by Dr John Howells

First published in Garden News, July. 27th 1999

Growing clematis is surrounded by myths, most of them wrong. Even planting has a myth. You should plant deep it says. That is wrong too.

The myth originates from the grower Rowland Jackman who, faced with wilt in his clematis, thought that if he planted deep this might cause extra shoots to come from the soil and these would act as a reserve should the main stem get wilt. No one has ever shown it works.

There are strong arguments against doing this. The most nutritious soil is near the surface and that gives your clematis the best start. If you want extra shoots then Jim Fisk showed years ago you can get them very simply by pruning the plant after putting it in the ground. Now that we know more about wilt we know that the affected node is often a bottom one; if you plant deep you will pull that node into the soil and increase the risk of wilt.

But the final argument is compelling. With a group of experienced clematis gardeners I explored which group of clematis got wilt. The answer was quite clear and confirmed by other researchers recently. The affected group are the Early Large Flowered group (the 'Nelly Moser' group). So why plant the other eleven groups deeply when they don't get wilt anyway? But even with the wilting group, planting deep won't help.

So plant clematis as you would any other shrub. If you have good soil make a hole 1.5 ft (45cms) across and 2ft (60cms) deep. Place your plant in it so that the crown of the plant is covered by an inch of soil. Make sure the top foot of the soil goes back to the top of your hole. Clematis like a good mulch to keep the soil moist. You can use for this purpose peat, lawn mowings, compost, manure, etc. Make sure manure does not touch your stems. A very effective mulch is a piece of plastic, which you can cover with wood chippings, grit or stones. The best mulch of all is a patio stone layer with a clematis in a cosy hole in it (far, far, better than a container which is the worst spot for a clematis).

All this is all right if you have good soil. Many of us don't. You may have very light sandy soil like mine. Here you need to improve the water retention and nutrition of the soil in your hole by adding old manure, compost, peat and a couple of handfuls of bonemeal or 'Growmore', well mixed in. Mulching is very important in a light soil.

Conversely, you may have a heavy clay soil. The problem here is getting good drainage. Roots need oxygen and they won't get it if they lie in a pool of water. Supply drainage at the bottom of your hole with a 6in (15cms) layer of broken pots, stones, grit or sand. Brother Stefan Franczak, the great Polish clematarian, can't get these and uses cut up wooden stems.

The clematis is safely in the hole. What now? Here we turn back to Jim Fisk and his pruning of new plants. It is hard on you having just bought this plant and looking forward to seeing a flower, to be told that you now have to prune off all the stem except the first 6in (15cms). If you have to, and I can understand it, let a bloom flower, get the joy of it and then prune to help your plant. You prune above the first node, at about 6-12ins (15-30cms). Two things will happen. The plant may throw up more plants from the soil and give you a strong plant for years to come. The second event is that at the node two branch shoots will appear. Let these two grow for 2ft (60cms) or so and then prune them above a node again. Soon you will have four shoots. Keep doing this and you will have a nicely spread out plant.

Here is some more bad news. If your nerves can stand it prune all the shoots on your plant at the start of the second year also. You patience will be rewarded with a magnificent plant that all the neighbours will come to see.

Frequently we want to plant a clematis to grow on a wall either on its own or with another climber. Near walls the soil is often poor as it gets no attention, little water, the wall may extract what little water there is and the foundations of the wall may be under this strip. So put your plant at least 2ft (60cms) away from the wall, and lead it to the wall on a cane or string; clematis have no problem with this. Out there the plant has light, water and nourishment and will be as happy as the day is long.

But what if you can't plant 2ft (60cms) from the wall? You may only have a strip of about 1-1.5 ft (30-45cms) wide. Can you plant a clematis in that? You can. But only if you regard that strip as if it were a container. So you give it container attention. This may mean removing the old soil and replacing it with your favourite soil mixture. Check that the foundations of the wall don't prevent good drainage. Protect the wall with slates or plastic as you are going to use a lot of water in this strip. You may need to water at least once a week or every day in a dry spell. Some watering in winter is required, as winter rain may not reach this strip. Can you over water? You can. If you have not checked drainage the roots of the plant will be in a pool of water. The plant will wilt. Thinking it is dry you will give it more water and end up killing it.

A vital part of your planting is to label. Tie the label not to the plant but to something nearby. Then you go back to the house and do the most important action in the whole planting programme! Mark your clematis on your garden plan. Labels walk, your plan won't.

Reproduced by kind permission of Garden News.

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