Soils for Clematis
Clematis, the Queen of Vines, is grown in gardens around the world. A few myths surround its growing conditions, particularly around the soils for clematis. Contrary to popular belief, there’s a clematis for almost every garden, including plant hardiness zones 1 as well as poor soils.
Soils for clematis are not as clear cut as people make them out to be, which is why I looked into it. Why clematis? I developed a fondness for clematis vines when I gardened professionally in Vancouver, British Columbia. The sheer beauty and perfection of the clematis flower captivated my heart. Clematis’s versatility only added to its charm. It can be grown on walls and fences, interweaving through shrubs or even as a ground cover. As soon as I had some of my own outside garden space, I gave in to the lure of luscious purple blooms.
There’re many kinds of clematis. Three hundred species at least. Clematis can be deciduous or evergreen. They can also found as climbers, shrubs or herbaceous perennials. The Royal Horticultural Society’s (RHS) Plant Finder lists 2436 clematis species and cultivars!
Plant hardiness zones for clematis vines
Most clematis vines hybrids grow well in USDA Hardiness Zones 4 through 8 in the East and 4 through 9 in the West. Again, there are exceptions. There are clematis vines that grow well in Zone 10. From the hot, dry Californian climate to the humid hot Floridian summers.
Karen Dardick’s article, Clematis for the South, lists a couple of suitable clematis vines:
Clematis ‘Comtesse de Bouchaud’ (pink)
Clematis ‘Ernest Markham’ (red)
Clematis ‘Duchess of Edinburgh’ (white).
On the opposite side of the temperature scale, there are clematis vines that thrive in Zones 1 and 2. Heritage Perennials’ Perennial Planting guide lists a couple of species:
Clematis tangutica — Golden Clematis (yellow)
Soils for clematis
My first clematis was Clematis ‘The President,’ which received the RHS Award of Garden Merit in 1993. At the time, it was THE clematis vine to grow! I grew it in a large container filled with potting soil and fed with slow release fertilizer. I didn’t have to wait for very long for it to bloom. It bloomed. It flowered in its first year. I was in heaven.
Although I didn’t fully realize it at the time, growing the clematis in containers provided the vine its ideal growing conditions: moist, but well drained. Since it was growing up a trellis near my door, the pot stayed cool, but the vine grew into the sunlight. Growing in the soil is a little trickier. In common with many well-liked and used plants, many myths have been perpetuated about ideal soil for clematis as well as growing conditions.
What are these myths? The International Clematis Society listed two myths from John Howells’ book, The Rose and The Clematis as Good Companions.
1st soil myth
The first often told myth is that “Clematis likes its feet in the shade and its head in the sun,” is sort of true, but it’s not for the reasons you would usually associate with shadows.
“It is not the shade that the [clematis] roots require, it is the water that lies in the shade,” says John Howells.
Adding mulch around the clematis roots, which reduces water evaporation, is the best method. Mulch keeps the soil moist longer. Perfect for clematis.
2nd soil myth
The 2nd myth states that clematis prefers an alkaline soil since many clematis flourish in chalk soil.
Howells says it’s not chalk’s alkalinity that causes clematis to grow so well, it’s the deposits of WATER in the chalk.
Given enough water, clematis will flourish in most soil pHs, just not in extremely acidic or alkaline soils.
No doubt you’ve noticed a theme of exceptions with clematis. Another exemption is the need for MOIST, fertile soil. Sure, most clematis vines need moist, rich soil, but there are a few exceptions.
Clematis ‘Prairie Traveler’s Joy’ adapts to a wide range of soil conditions. It’s also very drought tolerant. Clematis tangutica — Golden Clematis — also tolerates a wide variety of soil, including poor soil.
The Royal Horticultural Society (RHS) recommends placing large-flowered spring blooming cultivars’ crowns 2-3” below the soil surface. But, the herbaceous & evergreen clematis species (i.e., C. armandii & C. cirrhosa) should have their crowns planted at soil level.
Planting deeper encourages shoots to grow from below ground level, and it also helps the plant to recover if affected by clematis wilt.
If growing organically use compost and chicken manure. You can also use rose/tomato fertilizer for containers i.e. 5-10-5.
If you have the space in your garden for a flowering vine, clematis is a good choice. Clematis comes in so many colors and shapes; you’re bound to find one that you like. Even if you have challenging soils or climate, you can grow clematis. You just need to pick the right one.
Howells, John. 1996. The Rose and The Clematis as Good Companions. Publisher: Garden Art Press
The Telegraph. Best clematis for your garden in pictures. Great photos!
Toomey, Mary and Everett Leeds. 2001. An Illustrated Encyclopedia of Clematis. Publisher: Timber Press
Valleau, John M. 2003. Heritage Perennial’s Perennial Gardening Guide. Publisher: Valleybrook International Ventures. Information now also found online at Heritage Perennials.