How to Grow Clematis

Hardening off

When purchasing a clematis in early spring, the soft growth must be hardened off before planting. To do this - stand the plant outside in a sheltered position during the day but take it in under unheated cover overnight. Ensure the compost in the pot is kept moist but not too wet. Continue for about two weeks before planting.

Planting

Water the clematis thoroughly before planting.
If you are planting by a wall or fence the hole should be dug approx. 12" (30cm) away from its base.
If you are planting by a tree or shrub - try to plant on the north side, the host will then shade the root system of the clematis. Plant about 2' (60 cm) away from the trunk of a tree leaning the supporting cane towards the trunk. If you are planting the clematis to clamber over a shrub, dig the planting hole just outside the 'drip-line' - this is outside the outer branches.
Whatever your soil type, whether it is heavy or light, acid or alkaline, it should be improved before planting.

Method

1. Fork the soil through thoroughly, and as deeply as possible and incorporate some compost, either garden or bagged, which will help to improve the growing conditions.

2. Dig the hole much bigger and deeper than the size of the flower pot, deep enough to ensure the lowest leaf joints will be buried beneath the surface of the soil once planting is completed.

3. Break up the soil in the bottom of the planting hole.

4. If you are using manure, put a layer in the bottom of the hole and cover it with at least 2" of soil.

5. Sprinkle one good single handful of bonemeal into the hole and mix it into the loosened soil.

6. Remove the ties from the base of the plant, which will eventually be covered with soil.

7. Remove the pot - Please handle the plant carefully to avoid damaging the stems of the clematis. Now loosen the roots if they are in a tight ball. This is essential to encourage good rooting. Even breaking some of the roots may be necessary but this will aid the development of new root growth. Please note, we use slow release fertiliser and this is found as small yellow or orange beads in the compost. They are NOT eggs and should NOT be removed.

8. Place the plant carefully in the hole and re-fill it with soil, firming down by hand.

9. Water the plant in thoroughly - and keep it watered during very dry spells especially if your soil is light and very free draining. A large can of water once or twice a week is better than a cup full every day! A clematis planted by a wall, fence, tree or shrub, may need regular watering.

10. If your clematis is planted in a hot, sunny position where the base of the plant will be baked for a large part of the day, place some stones, bark chippings or similar around the base to provide shade for the root system. This will help to keep the roots cool and moist. Water regularly.

Growing Clematis in Containers

Choose a large container, preferably terracotta not plastic, at least 18" deep with adequate drainage holes. Put plenty of crocks, stones or gravel in the bottom and stand the container on feet or bricks to ensure good drainage.

Unless you mix your own compost we would recommend using John Innes No.3 mixed with a quarter as much again of peat or peat substitute. Plant the clematis as described for the open ground.

Check regularly for watering needs - Do NOT keep container-grown clematis too wet over the winter, and ensure the pot is draining freely!

From late spring to early autumn we recommend using liquid tomato feed - see Feeding.
At pruning time remove an inch or two of compost from the top of the pot and replace with fresh compost to which a single handful of bonemeal has been added, and water it in. Every four to five years root-pruning may be necessary. At pruning time, when the plant is dormant, cut away 2"-3" of root from the outside of the rootball. Cut one third off the bottom, and re-pot the plant.

Patio Clematis - specific notes.

To keep these clematis compact, we recommend HARD pruning in February / March and pruning hard again after the first flush of flowers has finished.
In other words - ignore the 'normal' pruning instructions!

Pruning - New Clematis

We strongly recommend that you hard prune all clematis at some time within the first year of planting. This will encourage your clematis to put its roots out and form a strong root system. It will also encourage new shoots to 'break' from the leaf axils below soil level, from the leaf axils, which were buried when the clematis was planted. The more stems you have on your clematis, the more flowers you will have!

For Tidy (Group 1) this hard-prune should be carried out immediately the first year's flowering has finished.

For Light (Group 2) this hard-prune should be carried out during late winter or early spring (February / March) the first year after planting.

For Hard (Group 3) these will be hard-pruned every February / March.

Method - Prune all growth back to just above a good set of viable buds in the leaf joints approximately 6" to 9" above the ground.
Alternatively all clematis can be hard-pruned when planted. Thereafter simply follow the pruning method for established clematis.

Pruning Established Clematis

Tidy - (Group 1) (armandii, atragenes, cirrhosa, montanas, etc.)
Following the initial hard-prune, these cultivars simply need a good 'tidy up' each year immediately flowering has finished.
This consists of pruning off unwanted growth then tying the remainder to its support. If you wish to keep them more compact, hard-prune immediately after flowering. This will prevent the montanas from getting out of control and will stop others from getting a woody structure at the base. This can really only be done successfully in milder climates where the clematis will be able to make sufficient growth after pruning to re-establish the growth and ripen the wood to flower the following year. If you try this and your clematis fails to bloom well, simply avoid hard-pruning and allow the stems to ripen, you should find that flowering will improve.

Light - (Group 2) (Early Large Flowered Cultivars)
Following the initial hard-prune, light-pruning should be carried out during late winter or early spring (February / March) each year.
Start at the top of the plant and reduce all stems down to a good set of viable buds in the leaf joints, then cut out any dead or weak growth and tidy the remainder of the plant to a good shape. Also at this stage consider hard-pruning just two or three stems to encourage young growth from soil level. This will help to keep the plant flowering low down and generally look much better.
A complete hard-prune every few years will help to rejuvenate an old, tired plant. When you are carrying this out we would recommend partially pruning the clematis to between thigh and waist height during late autumn or early winter and tying in the remaining stems to avoid wind damage over the winter period. This partial pruning will encourage viable buds to form in the leaf joints low down on the stems which will then make the final hard-pruning in late winter / early spring more successful (for method see below).

Hard - (Group 3) (Late Large Flowered Cultivars and viticella, texensis, herbaceous cultivars, species, etc.)
Hard pruning is normally carried out during late winter or early spring (February / March). Prune all growth back to a good set of viable buds in the leaf joints, approximately 6"-18" from soil level.

If you prefer to tidy your clematis in late autumn or early winter, partial hard pruning can be carried out then. Roughly prune to 18" and tie the remaining stems to prevent damage in a windy situation. Then in late winter or early spring a full hard-prune can be carried out. It is always safer to leave a bit of extra growth on the clematis over the winter period and not prune too hard too soon.

Do not hard-prune the herbaceous heracleifolias until mid-spring (April) when the weather has improved as they over-winter much better with their old growth left intact.

Completely dead stems on some herbaceous cultivars, such as the integrifolias, can be cut almost to soil level in late winter or early spring, simply avoid nipping off the new shoots as they are emerging from the ground!

Optional Pruning (Light OR Hard)

Following the initial hard prune you can choose to either light or hard-prune these cultivars. Hard-pruning will delay the flowering period by approximately 6 - 8 weeks, but will keep the plant more compact.
Occasionally with hard-pruning, one or two varieties will refuse to bloom, in which case lightly-prune them the following year and you should find them flowering better. Applying liquid tomato feed will encourage better flowering - see 'Feeding'.

DEAD- HEADING - Early large flowering clematis from light-prune (Group 2) benefit from dead-heading after the early flowers have finished. Then apply liquid tomato feed as recommended in 'Feeding', which will encourage new flowering wood to form and another good display of blooms can be enjoyed in late summer and early autumn.

Clematis Pruning Demonstrations

If you are able to travel to the nursery, you may be interested in attending a pruning demonstration. These are held in February, for further information, click here Pruning Demonstrations.

Feeding

Apply a good single handful of bonemeal when pruning has been carried out. This should be worked into the soil around the base of the plant and watered in.

During mid spring (April) a single handful of Sulphate of Potash can be applied (as with bonemeal),
OR from late spring (May) use liquid tomato feed (Tomorite or Tomato Maxicrop) once a fortnight until early autumn (September). Tomato feed is high in potash and that, or Sulphate of Potash will improve the colour, size and quantity of your clematis blooms. Use either one, or the other, NOT both.

Clematis benefit greatly from an annual mulch of manure or good garden compost during the autumn. However, don't put manure too close to the stems of the plant.

Pest Control

We use natural predators for biological control of common pests to reduce the use of chemicals on our nursery. If you notice a few 'bugs' on your plants, they may be friends, not foes!

Slugs & Snails - The damage inflicted on clematis by these common garden pests can be devastating and the plant may appear to 'Wilt'. The control of slugs and snails is essential to successful clematis growing so use whatever preventative methods you prefer. Animal-friendly slug pellets are now available, please check with your garden centre before purchase, or use a biological control, in the form of nematodes, available from www.greengardener.co.uk.

Clematis Wilt

If your clematis suffers from wilt, it must be cut down to just above the first set of leaf joints from the ground, this will encourage fresh growth to shoot from below soil level. The soil surrounding the roots must then be drenched with fungicide - we recommend using general systemic fungicide. Drench twice, 1-2 weeks apart.

Many clematis are NOT prone to 'wilt', if you are at all concerned about the problem please try growing the species or viticella cultivars which are not susceptible. Damage to the stems by slugs and snails will also cause clematis 'wilt' - take appropriate action to get rid of these pests.

Hot Climates

We have many customers who garden in countries with warmer climates like in southern France or even hotter such as South Africa or southern Japan. We are grateful to them for giving us feedback on what does well and what does not in these hotter climatic conditions.
Generally we would suggest the following as a guide to those types that are happier in a warmer climate. However, all individual environments do differ, so we cannot guarantee success in any particular location.

Keeping the clematis moist at the root is key. Ensure that the compost does not dry out, nor become waterlogged from too frequent watering, then most clematis will cope with reasonably high summer temperatures.
Growing them in pots or containers of some sort is often a better way to ensure good soil and moist, yet free-draining conditions. We understand, for example, that the local soil in Madeira and parts of South Africa is not ideal. There is really no need to shade the roots - although it can help to retain moisture, it can also harbour slugs and other pests.
Most general advice is still the same as in England; Water the plants daily; feed them every two weeks even when they are flowering, and keep pale coloured types that are prone to fading, in shade. (Guidance on Aspect is given in our catalogues - both printed and online).

As a guide, based on feedback from customers, you may like to try the following -
Most of the species, such as terniflora, serratifolia, viticella and heracleifolia.
Cirrhosa and other evergreens, but they may exhibit summer dormancy, losing their leaves in the hottest months.
The Tangutica Group will be fine in drier soils but high humidity may be a problem.
Montanas generally, although they do need a good supply of water especially as they can become very large.
Most large flowered types, but treat all as hard-prune (Group 3), ignoring UK guidance, to avoid too much dead foliage after the early flowers. They should flower again 6 - 8 weeks later.
The Integrifolia Group and Texensis Groups, but these must be kept moist at the root to avoid mildew problems.

Those not suited are the Alpina Group, especially in hot, humid climates such as Japan.