranteed "garden worthy" bulbs, plants and perennials. Visit the website to browse our large range of daffodils or request the latest free catalogue.