Caring for summer lilac — tips and things worth knowing about Buddleja davidii

Botanical name: Buddleja davidii, Buddleja davidii hybrids
Other names: summer lilac, butterfly bush, butterfly lilac
Use: summer flowering wood, ornamental wood, nectar plant for insects
Origin: China and Tibet
Flower colours: violet, blue, pink, red, white
Flowering period: July-September
Special features : Wood with a luxuriant abundance of flowers that magically attracts butterflies and other insects. Convinces with harmonious growth without much care. The ‘Buzz®’ group was created through breeding and selection. This dwarf form is available in different colors and grows to a maximum height of 1.50 m.

Butterfly bushes are well-known and popular shrubs that enrich the garden with a rich abundance of flowers. With their long flowering period and uncomplicated nature, Buddleja delight in every location. Nectar and the scent of the flower spikes magically attract butterflies, hence the name butterfly bush. The growth is harmonious and with a height of 2 to 3 m the wood sets special accents in a single position. The hardy plant also finds its place in mixed hedges and natural gardens. Many of the 100 species known worldwide, such as the Royal Red summer lilac, come from areas with poor soil and high levels of sunshine, which also explains the site conditions for the summer lilac.

In which location does the butterfly bush feel most comfortable?

Buddleja davidii grows easily in any garden soil. The tree does well even on light sandy soils. Here the soil can be improved with high-quality potting soil when planting, giving the wood optimal starting conditions. Soils that tend to waterlogging are not ideal. With a drainage layer introduced during planting, unwanted moisture can be minimized. Sunny locations are ideal, the butterfly bush does not feel so comfortable in the shade and there are fewer flowers.

How do I plant my summer lilac in the garden?

Planting time for Buddleja is from February to September. This gives the plants enough time to root and they are well prepared for the first winter. Planting in spring is recommended in climatically unfavorable locations.
Plant your Buddleia as follows:

  • Dig a planting hole twice the size and depth of the plant’s root ball.
  • For soil that tends to compact, place a thin drainage layer of gravel or sand in the planting hole.
  • Water the Buddleja thoroughly before planting.
  • Place the root ball in the planting hole and fill it up with high-quality potting soil.

Water the new planting with 20 liters of water.

How do I water Buddleja davidii correctly?

Buddleia is quite undemanding after planting and continues to grow well. Needs-based watering is important in the first year after planting. This means that additional watering is required during phases without precipitation. Depending on the temperature, soil conditions and size of the plant, the amount of water and the frequency of watering will vary. Basically, larger amounts of water given at intervals help better than daily small doses. In the first year after planting, watering of 10 to 20 liters every 2 weeks may be necessary. However, always water according to rainfall and temperature. If the wood is firmly rooted, aadditional watering only necessary on extremely light soils and in phases without any precipitation. Basically, the care of summer lilac is very easy and the wood is also ideal for beginners.

How do I fertilize my summer lilac?

Buddleia has low demands on nutrients. It is therefore sufficient if the wood is supplied with compost or organic garden fertilizer when it sprouts in spring. With the purely vegetable natural fertilizer you give the ornamental shrub a slow-acting nutrient supply for the next few weeks. Mineral fertilizers are only necessary on sandy soils, since the humus content is lower here and it is therefore more difficult for the plant to be supplied with nutrients.

How do I prune my summer lilac?

A cut is not absolutely necessary with the Buddleja davidii, but can be carried out if the plant needs rejuvenation. This rejuvenation helps older plants to sprout bushy again. By nature, the wood is bare at the bottom of the trunk. With a radical pruning, the summer lilac grows back in multiple shoots. The optimal time for a rejuvenation cut is early spring. Danger! Pruning too late can prevent flowering. Lilacs bloom on one-year-old wood. If you just want to curb growth and take back oversized plants, this can be done in autumn. This pruning serves to limit the heightand the design of the form.

Cut back after flowering:

By cutting off the flowers, you can encourage reblooming. Cut off the panicles directly on the stem and, depending on the weather, some smaller flowers can be enjoyed on the bush in late summer.

How do I overwinter my summer lilac?

Freshly planted Buddleja davidii need good winter protection for the first 2 to 3 years. Older plants are well hardy in the wine-growing climate, but winter protection is always advisable in cold areas. The protection of fleece, leaves and twigs helps against freezing back too much. Older plants cope better with low temperatures. If they freeze back, the robust trees will sprout out of the wood again.

How do you manage summer lilac care in the pot?

With the new varieties of the ‘Buzz®’ series, summer lilacs can also be planted in large pots and tubs. So it is possible to enjoy the butterfly magnet Buddleja on the balcony or terrace. The dwarf summer lilac convinces with colour-intensive, fragrant flowers and compact, overhanging growth. With their dense branching, these dwarf forms can be kept in pots for many years. Due to their vigorous growth, the usual Davidii hybrids are only suitable for pots for a few years.

Then the garden plants should be transplanted into the ground where the buddleia care is very easy. Choose a vessel with a diameter of at least 70-80 cm and a height of 60-70 cm. When planting, it is important to ensure that a drainage layer is placed on the bottom of the container and that high-quality potting soil or potting soil is used. As with all trees and shrubs in the tub, an even water supply is essential for success. Long periods of drought or waterlogging are not conducive to plant development.

Our gardening tip: If possible, you should overwinter the Buddleja in a pot in a frost-free place with temperatures below 10 °C. This ensures that the shallow-rooted plants get through the winter well. There is also the option of protecting the pot with special fleece.

The compact growing dwarf form of the butterfly bush impresses with tireless flowering. This buddleia in white and other attractive colors blooms non-stop from mid-June to autumn. By removing the faded inflorescences, the abundance of flowers is promoted and seed formation is prevented. The dwarf form can also be planted out in the garden.

What pests and diseases can the butterfly bush get?

Buddleia are robust and are very rarely attacked by diseases and pests in the optimal location and with good care.

With the right site conditions, buddleia care is easy and the plant healthy. Plants that suffer from water stress or are in too shady locations are more susceptible to pests. Here is a possible problem that can occur with buddleia:

spider mites

The affected leaves have silvery dots on the upper side and webs are visible on the underside of the leaves. Spider mites appear on summer lilacs especially in warm, dry weather. It is usually sufficient to spray the plants with water and treat them with plant strengtheners. These organic active agents contain natural plant extracts that contribute to the vitalization of the plant.

Frequently asked questions about Buddleia

In locations that are too shady, the summer lilac flowers only sparsely or not at all. Late frosts and cutting back too late can also be responsible for the lack of flowering.

What colors do butterfly bushes come in?

There are summer lilacs in white, violet, blue, pink and red.

What can be the reason for yellow leaves?

Yellow leaves (sometimes with brown spots) are often the result of waterlogging. Check the conditions.

Does cutting back in spring damage flowering?

The flowers of the summer lilac are formed on the new shoots. Therefore, pruning in spring is optimal for forming the plant and regulating growth.

Do faded flowers have to be cut off immediately?

In order to prevent undesirable seed formation, it is advisable to cut off the flower panicles immediately after flowering. But it is not absolutely necessary.

Can the summer lilac be planted in a pot?

Only the group of dwarf Buddlejas in pots is recommended as a container plant. The common species grows too much and is only suitable as a container plant for a short period of one or two summers.

What care is needed for buddleia after a frost?

Buddleia are particularly damaged by late frosts in spring. A slight pruning helps to remove the broken shoots and stimulate the plant to sprout again

Bee-friendly shrubs, butterfly bushes, hibiscus and much more It is important that the insects find suitable flowers even in summer. With the right shrubs, you can offer beneficial insects valuable food for many weeks.


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