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For many people, the warm season begins with the lilac blossom, because the lilac bush usually shows its flowers in May. However, there are also varieties that flower earlier or later. Therefore, you can prolong the lilac bloom by cleverly combining the varieties.

Syringa, the botanical name of the lilac, is a genus of plants from the olive tree family (Oleaceae). About 20 to 25 species belong to the genus. There are an estimated 300 lilac varieties in total. Syringa is often confused with summer lilac, botanically Buddleja. While the two genera may look similar due to their panicle-shaped flowers, they are not related.


When a lilac bush blooms depends a little on the variety. As a rule, however, the time of flowering is between May and June. So it is an old and traditional custom to give a beautiful bouquet of lilacs on Mother's Day. If the weather is mild, the plants can start flowering as early as the end of April, and if the weather is bad, the flowering can sometimes be postponed until the end of May. The duration of the lilac bloom is between four and eight weeks, depending on the variety.

Varieties and flowering times

When does lilac bloom?

Below are the flowering times of the most popular lilac species:

Common lilac (S. vulgaris)

The classic and its varieties bloom in May.

Hyacinth lilac (S. hyacinthiflora)

The hyacinth lilac usually flowers before S. vulgaris, i.e. already in April. In mild weather and in regions with a mild climate, however, it can start flowering as early as late March or early April.

Chinese lilac (S. chinensis)

The lilac variety unfolds its blooms only in May. It has arching, overhanging panicles of flowers.

Canadian lilac (S. x perstoniae)

This lilac variety does not flower until mid-May at the earliest. The hybrid is considered to be particularly hardy and is therefore very well suited for colder regions.

Korean Dwarf Lilac Miss Kim (S. patula Miss Kim)

The flowering period of "Miss Kim" is from May to June. As a dwarf lilac, it only grows up to two meters high.

Hungarian lilac (S. josikaea)

This lilac variety blooms at about the same time as the classic lilac varieties, i.e. in the merry month of May.

Pearl lilac (S. swegif.webplexa)

The flowering time for the pearl lilac starts a little later, namely in June. Its flowering period extends into July.

Meyer's Lilac 'Palibin' (S. meyeri Palibin)

This special variety belongs to the dwarf lilacs and unfolds its blooms in June.

Bow lilac (S. reflexa or S. komarowii)

The arched lilac, also known as Komarov's lilac, is in full bloom in June.

Royal lilac (S. chinensis)

The royal lilac starts flowering a little later than the common lilac. Flowering begins in May only when the weather is particularly warm. As a rule, the royal lilac flowers from June to July.

Tree Lavender (S. reticulata)

The Japanese tree lilac flowers from June to July. Its flowers smell of privet.

Autumn lilac (S. microphylla)

The main bloom of the autumn lilac is between May and July. However, unlike many other varieties of lilac, its flowering lasts until October.

Lilac bush does not bloom

If the lilac bush does not unfold its flowers, this can have various reasons. Usually the causes are:

  • too dark location
  • unsuitable soil
  • too little or too much fertilizer
  • pruning too hard or wrong
  • late frost

The solution to the problem or action depends on the cause, of course, unless late frosts have frostbitten the buds. If the location is too dark and the plants like it very sunny, then the only thing that helps is to transplant the shrubs. This is also the case when the soil is unsuitable for the shrubs. If the soil is too lean, for example, a handful of horn shavings will help.

tip: Use horn shavings sparingly, because this fertilizer contains a lot of nitrogen, which actually prevents flowering but promotes foliage. The latter, in turn, is very important for flower formation.

If the two causes location and soil can be ruled out, then you should spoil the plants with a generous dose of mature compost before they sprout. If you cut back the shrub before flowering, then you probably cut off the buds that had already formed. Since the lilac bush buds in autumn, you should only cut it shortly after flowering. And here, too, we recommend: less and more often is more!

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