Growing Clematis - A Step-by-step Guide

How to Grow Clematis

Index...

How to Plant Clematis in the Ground

How to Grow Clematis in Pots and Containers

Overview: How to Prune Clematis

How to Prune Group 1 Clematis

How to Prune Group 2 Clematis

How to prune Group 3 Clematis

How to Plant Clematis in a Flower Bed

Clematis will grow well practically anywhere if you provide five things: soil preparation, planting depth, adequate water, cool temperature for the roots and the first prune.

Soil Preparation

Clematis demand good drainage and do well on chalky or sandstone soils because the soil retains moisture but never puddles.

If you are on heavy clay, it's best to plant up on a slope and dig a relief trench away from the planting hole and down the slope to help water movement. If none of that is possible, make a good-sized mound - say 20cm (12") tall and twice as wide, and plant into that. Remember that the way to improve drainage in clay soil is with mostly grit and a bit of sharp sand, not smooth sand (AKA builder's sand) or compost etc.

• Dig a decent hole, about twice the width of the pot, and half as deep again is plenty.

• Remove all roots, weeds, stones and other rubbish and improve the soil with well-rotted manure or compost unless you are planting into clay soil, in which case add grit.

• Use either rootgrow or bonemeal when planting, but not both.

• Pinch off any leaves that will be buried when planting is finished.

• Water the plant well and remove it from its pot.

• Without breaking any, carefully tease out a few of its roots to help them out of the rootball and into the surrounding soil.

Plant Clematis Deep

Planting deep promotes vigorous growth from below soil level, which lessens the risk of diseases and means they will cover whatever you have planted them against that much faster.

For clematis in 2 or 3 Litre pots: The crown of the plant (where the stem/s emerge from the compost in which it was grown) should be at least 3-4 inches (8-10 cm) below soil level. A clematis with a really strong, woody stem can go about 6" / 15cm deep.

For clematis in 9cm pots: Still place these younger plants deep in the hole, but do not return the soil all the way up over the stem until it has become woody, which is usually the winter following planting.

Remember to Water!

Until a clematis has established and is growing away well, it will need plenty of water: they are thirsty plants and their roots were planted deep, so a light watering may not reach down far enough.

If in doubt, inspect the soil down to about 3 inches: if it's dry to the touch, it's definitely time to water.

Keep the Roots Shaded & Cool

Clematis love the sun on their vines above ground - the flowers of a few varieties will fade in direct sunlight, but still a very light, airy place is good.

The roots hate warm and dry soil. They must be kept shaded and cool. The traditional method for achieving this is covering the root area with loose paving, stone slabs, or bricks to shade the soil above the root zone thoroughly.

Just as effective are shallow-rooted ground cover like grasses, small shrubs like Hebes, ferns, or a nice Sedum like Rose Carpet - anything that won't compete for nourishment with the deep roots of the clematis. Planting ground cover to shade clematis roots has the benefit of covering what the late Christopher Lloyd described as a clematis's bad legs.

First pruning

It is tempting to plant your lovely, leggy (see above) clematis and let it get on with it. In fact, all newly planted clematis, regardless of their pruning group, benefit from being cut back to just above a leaf node no more than 12" off the ground - 6" is even better.

This first prune encourages the plant to sprout from the base, giving you a much bushier, healthier plant.

If you forget, then let it flower and sometime between planting and the following November, cut them back hard.

After this first prune, follow the pruning instructions according to their pruning group.

Have a look at our quick planting clematis in the soil video.

How to Grow Clematis in Pots & Containers

Growing clematis in a nice big pot is necessary on terraces, patios, balconies and so on, and where poor drainage or a high water table makes the soil unsuitable.

Clematis demand good drainage, so they are happy in pots, but they won't tolerate drying out or their roots overheating in summer.

Best Clematis Varieties for Growing in Pots

Any clematis can grow in a suitable container, but the easiest to manage are in pruning group 3. They flower on the growth of the current year and are pruned back yearly in late winter to 12-18" above soil level. This means their supports can be repaired, and the plant can be moved around as necessary - that's not really possible with a giant Montana!

Dainty varieties that reach less than about 2.5 metres can realistically be supported by a sturdy wigwam of tall bamboo canes tied around the outside of the pot if there is nothing else around, as long as the pot itself is not going to topple over. Have a look at White Prince Charles, Comtesse de Bouchaud, Duchess of Albany, or Hagley Hybrid for inspiration. Also, consider anything in the Boulevard or Tudor Patio collections, which are more like shrubs than climbers - try Ooh La La, Parisienne, Sally or the tiny, trailing Bijou.

Best containers for growing clematis

To shield the roots from hot conditions, materials that conduct heat slowly, such as thick pottery, stone, wood, or thick, insulated plastic, are much preferable to metal or cheap, thin plastic. Light, reflective colours are better than dark ones.

You should always keep the container in full shade. Putting the pot inside a cover and positioning it at the North side of other pots helps a lot.

Drainage is key

Most containers have good drainage, but often the prettier the pot, the fewer holes it has. If it is a workable material, enlarge or drill more holes; if it is not workable, then don't use it! The container should be held just off the ground. If it sits flush, the drainage holes can get blocked, and the plant suffers.

You should not put gravel into the bottom of the pot - it is a myth that this helps drainage.

Container size

Clematis have large, greedy roots that need some room. Smaller varieties will survive in a small pot, but flowering will be poor, and they will become disease prone over time.A minimum-sized container will be at least 15 inches (40cm) wide and 18" (45cm) deep at their smallest dimension: if the pot is narrower at the base than the top, then you measure the width at the base.

Compost matters

Peat-based composts are not recommended for Clematis. They are hard to wetten once dry and have virtually no nutrient content. Don't use garden soil either: it generally performs badly in pots, and doesn't hold water well.

There really is no substitute for soil-based John Innes Multipurpose compost. It is easy to water, has excellent drainage and contains all the necessary slow-release nutrients for good health and vigour.

Supporting Container-Grown Clematis

This may require some trial and error! Clematis carry a considerable amount of foliage. If the support is not strong enough and well anchored, it can break in the wind and damage your plant.

Sticks inside the container tend not to be a good idea as they wave in the breeze, disturbing the roots by causing wind rock; firmly fixing supports to the outside of the pot is harder, but a much better option. The best solutions are really the same as for clematis in the ground: a sunny wall or fence to train them over or a shrub or tree that casts dappled shade to scramble through.

Aftercare for container-grown Clematis

Consistent watering through the growing season is vital: a clematis that dries out may never forgive you! Do not water every day: two or three times a week is enough in the hottest, driest summers.

You can feed your clematis while watering. Every fortnight, use a liquid feed (root and foliar) such as Neudorff Rose feed which contains similar parts of nitrogen (N) and potash (K). All fertilisers list their makeup on the label: use any with close to equal parts of N and K. Start feeding as the plant breaks into growth and stops as soon as you see a flower bud. Do not feed again until flowering has stopped: if flowering continues into early autumn, that means don't feed until the following spring. Too much feed late in the season encourages soft growth, which will be killed by frost.

How to Prune Clematis - Overview

All clematis will need at least some pruning to some extent after their first prune at planting time. Excluding herbaceous clematis (which we don't sell), there are three pruning groups.

Remember that all Clematis, regardless of pruning group, benefit from a first pruning after planting.

Pruning Group 1 (or A) Clematis

This includes the Clematis species alpina (such Pink Flamingo), armandii, cirrhosa, macropetala and montana. They only flower on wood made the previous year.

Pruning Group 2 (or B) Clematis

These are the early large-flowered forms that do most of their flowering in May and early June on stems made in the previous year, and then often give you some more flowers before winter. Think of them as half and half: some of the wood needed for this year's earlier flowers was produced late last year, and some grows early this year for the later display.The blooms are often double for the first flowering, and single when they flower again later in the season.

The most famous member of this group is Nelly Moser, and it includes the likes of Lasurstern, Vyvyan Pennell, Mrs Cholmondeley and Duchess of Edinburgh.

Pruning Group 3 (or C) Clematis

Pretty much all the rest. They flower on the current year's growth. It is a diverse group, including the species Clematis orientalis, texensis, tangutica, and smaller viticellas as well as the late, large-flowered hybrids like Gipsy Queen.

How to Prune Group 1 Clematis

The easiest to prune. These tend to be larger plants, and they all bloom early.

There can be no flowers without buds, and their early flowering means their flower buds were created the year before: they only flower on the wood of the previous year. If you pruned them when they were dormant (i.e. the "normal" time for most woody plants), you would remove the following year's flower buds and your group 1 clematis would be forever flowerless!

The general rule with Group 1 clematis is to prune as little as possible. You can trim them lightly immediately after flowering to tidy, and to prevent them from putting energy into developing seeds, which encourages more new growth that will carry the flower buds for the following year.

If, and only if, a Group 1 clematis outgrows its allotted space, then cut out the offending shoots immediately after flowering (generally in May).

It bears repeating: the golden rule is "prune immediately after flowering, and only if you really have to". These clematis really do not like severe pruning. If possible, try to phase structural reductions over a period of 2-3 years, as a drastic prune in one go can kill your precious old clematis. A partial exception to that last point are the Montana Clematis, which can handle some pruning to keep them at the size you want them.

How to Prune Group 2 Clematis

Nearly as easy as Group 1, Group 2 Clematis will produce their first flush in May or early June.

In February or early March (maybe mid-March if the winter was very cold), their buds will be swelling, green and easy to see. This is the time to tidy up the plant gently:

• Start at the top of a vine and work downwards.

• Once you reach the first pair of good, strong, chubby buds, prune just above them.

• Repeat for the rest of the plant.

Again, be gentle. Less is generally better than more, and as with group 1, you should only ever be heavy-handed when the plant is too large or has a main growth where you don't want one.

How to prune Group 3 Clematis (Traditional)

Compared to the other two, pruning Group 3 clematis is brutal. Be brave: prune early, prune very hard, and leave (almost) nothing standing! The key is that these plants all flower on the new season's growth, so the old must be removed.

Prune Group 3 in February in the South, and early March in the North. The process is almost the opposite of pruning Group 2 plants:

• Start at the base of a vine and work upwards.

• Once you reach the first pair of good, strong, chubby buds, prune just above them.

• Repeat for the rest of the plant.

You will remove the vast majority of the plant. If you do not do this, the base of the plant develops a rather ugly, leafless, leggy appearance, and you will get fewer flowers.

But wait, there is something else to try here:

Pruning Group 3 Clematis (The Christo Cut)

The method above is the textbook way and is best for new plants that are still settling in. The late Christopher Lloyd (1921-2006), who was a great clematis man and wrote one of the definitive works on the subject, walked me around his garden at Great Dixter in 1988 or '89. He was charming, very funny, and tended to think outside the box.

He hated the way mature, well-established Group 3 clematis looked after they had finished flowering - all knackered out. He followed the rules above, except that he pruned these older specimens in November to save looking at them over winter.

In a fierce winter, the new growth in February would be cut back by frost, but no matter: new growth races up, and profuse flowering happens as normal. Try this, and your garden will look tidier. The deal is that you recall one of the truly great gardeners when you do so.