Clematis are relatively easy to grow and care free. The one exception is clematis wilt. It is a frustrating problem because there doesn't seem to be any clear understanding or consensus among the experts about clematis wilt and what you can do to try to manage the problem. Even with the threat of wilt, clematis are well worth growing, offering incredible blooms on vigorous vines.

What are the symptoms of clematis wilt? Wilt affects plants very suddenly, frequently going from a healthy, full plant to totally wilted and brown in just a few days. It typically hits the whole plant at one time, but sometimes it is limited to the foliage attached to a single stem or area. Clematis wilt most frequently shows up in early to mid-summer.

What causes this problem? Even the exact cause is debated by the experts. The apparent cause is a fungus, but why one plant gets it and another doesn't is a mystery. What seems to be the most likely explanation has been offered by Jim Fisk, author of Clematis, Queen of the Climbers. He theorizes that clematis wilt isn't simply a fungal infection, but a failure of the stems to carry enough water to the foliage when the plants are in full leaf and the weather is stressful. The fungus might be after the fact, instead of the cause. This would help explain why clematis wilt is much worse some years than others.

What are some of the other possible explanations? At one time, wilt was believed to be transmitted by grafting, but clematis is seldom grafted any more and wilt is still a problem. Some experts believe it is one of several fungal diseases that enters weakened stems that have been injured or cracked, often simply by the wind.

Has it always been a problem with clematis? The earliest references to clematis wilt seem to be around the turn of the century. It became such an extensive problem that until the advent of broad spectrum fungicides, most clematis growers had given up. Clematis are once again popular and spectacular, but wilt can still be a problem.

Tell me what I can do to help prevent wilt on new clematis that I am planting. When you are planting clematis, there are several steps you can take to minimize the chance of getting wilt, or at least minimize how much damage it might do. Start by siting the clematis correctly. It prefers to grow where it will receive full day sun, but the roots need to remain cool. If the base of the plant is not shaded by something growing nearby, this can be accomplished by mulching the root system with an organic mulch such as shredded leaves, cocoa bean hulls or shredded bark. Another advantage you can give the clematis is to plant it deeply.

Exactly how deep should it be planted? When you plant clematis deep enough to put two sets of leaves (or leaf nodes) under the surface of the soil, you give the plant an insurance policy. Dig the hole deep enough to allow the first two sets of leaves to be completely underground. Fill the hole carefully around the slender, brittle stems. If a clematis planted this deeply is hit by wilt, it will usually come back from below the ground. If the clematis dies down to the ground, mark the spot and be patient, it may take up to two growing seasons for the plant to re-sprout.

Should I amend the soil? Clematis will grow best and be the most resistant to wilt if it is grown in deep, humus-rich soil. Unless you are fortunate to have great soil, you will probably need to amend the soil. What you use will depend on your type of soil. If you have sandy soil, mix it 50/50 with peat moss, manure, compost or a combination of these. If you have a clay soil, mix it 50/50 with coarse sand and coarse compost. Avoid adding peat moss to clay soils since it may retain so much water that the roots drown or rot.

If the wilt is caused by the vine's inability to carry enough water, is there anything I can do to help? Be sure the plant is soaked before you plant it and make sure any circling roots have been loosened. As the plant enters early summer full of leaves and buds, be sure it is watered regularly. Water it thoroughly and deeply, but avoid keeping the soil soggy. Just how much water will depend on the soil type. Often sandy soils will be dry a foot or so down even when the surface is damp, so thorough watering is essential.

If my clematis gets wilt, is there anything I can do? Once you have determined the clematis has wilt and has sustained permanent damage, remove all the damaged leaves and stems including those that have fallen. Be extremely careful not to injure any delicate stems that are still viable, especially at the base of the plant. After cleaning it up, make sure it is thoroughly watered. Drench the soil and base of the plant with a systemic fungicide.

Is there anything I can do to try to prevent wilt on the clematis I already have growing? As a precaution, a systemic fungicide should be applied in early spring before the new leaves emerge, monthly throughout the growing season and again in the fall after you have cleaned up the fallen leaves. Make sure it stays well-watered, especially during the hot, stressful parts of the season. In sandy well-drained soils, fertilize clematis with a water-soluble food such as Bachman's Mighty Bloomä every 2-3 weeks from spring until mid-August. In heavier soils, either fertilize less often (every 3-4 weeks) with Mighty Bloomä or use an all-purpose granular garden fertilizer such as Bachman's Garden Food 10-20-10.

Additional Bachman's Information
Clematis Basics
Pruning Clematis
Fungicide Basics
Chemical Basics
All About Watering
Fertilizing Annuals and Perennials

Recommended Products
Bachman's-Grown Clematis
Trellises and Plant Supports
Organic Mulches
Fungicide
Sprayers and Watering Cans
Quality Soil Amendments

©Bachman's 2007