The summer lilac (bot. Buddleja) is also known as the butterfly lilac and bears this name for a reason: the sweet-smelling shrub, which blooms magnificently in violet or blue tones and attracts countless butterflies that feast on its nectar. The blossoms are all the more lush the better the summer lilac is cared for. Incidentally, the species looks very similar to the widespread lilac, but is not related to it.

Butterfly bushes magically attract butterflies

Table of Contents

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  1. origin and distribution
  2. use
  3. appearance and growth
  4. flowers and flowering time
  5. toxicity
  6. Which location is suitable?
  7. substrate / soil
  8. pot culture
  9. Plant summer lilacs properly
  10. What is the best planting time?
  11. The right planting distance
  12. How do I plant correctly?
  13. Water summer lilac
  14. Fertilize summer lilac properly
  15. Pruning summer lilacs correctly
  16. Propagating Buddleia
  17. diseases and pests
  18. species and varieties

    19. origin and distribution

    There are around 100 different species of summer lilac (bot. Buddleja), which belong to the figwort family (Scrophlariacae). They 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, 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 it belongs to the olive tree family (Oleaceae).

    use

    The rather undemanding summer lilac fits wonderfully both as a solitary plant and in a group planting in full sun in the garden with poor, gravelly soil. The shrub cuts a fine figure in colorful beds of summer flowers and perennials 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 a hedge. Buddleia is also popular in Mediterranean-style gardens, for example in combination with other Mediterranean plants such as lavender, thyme, sage, etc. Together with other perennials that are popular with butterflies, such as asters or stonecrop, you create an oasis for the little butterflies that is frequented by birds .

    The species Buddleja davidii, of which there are numerous, colorful varieties, is particularly popular for the garden. The alternate or narrow-leaved summer lilac (Buddleja alternifolia) is also very suitable for garden cultivation, whereas the rare yellow summer lilac (Buddleja x weyeriana) should only be planted out in regions with a mild climate due to its lack of frost hardiness. However, all species are also ideal for keeping in buckets.

    appearance and growth

    The species Buddleja davidii is particularly well suited for the Central European climate zone with its sometimes severe and cold winters, of which there are numerous variants with different growth forms, heights and flower colors. The shrubs grow either broadly upright to squat - depending on the variety - and develop a funnel-shaped, loosely built crown with strong main shoots. The buds are attached to the loose side branches, which often bend slightly under this weight. On average, these varieties of summer lilac grow up to two meters high, although there are also tall variants with a growth height of up to four meters. Buddleja davidii is one of the evergreen species, because the grey-green foliage often stays on the shoots until frost and only dies with the first frost. In winter, the above-ground parts of the plant can freeze back, but the fast-growing shrub will sprout again in spring and quickly reach its old height.

    flowers and flowering time

    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 their lush splendor in various tones of white, pink, red and violet. After pollination - and insofar as the withered shoots are not cut away - capsule fruits develop, which contain many tiny and winged seeds.

    toxicity

    Unfortunately, what tastes so good to butterflies is poisonous to humans and pets. The popular species Buddleja davidii in particular contains toxic 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 accumulate in large quantities in the spring are not suitable for feeding large or small animals such as horses, cattle or guinea pigs, rabbits or turtles. However, you can put healthy parts of the plant in the compost without hesitation.

    Which location is suitable?

    As in its natural locations, the summer lilac feels most comfortable in a sunny and warm location. If necessary, a spot in the light semi-shade will also do, as long as the plant gets at least a few hours of sun there in the morning and evening. On the other hand, the location should not be shady: the summer lilac does not feel comfortable here, will stop growing and will not form any flowers.
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    substrate / soil

    Plant the summer lilac in a loose, well-drained and only moderately nutrient-rich soil, which can also be gritty and lean. Amend the soil during planting with mature compost to help the shrub take root in its new location. On the other hand, the summer lilac does not like heavy, loamy soil that tends to waterlogging. If necessary, look for another, 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 occur in the first place.

    pot culture

    Variants that are sensitive to frost, such as the globe summer lilac (Buddleja globosa) and the yellow summer lilac (Buddleja x weyeriana), should not be planted in the garden bed outside of regions with mild winters, but rather cultivated in a sufficiently large bucket. Other species - Buddleja davidii, for example - are also very suitable for keeping in buckets, provided there is enough space.

    Special, short-growing varieties are particularly suitable for this. Variants such as 'Purple Emperor' or 'Summer Lounge' only grow up to about one and a half meters in height and therefore do not need quite as much space for themselves - this fact is not entirely unimportant, especially on a cramped balcony. Choose a planter that is as large and deep as possible and made of a natural material such as clay or ceramic, so that the roots both have enough space and do not heat up in the summer heat. In particular, pots made of clay ensure air exchange 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 (€19.73). This increases the permeability of the substrate, although of course you must not forget the basic drainage in the pot. The bottom of the pot always needs a drainage hole through which excess water can flow into the planter or saucer. Water the plant regularly so that it neither dries out nor is constantly in wet substrate. In addition, regular fertilization is very important when kept in tubs, since the plant cannot take care of itself. Therefore, provide them with a liquid fertilizer for container plants every two weeks, but only during the growing season between April and August. Outside of this time, only watering is done, but no longer fertilized.

    Overwinter the summer lilac preferably cool and light, but frost-free in an unheated room.

    Plant summer lilacs properly

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

    • Dig a planting hole twice as wide and deep as the root ball.
    • Meanwhile, submerge the root ball in a bucket of water.
    • There it can soak up 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 two inches thick to the bottom of the hole.
    • Mix the excavated soil with plenty of mature compost.
    • Place the summer lilac in the planting hole and fill in the soil.
    • Gently tread them down and water the root area thoroughly.

    If desired, you can also mulch the root area with bark mulch or other suitable material.
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    What is the best planting time?

    Plant the summer lilac - including the hardy types and varieties - if possible after the frost saints in spring, when the ground has already warmed up a little and the danger of night frosts has been averted. The plant now 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 right planting distance

    In particular, the popular varieties of Buddleja davidii can grow to a height of up to 300 centimeters and a width of up to 200 centimeters, especially since the shrub is also quite fast-growing. Keep a planting distance of about 150 centimeters for solitaires, for a hedge or group planting, however, a distance of between 80 and 100 centimeters is sufficient. Smaller species, on the other hand, need significantly less space.

    Incidentally, the summer lilac can be planted very well, 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 plant correctly?

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

    • Cut back the shrub vigorously by at least a third.
    • Tie the remaining shoots together at the top.
    • Using a sharp spade, dig a deep ditch around the bush.
    • Use a digging fork to loosen the root ball in the ground.
    • Lift it out with the plant.
    • Replant the shrub in its new location.
    • Mix the excavation with plenty of compost.

    Also, water the freshly transplanted summer lilac plentifully to help it grow. You should also water the plant more over the next few weeks.
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    Water summer lilac

    Freshly planted summer lilac should be watered regularly so that it takes root better. This is especially true in the summer months when it is hot and dry. Specimens cultivated in tubs also depend on a regular water supply, as they cannot take care of themselves. However, there must be no waterlogging, as this in turn results in root rot. On the other hand, older summer lilacs that are already well established at their location in the garden only need to be watered rarely, for example during a longer summer dry period.

    Unlike many other plants, you can easily provide Buddleja with calcareous water from the tap, as the plants prefer it.

    Fertilize summer lilac properly

    The summer lilac is also pleasantly undemanding when it comes to nutrient supply: You should only give it a generous shovel of compost and possibly a handful of horn shavings (€32.93) when planting and after pruning to stimulate subsequent new growth. Only shrubs cultivated in tubs should be fertilized every two weeks during the growing season with a liquid tub plant fertilizer that is more phosphorus than nitrogen.
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    Pruning summer lilacs correctly

    There are many good reasons to regularly cut back summer lilacs. Above all, faded shoots should be removed regularly to keep the shrub continuously flowering. Once he puts his energy into the formation of seeds, the lush blooms are over.

    Other pruning measures and, above all, their timing depend heavily on the species and variety of the buddleia. The frequently cultivated Buddleja davidii, for example, only flowers on this year's shoots and is therefore often planted "on the stick" in spring, i. H. Cut back to a height of 20 to 30 centimeters above the ground. This measure is particularly necessary when the above-ground parts of the plant have frozen back as a result of a cold winter and the shrub should therefore sprout again. However, so that the summer lilac does not bloom too late, you should cut back in April at the latest, preferably during a mild period in March.

    Other types of summer lilac should not be cut back as much. Buddleja alternifolia, for example, only receives a thinning cut, which is carried out after flowering in autumn. Apart from the removal of shoots that are too dense or dried up, you can also shape the bush a little, but you should not cut this year's shoots: the Chinese buddleia will bloom on them in the following year.
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    Propagating Buddleia

    Although you can also propagate summer lilac using seeds (collected yourself), this type of propagation is not suitable for varietal offspring. If you value a single-variety propagation without surprise effects, you should cut cuttings in summer, plant lowers or obtain cuttings from the cuttings. The classic cuttings propagation quickly shows success and works best according to this scheme:

    • In June-July, cut semi-lignified shoots without flowers.
    • These should be about 10 to 15 inches long.
    • Completely woody branches are not suitable, but can be used as sticks.
    • Leave 2-3 leaves on the top of each cutting and remove the rest.
    • Halve these leaves to reduce the rate of evaporation.
    • Plant the cuttings individually in small pots with growing substrate.
    • Always keep the substrate slightly moist, but not wet.
    • Put a cut-off PET bottle or plastic bag over the plant.
    • Both improvise a mini greenhouse and must therefore be translucent.
    • Place the pot in a warm and bright spot, but not direct sunlight.
    • Ventilate the mini greenhouse daily.

    Once 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 just yet, but rather keep them frost-free in a cool and bright indoor space for the first winter.
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    diseases and pests

    The summer lilac is a fairly robust plant that rarely gets sick or attacked by pests. Most problems occur as a result of improper care, especially if the shrub has been overwatered. Yellow leaves often indicate overwatering, and the shoots of the affected plant soon wither and dry up despite apparently sufficient water supply.

    Downy mildew, a fungal disease, can become a problem, particularly in humid summers. Yellow spots on the tops of the leaves, as well as a greyish-white patch of fungus on the undersides, are a clear indication of this common disease. Cut away the affected 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 decoction of field horsetail broth, as this biological agent, which is easy to produce yourself, is quite reliable 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. In fall, cover the root area generously with a thick layer of foliage and bark mulch to keep frost at bay, and prune buddleia vigorously in spring. It will drive out again reliably and very quickly.

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

    tips

    Especially in the first three years, young summer lilacs need winter protection. After that, they are usually sufficiently hardened to withstand temperatures of up to minus 15 °C.

    species and varieties

    Of the numerous species of the genus Buddleja, B. davidii and the Chinese or alternate summer lilac, B. alternifolia, are cultivated in this country. The diversity of varieties is particularly high with Buddleja davidii:

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

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

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Animals in the garden