All you need to know about planting, growing and caring for clematis in our detailed Grow Guide.
Clematis are popular perennial climbers, providing height and colour throughout the season. They look particularly good with roses. Theres a huge variety of clematis to grow, with flowers ranging in size from small bells to large dinner plates.
Clematis can be good for wildlife, clothing walls, fences and trellis with leaves and flowers, which provide shelter for insects and sometimes birds. Some clematis flowers are visited by pollinators, while the fluffy seedheads of Clematis tangutica cultivars may be used as a nesting material by house sparrows.
Clematis are beautiful flowering vines that can add incredible color and interest to any garden. However, they do require some special care, particularly when it comes to their root systems. Clematis roots need to be kept cool in order to avoid clematis wilt, which can be fatal to the plant. With the right techniques, keeping clematis roots cool is easy. Here’s everything you need to know.
Why Keep Clematis Roots Cool?
Clematis wilt is a fungal disease that affects the vascular system of the plant, preventing water and nutrients from reaching the leaves and flowers. It causes the foliage to droop and dry out and can quickly kill the plant if left unchecked.
This fungus thrives in warm, moist conditions. Therefore, one of the best defenses is to keep clematis roots as cool as possible. Cool soil temperatures help suppress the fungus and prevent it from spreading through the plant’s system.
In addition, clematis simply prefer cooler root zones and will be healthier and happier plants when provided with the right conditions Avoiding clematis wilt is just one of the benefits of keeping roots cool.
Planting Tips for Cool Clematis Roots
The easiest time to set up the right conditions for cool clematis roots is at planting time. Here are some tips:
-
Plant deeper Set the crown of the clematis 6-8 inches below the soil surface, This automatically places the roots further down into cooler earth
-
Prioritize shade: Choose a planting site that will be shaded, especially during the hottest part of the day. The north or east side of a trellis, fence or home is ideal.
-
Use light, airy soil: Prepare a loose, well-draining soil mix using compost and sand. Dense or heavy clay soils retain more heat.
-
Mulch well: Apply 2-4 inches of an organic mulch like shredded bark around the plant. The mulch insulates the soil and keeps it evenly cool.
-
Provide support: Give the clematis a support structure to climb right away before excessive foliage growth shades the roots.
Caring for Established Plants
Keeping the roots of established clematis plants cool requires diligent care and monitoring:
-
Mulch annually: Replenish the mulch layer each spring, after pruning. Organic mulch will break down over time.
-
Water judiciously: Avoid overwatering, which leads to saturated soil that retains heat. But don’t underwater either. Even moisture is key.
-
Monitor for weeds: Remove weeds promptly, especially grass, which conducts heat into the soil.
-
Prune strategically: Pruning promotes air circulation and avoids crowding. But don’t prune too heavily. Some foliage shade is beneficial.
-
Check soil temperature: Use a thermometer probe to check the temperature a few inches down. Ideally it should be 60-75F.
-
Treat affected plants: Disinfect tools after pruning wilt-infected plants to avoid spreading. Remove and destroy infected material.
Helpful Methods to Cool Clematis Roots
If you’re battling excessively hot soil, there are some additional methods to try to cool down clematis roots:
-
Shade or paint terra cotta and plastic nursery pots with light colors to prevent absorption of heat. Or place pots in saucers.
-
Use soaker hoses for irrigation to keep water off foliage. Avoid wetting leaves which can lead to fungal issues in heat.
-
Apply organic compost as mulch instead of bark chips. Compost contains beneficial microbes and stays cooler.
-
In extreme heat, construct temporary shade structures using shade cloth over plants. Remove in cooler weather.
-
For potted plants, nestle pots into larger containers filled with packed earth or mulch. The surrounding soil will moderate root zone temps.
-
Explore new clematis hybrids bred to be more wilt resistant. Proven winners like ‘Hagley Hybrid’ and ‘Polish Spirit’.
Ideal Conditions for Healthy Clematis
When shopping for clematis, selecting varieties suited for your climate is important. But creating the ideal growing environment will still make a big difference in the plant’s health and performance.
To summarize, here are the recommended conditions for keeping clematis roots happily cool:
-
Soil temperature: 60-75°F
-
Sunlight: 6+ hours of sun, with shade from hot afternoon sun
-
Soil: Loose, light, moisture-retentive soil high in organic matter
-
Mulch: 2-4 inches of organic mulch
-
Moisture: Evenly moist, never waterlogged or bone dry
Give your clematis the right start and diligently tend the soil environment surrounding their roots. Taking these steps to keep roots cool will help your clematis thrive for many seasons of spectacular blooms.
Growing clematis: problem solving
Clematis wilt can cause huge problems for clematis, growers, causing clematis to die suddenly without apparent reason. Larger flowered types are the most likely to be affected. It’s easy to spot as plants quickly wilt. Clematis wilt is a fungal disease. Prune out all affected stems and burn them.
Clematis are also prone to an attack from earwigs, which chew holes in the flower petals. This damage is only cosmetic and doesnt harm the plant. If youre really concerned you can create earwig traps by pushing a 1m long cane into the ground next to the clematis. Stuff a plastic plant pot with straw and place it upturned on the top of the cane. Earwigs will use this as shelter during the day, giving you the opportunity to catch and rehome them.
Rabbits, mice, slugs and snails may also be a problem. Protect young plants to give plants a good start.
Choosing the right clematis
Theres such a wide variety of clematis available, that its important you choose the right clematis for the spot you want to grow it in. Some clematis, such as Clematis montana, are extremely fast-growing and vigorous, and are suitable for covering an unsightly wall or shed in a short space of time. Other clematis have a much less vigorous growth habit, and are therefore suitable for growing in pots – look for growth habit on the label or varieties such as Clematis ‘Blue Dwarf’, which indicates a less vigorous habit.
Ther are plenty of clematis varieties suitable for sun and shade, so again check the label to see how well suited your clematis is to the spot you have in mind.
Lastly, consider how much care you want to give your clematis. If youre happy pruning your clematis annually, then Group 3 clematis are perfect for you. However, if youd like to keep pruning to a minimum then opt for a Group 1 or Group 2 clematis.
How to use a clematis root protector
FAQ
What to plant to keep clematis roots cool?
Both herbaceous and hardy perennials can be counted on to shade the base of Clematis vines, keeping their roots cool. Coneflowers, Daylilies, and Penstemon are great choices for extra hot and sunny spots. They will gently spread with no risk of overwhelming neighboring plants.
How to keep roots cool?
To keep plant roots cool, especially during hot weather, consider using mulch, providing shade, or clustering potted plants together.
How to shade the base of clematis?
Always plant shallow rooted perennials or seasonal bedding plants around the base of a clematis to shade the roots of the plant.
How to cover clematis roots in pots?
Clematis are best when their roots are shaded; so add some additional shallow rooted plants around the root system, either perennials or seasonal bedding plants. This creates a microclimate which clematis really enjoy, it also adds extra colour and interest.