Buddleia: planting and caring for

Buddleia: planting and caring for

Origin and Distribution

There are around 100 different species of Buddleia (bot. Buddleja), which belong to the fig family (Scrophlariacae). These are subshrubs or shrubs that can be summer or winter green. There are also some evergreen species. The genus is primarily native to the tropical to subtropical regions of North and South America as well as Africa and Asia, where most species thrive in sunny, dry and hot locations. Despite the similarity and the name, the summer lilac is not related to the common lilac (bot. Syringa vulgaris), because from a scientific point of view, this belongs to the olive family (Oleaceae).

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  • Buddleia requires the greatest possible planting distance
  • The most beautiful summer lilacs for the balcony - planting and care
  • Buddleia - location, plants, propagation


The quite undemanding Buddleia fits wonderfully both as a solitary plant and in a group planting in full sun garden locations with barren, gravelly soils. The shrub cuts a fine figure both in colorful summer flower beds and perennial beds as well as for greening dry slopes. In front gardens and along garden paths, the plant is also very suitable as a border and can easily be used for planting hedges. Buddleia is also popular in Mediterranean gardens, for example in combination with other Mediterranean plants such as lavender, thyme, sage, etc. Together with other perennials popular with butterflies such as asters or sedum plant, they create an oasis for the little butterflies that is flown a lot .

The species Buddleja davidii, of which there are numerous, colorful varieties, is particularly popular for the garden. The alternate or narrow-leaved buddleia (Buddleja alternifolia) is also very suitable for gardening, whereas the rare yellow buddleia (Buddleja x weyeriana) should only be planted in climatically mild regions due to the lack of frost resistance. However, all species are also ideally suited for keeping in a bucket.

Appearance and stature

The species Buddleja davidii is particularly suitable for the Central European climatic zone with its sometimes harsh and cold winters, of which there are numerous variants with different growth forms, heights and also flower colors. The shrubs grow either wide, upright or compact - depending on the variety - and develop a funnel-shaped, loosely structured crown with strong main shoots. The flowers sit on the loose side branches, which often bend slightly under this weight. On average, these summer lilac varieties grow up to two meters high, although there are also tall varieties with a growth height of up to four meters. Buddleja davidii is one of the evergreen species, because the gray-green leaves often remain on the shoots until frost and only die with the first frost.In winter, the above-ground parts of the plant can freeze back, but the fast-growing shrub sprouts again in spring and quickly reaches its old height.

Blossoms and flowering period

In contrast to the common lilac, the summer lilac does not bloom in spring, but only from July. Its elongated, large and strongly fragrant flower panicles are usually located at the ends of the side and main shoots and are so heavy that the branches overhang. Many varieties bloom well into autumn and delight the viewer with a lush splendor in white, pink, red and purple in different tones. After pollination - and insofar as the withered shoots are not cut away - capsule fruits develop that contain a large number of tiny, winged seeds.


What butterflies taste so good is unfortunately poisonous for humans and pets. The popular species Buddleja davidii in particular contains poisonous saponins and glycosides such as Catapol and Aucubin in all parts of the plant, but mainly in the leaves and seeds. If children or pets try the shrub, symptoms of poisoning such as headaches and nausea, but also cramps, vomiting and diarrhea can occur. Those affected should drink plenty of water and consult a doctor or veterinarian immediately.

The clippings that arise in large quantities in spring are not suitable for feeding to large or small animals such as horses, cattle or guinea pigs, rabbits or turtles. However, you can safely add healthy plant parts to the compost.

Which location is suitable?

As in its natural locations, the Buddleia feels most comfortable in a sunny and warm location. If necessary, a spot in the light partial shade is also possible, provided the plant gets at least a few hours of sun there in the morning and evening. The location, on the other hand, should not be shady: the Buddleia will not feel comfortable here, will stop growing and will not develop any flowers.

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Substrate / soil

Plant the buddleia in loose, well-drained and only moderately nutrient-rich soil, which can also be gravelly and lean. In the course of planting, improve the soil with ripe compost to make it easier for the shrub to grow in its new place. On the other hand, buddleia does not like heavy, loamy soils that tend to waterlogging. If necessary, look for a different, more suitable location for the plant or improve the soil considerably with compost and gravel or coarse sand. In this case, drainage is also advisable so that waterlogging does not arise in the first place.

Pot culture

In particular, the frost-sensitive variants such as the ball buddleia (Buddleja globosa) and the yellow buddleia (Buddleja x weyeriana) should not be planted in the garden bed outside of mild winter regions, but rather cultivated in a sufficiently large container. Other species - Buddleja davidii, for example - are also very suitable for keeping in pots, provided there is enough space.

Special, small varieties are particularly suitable for this. Variants such as 'Purple Emperor' or 'Summer Lounge' are only about one and a half meters high and therefore do not need that much space for themselves - this fact is not entirely unimportant on a cramped balcony. Choose a planter that is as large and deep as possible made of a natural material such as clay or ceramic so that the roots have enough space and do not heat up in the summer heat. Clay buckets, in particular, ensure an exchange of air and thus keep the roots of the plant cool.

Use commercially available potting soil as a substrate, which you mix with gravel and expanded clay (€ 17.50 at Amazon *). This increases the permeability of the substrate, although you must of course not forget the basic drainage in the pot. The bottom of the pot always needs a drainage hole through which excess irrigation water flows into the planter or saucer. Water the plant regularly so that it neither dries out nor constantly stands in wet substrate. In addition, regular fertilization is very important when kept in a bucket, as the plant cannot take care of itself. You should therefore provide them with a liquid fertilizer for potted plants every two weeks, but only in the growing season between April and August. Outside of this time it is only watered, but no longer fertilized.

Preferably overwinter the buddleia in a cool and light place, but frost-free in an unheated interior.

Planting buddleia properly

Since buddleia is mostly grown and sold in containers, you should definitely plant the shrub as deep or high in the garden as it was in the planter. If necessary, mark the spot with a pen. Otherwise, proceed exactly as you would with any other plant when planting the buddleia:

  • Dig a planting hole that is twice as wide and deep as the root ball.
  • In the meantime, submerge the root ball in a bucket of water.
  • There it can soak itself up with water, which in turn helps it to grow.
  • If necessary, improve the garden soil with sand / gravel.
  • If necessary, apply a drainage layer of gravel about five centimeters thick to the perforated base.
  • Mix the excavated earth with plenty of mature compost.
  • Put the buddleia in the planting hole and fill in the soil.
  • Gently step on it and water the root area thoroughly.

If desired, you can also mulch the root area with bark mulch or another suitable material.

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What is the best time to plant?

If possible, plant the buddleia - including the hardy species and varieties - after the ice saints in spring, when the ground is already slightly warmed and the danger of night frosts has been averted. Now the plant has a few months to grow in its new location in the garden until the first winter comes and the above-ground parts of the plant may freeze back.

The correct planting distance

In particular, the popular varieties of Buddleja davidii, with a stature height of up to 300 centimeters and a growth width of up to 200 centimeters, can take on quite considerable proportions, especially since the shrub is also quite fast-growing. Maintain a planting distance of around 150 centimeters for solitary plants, for a hedge or group planting, however, a distance of between 80 and 100 centimeters is sufficient. Smaller species, on the other hand, require significantly less space.

By the way, the buddleia can be planted very well under, as the shrub often remains bare in the lower area. Annual summer flowers are particularly suitable for this, but also low perennials.

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How do I transplant properly?

If the summer lilac is to be transplanted to a new location, this is easily possible. However, postpone this measure to May or early autumn, as repositioning in the middle of the vegetation period can quickly lead to problems due to the inevitable loss of roots. It is best to proceed as follows:

  • Cut the bush back vigorously by at least a third.
  • Tie the leftover shoots together at the top.
  • Use a sharp spade to dig a deep trench around the shrub.
  • Loosen the root ball in the earth with the help of a digging fork.
  • Lift this out together with the plant.
  • Plant the bush back in its new location.
  • Mix the excavated material with plenty of compost.

Also, give the freshly transplanted buddleia plenty of water to make it easier for it to grow. You should also water the plant more over the next few weeks.

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Watering Buddleia

Freshly planted buddleia should be regularly watered so that it takes root better. This is especially true in the summer months when it is hot and dry. Specimens cultivated in pots are also dependent on a regular water supply, as they cannot take care of themselves. However, waterlogging must not occur, as this in turn leads to root rot. Older summer lilacs that are already well established in their location in the garden, on the other hand, rarely need to be watered, for example during a long summer dry period.

In contrast to many other plants, you can easily supply Buddleja with hard water from the tap, as the plants prefer this.

Fertilize Buddleia properly

The summer lilac is also pleasantly undemanding in terms of nutrient supply: Only when planting and after pruning should you consider it with a generous shovel of compost and possibly a handful of horn shavings (€ 6.39 at Amazon *) in order to stimulate the subsequent growth. Only shrubs cultivated in pots should be fertilized every two weeks during the growing season with a liquid potted plant fertilizer that is more phosphorus than nitrogen.

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Cut Buddleia correctly

There are many good reasons for pruning Buddleia regularly. Above all, dead shoots should be removed regularly to keep the shrub continuously blooming. Once he puts his energy into the formation of seeds, the abundance of flowers is over.

Further pruning measures and, above all, their timing, on the other hand, are heavily dependent on the type and variety of buddleia. The often cultivated Buddleja davidii, for example, only develops flowers on this year's shoots and is therefore often placed “on the cane” in spring, ie cut back to a height of 20 to 30 centimeters above the ground. This measure is especially necessary when the above-ground parts of the plant have frozen back as a result of a cold winter and the shrub is therefore to sprout again. However, so that the buddleia does not bloom too late, you should prune it in April at the latest, or better still during a mild period in March.

Other species of buddleia should not be pruned as much. For example, Buddleja alternifolia only receives a clearing cut, which is carried out in autumn after flowering. Apart from removing too dense or dried out shoots, you can also shape the shrub a little, but you should not cut this year's shoots: the Chinese Buddleia will bloom on these in the following year.

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Propagate Buddleia

Although you can also propagate Buddleia from seeds (you have collected yourself), this type of reproduction is not suitable for single-variety progeny. If you value single-variety propagation without a surprise effect, you should cut cuttings in summer, plant sinkers or extract cuttings from the cuttings. The classic propagation of cuttings quickly shows success and works best according to this scheme:

  • In June / July cut semi-woody shoots without flowers.
  • These should be around four to six inches long.
  • Completely woody branches are not suitable, but can be used as cuttings.
  • Leave two to three leaves on the top of each cutting, remove the rest.
  • Cut these leaves in half to reduce the rate of evaporation.
  • Plant the cuttings one at a time in small pots with growing medium. (€ 9.05 at Amazon *)
  • Always keep the substrate slightly moist, but not wet.
  • Place a cut-off PET bottle or plastic bag over the plant.
  • Both improvised a mini greenhouse and must therefore be translucent.
  • Place the pot in a warm and bright, but not directly sunny place.
  • Ventilate the mini greenhouse daily.

As soon as the cuttings develop new shoots, they have developed strong roots and the protective cover can be removed. However, do not put these young plants in the garden yet, but maintain them for the first winter in a cool and light interior that is still frost-free.

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Diseases and pests

The Buddleia is a very robust plant that rarely gets sick or attacked by pests. Most problems arise as a result of improper care, especially if the shrub has been over-watered. Yellow leaves often indicate overwatering, and the shoots of the affected plant soon wilt and dry up despite apparently sufficient water supply.

Downy mildew, a fungal disease, can become a problem, especially in wet summers. Yellow spots on the tops of the leaves as well as a grayish-white fungal lawn on the underside are clear indicators of this common disease. Cut away the infected shoots generously and dispose of them with the household waste, but under no circumstances on the compost. In addition, the diseased plant should be sprayed with a brew of field horsetail broth, as this biological remedy, which is easy to make yourself, is quite reliable and helps against fungal diseases.

Buddleja davidii in particular often freezes back during the cold winter months, but this is usually not a problem - at least as long as the roots of the shrub are not affected. Cover the root area generously with a thick layer of fallen leaves and bark mulch in autumn to keep frost away and prune back the buddleia vigorously in spring. It will sprout again reliably and very quickly.

Of course, pests do not stop at an already weakened buddleia. Mainly aphids, but also gall mites and leaf miners cause problems for the shrub. Prevent an infestation by nurturing and caring for beneficial insects in your garden and offering you a comfortable shelter in a conveniently located insect hotel.


Young buddleia still need winter protection, especially in the first three years. After that, they are usually sufficiently hardened to withstand temperatures of down to minus 15 ° C.

Species and varieties

Of the numerous species of the Buddleja genus, B. davidii and the Chinese or alternate buddleia, B. alternifolia, are cultivated in this country. The variety of varieties is particularly high for Buddleja davidii:

  • 'Adonis Blue': beautiful, dark blue flower panicles
  • 'African Queen': purple to lilac blue flower panicles
  • 'Black Knight': very dark flower color from purple to dark purple
  • 'Cardinal': strong dark pink to purple flower color
  • 'Empire Blue': light blue-violet flower color
  • 'Pink Delight': beautiful, light pink flower color
  • 'Purple Emperor': dark, purple-red flower panicles
  • 'Summer Beauty': pretty, purple-violet flower color
  • 'White Bouquet': strong, pure white panicles of flowers

The yellow buddleia (Buddleja x weyeriana) comes up with the variety 'Sungold', which has a particularly striking, light yellow flower color.

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