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Curled leaves on summer lilac put the gardener on alert. With this behavior, the opulent flowering shrub signals that the general conditions are out of balance. Various causes can cause the frequent damage. The range of possible triggers extends from frost damage to care errors to pest infestation. A step-by-step analysis by process of elimination leads to the solution to the problem. Read this guide for 5 solutions. This is to be done when the leaves are curling up on the Buddleja.
Buddleia Leaves are curling up
Buddleia inspires as a richly branched, deciduous shrub with a funnel-shaped stature. Stiffly upright main shoots are characteristic, whose side branches overhang picturesquely. Premium varieties for the garden stretch up to 400 centimeters into the sky. Dwarf varieties remain at a height of 60 to 100 centimetres, ideal for cultivation in tubs. From July to October, the flowering shrub adorns beds and balconies with large, curved panicles of flowers that magically attract butterflies, bees and bumblebees. Buddleja owes its second name butterfly bush to this property.
The summer fairy tale of flowers depends on a whole group of lanceolate leaves to ensure the supply. The up to 10 centimeters long, tapering leaves appear punctually at the beginning of this year's growing season and pave the way for the coming blossom festival. If leaves on the buddleia roll in before or during the flowering period, there is an urgent need for action. Because without its foliage, the ornamental tree lacks the capacity for the growth of the up to 30 centimeter long flower panicles.
Summer lilac, Buddleja
Causes & Measures
frost damage
When summer lilacs sprout their leaves, the danger of delayed ground frosts hangs over the shrub like a sword of Damocles. A single frosty night is enough to cause considerable damage to the young foliage. If only the edges of the leaves curl up, there is no reason to worry. With this strategy, a butterfly bush protects itself against frost and cold easterly winds. As soon as the weather adjusts to the calendar, the edges of the sheets unroll again. Severe or prolonged frost, on the other hand, gives the young foliage no chance of survival. Typical signs of damage are severely curled, limp hanging and dried leaves. The solution to the problem is a targeted pruning back into the healthy wood. How to do it:
- Cut back buddleia with frost damage in June
- Shorten shoots with frozen leaves down to healthy wood
- Set the scissor blades a few millimeters away from a bud or healthy leaf
With a vitality test determine the transition from damaged to healthy wood. Scrape off some of the bark with your fingernail or tip of a knife. If dry, brown tissue emerges, you are in the dead shoot area. Light green fabric signals that floral life is pulsating at this point. Buddleja is equipped with a good-natured pruning tolerance. If you find yourself forced to cut back radically, the shrub will sprout again willingly, as long as stubs with a few buds, leaves or dormant eyes remain.
drought stress
Summer drought stress is one of the most common causes of curled leaf blades on butterfly bushes. Young shrubs whose root system is still developing are primarily affected. If there is no rain for a long time, older specimens are also not spared from the damage. If the summer lilac rolls up its leaves in the middle of the flowering period, it wants to be watered thoroughly. This applies equally to shrubs in beds and tubs. How to do it right:
- Best time is early morning or after sunset
- Fill the watering can with tap water
- Pull the spray head off the jug spout
- Pour directly onto the root disc without wetting foliage or flowers
If small puddles form in the bed, the watering process is stopped to prevent waterlogging. The water requirement in the bucket is covered when the first drops run out of the bottom opening. Please avoid targeting your summer lilac with the water hose. Damp leaves do not roll up again more quickly, but primarily offer an ideal target for diseases and pests.
tip: Butterfly bush (Buddleja davidii) blooms most beautifully on this year's shoots. A strong pruning in the spring is therefore part of the obligatory care program. Alternating summer lilac (Buddleja alternifolia) blooms on last year's shoots and is thinned out a little from time to time.
Infestation with harmful soil fungi
If you can rule out the two most common causes, frost damage and drought stress, then focus on the root area. Buddleia curl up leaves when diseased root strands stop working. The focus is on the root fungus Pythium. The egg fungus species is closely related to the causative agents of dreaded diseases such as powdery mildew or blackleg. Fatally, Pythium is always up to mischief underground, so that you only discover an infestation with the help of consequences, such as rolled-up leaf edges. All important ornamental plants belong to the group of host plants, so that summer lilac is not spared. The suspicion is substantiated when other symptoms appear, such as wilting, yellowed leaves and detached sections of bark.
To date, no fungicides are available for controlling root fungi on buddleia. Conventional sprays against fungal infection do not achieve any significant results. In the early stages, however, there is the option of biological control methods. The goal is sunnier, drier conditions that deprive Pythium pathogens of their livelihood. In the following, we have compiled tried-and-tested procedures for you in gardening practice:
- Keep soil and substrate slightly drier
- Enrich heavy, moist soil with sand
- Cut back shadow-casting neighbors
- Relocate potted plants to a sunnier spot
- Water repeatedly with field horsetail broth to strengthen the body's defences
For the ecologically managed home garden, the specialist trade offers a biological spray. Prestop from Biofa contains natural antagonists of Pythium and does without chemical ingredients. Special bacteria and fungi parasitize the pathogen and prevent further growth. Reliable empirical values about the clout of the bio-preparation are currently still being collected.
aphids
When examining your buddleia for causes of curled leaves, a magnifying glass should be handy. Deciduous trees often roll up their leaf blades as a defense against aphids. The tiny pests prefer to colonize the undersides of the leaves in order to feast on the plant sap. They leave small yellow spots at the taps, which are also difficult to see with the naked eye. If you have tracked down aphids, a tried and tested home remedy is available as a solution to the problem. How to do it:
- Rinse off the affected shrub in advance with as strong a jet of water as possible
- Protect the soil from excessive moisture with foil
- Pack tub with root ball in a plastic bag
- Heat 1 l of water and dissolve 30-40 g of pure curd soap in it
- Ideally add a few dashes of spirit
- Pour the cooled soap solution into a handheld or pressure sprayer
aphid infestation
Spray the aphid-infested butterfly bush with soapy water every 3 days. Treat the top and bottom equally. Please only use the home remedy when no rays of sunlight are hitting the shrub.
voles
If there are voles roaming your garden, the succulent roots of a summer lilac are at the top of the menu. If you were able to dismiss all of the reasons mentioned as not applicable, then the voracious rodents move into your sights. Nibbled root strands transport little or no water and nutrients towards the foliage. As a result of the limited supply, the leaves are curling up. Instead of spending weeks on control strategies, get the root ball to safety. That is how it goes:
- Cut off the root disc with a sharp spade
- Radius corresponds to half to two thirds of the growth height
- Lift root ball out of the ground
- Line the pit with vole wire or a vole basket
- Plant butterfly bushes again and water generously
Transplanting is an effective solution to the vole problem when the buddleia in question is five years old and younger. However, older shrubs rarely survive the procedure unscathed. Instead, use tried-and-tested strategies to keep the pests away permanently. For example, fine vole noses cannot endure strong smells. Fumigation with smoke cartridges made from lavadin oil drives away the rodents never to be seen again. A mixture of thuja plant manure and castor oil also achieves good deterrent results. Once the pests have run away, the roots recover quickly and rolled-up leaves on the summer lilac are a thing of the past.