Clematis require alkaline soil. For most areas of Connecticut, that means adding lime, but a soil test is the only way to determine if you need to add lime and how much. They also need plenty of moisture and they like to grow into the sun but keep their roots cool. This can be accomplished by mulching or by placing other plants to grow around the base of the vines and shade their roots.
Stem rot, also called Clematis wilt, is the most common problem of clematis. The plant will appear to be wilting without evidence of mechanical damage (i.e. severed stems). To prevent this, use coal ashes, a zinc collar, or sand in an inverted flower pot (the plant grows up through the drainage hole) at the base of the plant. If stem rot does occur, do not plant another clematis in the same spot. Since it happens in large flowering varieties, plant small flowering types to eliminate the possibility, ex. Clematis viticella.
There are three basic types of Clematis:
1. Type 1 blooms only on last year's wood, meaning that the flowering shoots come off the vines that grew the summer before. This type blooms in late spring and early summer and is done blooming by the time July rolls around. It does NOT repeat bloom in late summer and all fall. Type one is usually very, very vigorous. An example of this type is Clematis montana ‘Rubens’. Leave
Type 1 Clematis alone in the early spring, even if it's a tangled mess. If you prune it, you will cut off most of last year’s wood and dramatically or completely reduce this year’s flowers. Once it has finished blooming in mid-summer, prune it immediately, as hard as you want. Take off the wild shoots. Thin out the tangled vines. Create a good framework for the vine. It will then continue to grow the rest of the season and you should leave it alone to form a good crop of next year's flowering wood.
2. Type 2 blooms on both on last year's wood and this year's wood. They bloom in the spring, early summer, late summer, and fall. Though they don't bloom as heavily, all at once, they are constantly pushing out flowers. You can prune Type 2 plants in one of two ways: a) If the vines are young, you may want to leave them alone. Cut off only the obviously dead wood. WAIT to do this until the leaves sprout, as dead looking vines usually are not! This light trimming means that you will enjoy a nice crop of early blooms. After that, the vines will grow vigorously. You can trim them back at any time up until mid-summer. The new growth that forms will continue to push out flowers. b) The second method of pruning Type 2 Clematis is the drastic cutback. If your Type 2 Clematis is a tangled mess (such as a dangling glob of dead and live vines pulling down the string suspended on your lamp post) and you can't stand it anymore, cut it back very hard in the spring, to within a few feet of the ground. You will sacrifice the first flush of early summer blooms but you will have a magnificent late crop on a very neat, properly tied-up vine.
3. Type 3 blooms only on this year's wood. The time to prune them, therefore, is early spring. You can cut them back really hard if you want; it won't hurt them, trust me! A perfect example is Sweet Autumn Clematis, Clematis paniculata, a prolific vine covered with sweet-scented, tiny white flowers in late August and September. Cut it back to a low woody trunk in late March and it will quickly re-grow and be a vigorous, full sized plant by mid-summer. Type 3 Clematis varieties only bloom from July onward; they are not spring or early-summer bloomers.
How do I know what kind of Clematis I have? Inevitably, the next question is "How do I know which kind I have?" If you know the name, you can look it up online or in a good reference book. If you don't know the name, you must be observant. For this year, don't do any drastic pruning. Just watch the plant and record when it blooms. Look closely at where the flowers are coming from. Do they sprout from older looking, woody stems? Or do they come from fresh, young growth? By careful observation, you should be able to figure out which kind of Clematis you have and thus how to prune it.
Clematis blooming on last year’s wood: (Type 1)
C. alpina varieties
C. macropetala varieties
C. montana varieties
Clematis blooming on both last year and this year’s wood (Type 2)
C. florida ‘Sieboldii’ Clematis varieties:
‘Belle of Woking’
‘Duchess of Edinburgh’
‘Lady Betty Balfour
Clematis blooming on this year’s wood (Type 3)
C. languinosa varieties
C. viticella varieties
‘Comtesse de Bouchard’
‘Hagley Hybrid’ ‘
‘Ville de Lyon’
In an effort to provide horticultural information, these educational documents are written by Nancy DuBrule-Clemente and are the property of Natureworks Horticultural Services, LLC. You are granted permission to print/photocopy this educational information free of charge as long as you clearly show that these are Natureworks documents.