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Clematis is one of the most popular climbing plants because it has beautiful flowers that provide a very eye-catching display for any garden. The plants are typically very easy to cultivate but there’s a lot of confusion about when to prune and how to prune, and what to do about shoots that are dying. The most common problem is often wilting stems which are often blamed on clematis wilt, however, as you will learn, it’s often not the case at all.
- Powdery mildew
- Capsid bugs
Why are the leaves on my clematis turning brown?
If you have unstable growing conditions, especially in the hot sun or dry soil and it can cause physical damage to your stems and brown the leaves. It could also be capsid bugs eating away at the leaves, but this is something that is easy to spot because they often make many small holes and can cause the flower’s buds to abort. Try spraying with a pesticide.
Clematis prefer cool roots so planting in a position where the roots will be cool but the top section of the plant gets plenty of sun. If this isn’t an option in your garden, a solution could be to plant other plants around the base that can achieve this in a sunny spot. Applying mulch around the base and water regularly in dry spells can also help.
Why are my leaves curling and sticky?
If your plants have sticky leaves that are curled you probably have aphids. Aphids excrete honeydew and this is what causes that stickiness. It is important that you find the culprits and eradicate them entirely.
Younger shoots and leaves are particularly at risk, young growth shoots and leaves are particularly susceptible to aphids such as greenflies. These can be easily treated by spraying with a pesticide or spraying on soapy water is an old trick that can also be effective.
Why won’t my clematis flower?
If your clematis is not flowering properly it is probably the result of unsuitable growing conditions or incorrect pruning. These plants need moisture in the soil at all times but the soil needs to be well-drained. This means the roots need to stay cool and shaded otherwise they won’t flower properly. Moreover, if you accidentally prune at the wrong time of year you might remove the part of the plant that would normally produce flowers in the upcoming season. If you grow clematis in pots applying gravel on top of the soil can help keep the roots cool.
There is an actual disease called clematis wilt but its scientific name is Calophoma clematidina. This is a fungal infection and is often blamed for wilting stems. The best thing to do is to cut out any wilting foliage back to a healthy section. As there is no chemical control the best way to help prevent clematis wilt is to provide a favourable rooting environment, well-drained, moist soil and add a layer of mulch around the base.
Your plant might also suffer from a type of root disease known as honey fungus. This is actually the most destructive fungal disease in UK gardens. It can be identified by a white fungus underneath the bark where the disease attacks the roots and is a problem often found in very wet ground.
If you have container-grown plants or you have plants in damp soil that isn’t well-draining, your plant could have root decay from waterlogging. This is a potential problem with plants that have been put into a container that is too large in size, which is why we always recommend potting up into a slightly larger pot.
Fungal diseases (Powdery Mildew)
White, powdery mildew is one of the most common mildews for plants and can result from things like over-watering, the transfer of diseases or even unsuitable growing conditions. Powdery mildew is a fungal disease so if you notice any spots on your leaves, you need to take measures to eradicate them. Remove the affected growth and spray with a fungicide.
If you notice that the petals on your clematis are being eaten you probably have earwigs. There are a number of insects and pests that will feed on the leaves and damage them including caterpillars, moths as well as earwigs. If you have brown-edged holes it is probably the result of the capsid bugs we mentioned earlier.
If your shoots are wilting at the tips and starting to die back there are a handful of explanations, although you might need to do some detective work to uncover the real culprit. First and foremost, slugs and snails will eat your plant and they typically chomp away at the surface of your stem which is what provides that very pale appearance. The younger the shoots are, the more susceptible they are.
If you have container plants they are also particularly vulnerable to vine weevil grubs. These grubs will eat the roots and can cause your leaves to wilt. Vine weevil is a black beetle but they start out as white grubs that feed on roots which are the real problem. You can get a pesticide called Provardo bug killer that you use to drench the soil and kill the bugs.
If your clematis is producing flowers that have green petals it is probably the result of low temperatures. This is a common problem called clematis green petal. If this problem persists throughout the flowering time and the flowers become distorted for the entire blooming time, it might be a green flower disease. This is a very contagious disease that is caused by phytoplasma and any plants that are affected need to be destroyed immediately, so this is a disease you really don’t want to see.