How to grow clematis / RHS

All you need to know

Being one of the most popular garden plants, there are many different species and cultivars to choose from. To pick one that's right for your garden, consider the following:

Size and habit

Firstly consider if you want a climbing plant, perhaps for a wall, fence, pergola or obelisk, or are you looking for a non-climbing herbaceous clematis to grow in a mixed border?

Then consider the space you have available:

Most herbaceous clematis grow to between 75cm and 1.5m tall, with a spread of less than 1m
Climbing clematis range from very vigorous types, suited to covering a house wall or growing into a mature tree, to small and compact ones, suited to container-growing. The vast majority reach around 3m high

Planting position

Most clematis grow best in a sunny or part-shaded position, but there are plants available to suit any aspect. Consider the conditions in your garden and choose a plant that will thrive there, whether that’s a shady wall or a particularly hot and sunny one.

If you want an evergreen clematis, bear in mind that these need a sunny, sheltered spot.

Flowers

Clematis are grown for their flowers, so it makes sense to choose one that appeals to you most and works well with the rest of your garden:

Do you want large, showy flowers, perhaps striped or double, or something more subtle and delicate?
What colour would you prefer?
Would you like scented flowers or decorative seedheads after flowering?

Consider if you would like your plant to flower at a particular time of year? Most herbaceous clematis flower during the summer, while climbing clematis are roughly divided into three groups:

Winter and spring-flowering
Early-summer-flowering (also known as twice-flowering as many produce a flush of flowers in late spring/early summer and another in late summer)
Late summer and autumn-flowering

Some bloom over a long period, while others produce one big flush of flowers.

To help you decide

You could:

Visit a garden known for its clematis display, like Sissinghurst, West Dean or RHS Garden Hyde Hall, or visit a local garden centre – seeing plants in flower allows you to compare colour, size and fragrance easily
Visit a clematis specialist, either at an RHS flower show or at their nursery
Visit a National Collection holder – in the UK there are collections of Clematis montana and C. viticella
Get more information from the British Clematis Society or International Clematis Society
Read the RHS Clematis alpina & C. macropetalum trials bulletin

Buying a clematis

Clematis are widely sold in garden centres and available mail order from many nurseries, including a number that specialise in these plants. Use our Find a Plant tool to find stockists.

Popular species and cultivars are often available year-round, while more unusual types may only be available at certain times of year. In garden centres, this is often just before flowering, when plants are in bud.

Clematis are usually sold as container-grown plants, with climbing types grown up a tripod of canes or small trellis for support.

Consider the following when choosing a plant:

Well-developed plants with more than one stem growing from the base and growth that covers most of its support, will get going and flowering more quickly
Roots should be developed enough to be visible through the holes in the base of the pot
Avoid plants showing signs of stress, damage or disease
Take care transporting your plant home, as clematis have quite fragile stems

RHS Guide to buying mail order plants

RHS Guide to choosing healthy plants

When to plant

The best time to plant clematis is in spring or early- to mid-autumn, as warm, moist soil at these times of year aids good root establishment
If you buy a container-grown plant during the summer, plant it as soon as possible and water it regularly
You can plant clematis at other times, but avoid planting in waterlogged or frozen soil and during periods of drought

Where to plant

Bear the following in mind when choosing a site for your plant:

Most clematis will grow well in sun or partial shade, but flowering is normally disappointing in a very shady spot. Herbaceous types need a full sun position
Some, including winter and spring-flowering evergreen types, need a sheltered spot as they are not as hardy
Climbing clematis need their roots to be kept cool and moist, so plant the base of these clematis in light shade or provide shading with other plants or a dressing of pebbles
Allow enough space for your plant to grow into – some clematis are vigorous climbers and will quickly become a nuisance in too small a space
Consider how you will support your plant’s stems. Herbaceous clematis are best grown through plant supports or into nearby shrubs, while climbing types will need something to twine around, like trellis or mesh attached to a wall or fence

How to plant

Prepare your soil

Clematis are tolerant of a range of soil types, but grow best in deep, fertile, moist but well-drained soil. On heavy or sandy soils, dig-in some organic matter, like leaf mould or well-rotted manure, before planting to improve soil structure.

Planting

Plant large-flowered hybrid cultivars (early and late-summer-flowering) with the top of the rootball 5-7.5cm (2-3in) below the soil surface. This encourages new shoots to grow from below ground level and also helps the plant recover if affected by clematis wilt
Plant winter and spring-flowering clematis (including evergreens), late-summer and autumn-flowering species clematis and their cultivars, like Clematis viticella and C. tangutica, as well as herbaceous clematis, with the top of the rootball just below the soil surface
If planting against a wall or fence, dig the planting hole so that the rootball will sit around 30-45cm (1ft-18in) from its base, and further out if there is guttering or an overhanging roof. Use a bamboo cane, if necessary, to help the plant reach its permanent support

Growing clematis into trees and shrubs

There are a few extra things to consider when planting a clematis to climb into a tree or large shrub:

Plant the clematis on the windward side of the tree or shrub so that as it grows, and its stems extend, they are blown onto the trunk or into the branches, where they can obtain a hold
Position the clematis at least 1.2m (4ft) away from the base of the tree or shrub to reduce competition for light, water and nutrients. This is particularly important if growing into a tree with a dense root system, like a beech or cherry, or into a conifer
Use a bamboo cane or wires to help the clematis reach the trunk or branches, if necessary
Avoid using clematis to cover dead trees or tree stumps as they can soon become hosts to diseases, particularly honey fungus

Growing clematis in containers

Smaller-growing clematis make attractive container plants, especially when trained up an obelisk or small trellis.

To grow clematis this way:

Choose a pot at least 45cm (18in) deep and wide, and use a soil-based potting compost such as John Innes No. 2
Remember clematis in containers still need their roots kept cool, so top-dress the pot with a layer of pebbles, plant low-growing plants like summer bedding in the same container, or position other planted containers on the sunward side
Try not to position container-grown clematis right up against the base of a wall or fence, especially where there is guttering or an overhanging roof, as it can be very dry. Instead position around 30cm (1ft) away, or site in a more open spot

RHS Guide to planting up containers

Watering

Clematis are thirsty plants, disliking soils that dry out during the growing season, when they can be prone to drought stress.

To keep your plant growing happily:

Water newly-planted clematis regularly during periods of dry weather in the first few seasons after planting. Once established, plants shouldn’t need regular watering, unless growing on a very free-draining soil or during prolonged hot, dry spells
As soil in containers dries out more quickly, container-grown clematis need particular attention. Water these most days between April and October, keeping an eye on moisture levels during dry spells at other times of the year, for as long as they stay in the pot
Water thoroughly to soak the soil to around 30cm (1ft) deep, which for clematis in the ground, may require at least the equivalent of four watering cans per square metre

RHS Guide to watering

Feeding

Clematis will grow and flower better given some regular, additional feeding:

Feed those growing in the ground each year, in late winter or early spring. Apply a flower-encouraging potassium-rich fertiliser, like Vitax Q4 or rose fertiliser, around the base of the plant according to manufacturer’s instructions
Mulch immediately afterwards with organic matter, like well-rotted manure, leaf mould or garden compost, to improve the soil and help conserve moisture
Feed container-grown clematis monthly during the spring and summer using a general-purpose liquid fertiliser

RHS Guide to fertilisers

RHS Guide to mulching

Tying-in

It can seem unnecessary to tie-in climbing clematis, as they naturally twine very readily using their leaf petioles (stalks). However encouraging this process, and guiding stems so they spread out evenly over their support, improves flowering and helps prevent a tangled mass of foliage.

It may be necessary to tie stems in place with twine until they have secured themselves. Do this carefully, as clematis stems are fragile, using loose figure-of-eight knots (where the twine passes between the stem and support). Ideally don’t use plastic twist-ties, as these can cut into and damage stems.

Herbaceous clematis are non-climbing and many have sprawling, floppy stems. If growing these with plant supports, as opposed to letting them scramble through a nearby shrub, then these too will need tying-in.

RHS Guide to training climbers

RHS Guide to staking perennials

Container maintenance

Clematis in containers have a restricted root run and so need more regular care than those growing in the ground to stay happy and healthy. This includes top-dressing pots each spring, removing the top 5cm (2in) of old compost and replacing with a fresh layer. Our guide on container maintenance below gives more information.

RHS Guide to container maintenance

Regular pruning encourages strong, healthy growth, improves flowering and keeps clematis plants in check. Left unpruned, these climbers tend to form a mass of tangled stems with bare bases and flowers well above eye level, so although it can be a time-consuming task, it is well worth the effort.

Pruning newly-planted clematis

To encourage bushy plants with multiple stems, it’s a good idea to give all newly-planted climbing clematis an initial prune:

Cut back all stems to 15-30cm (6in-1ft) from ground level, cutting just above a bud
Prune autumn-planted clematis in the February or March after planting, and spring-planted clematis immediately after planting
Once new growth appears, pinch out young, developing shoots to a lower bud to promote further branching

Pruning established clematis

Clematis have a reputation for being difficult to prune, but they aren’t as long as you know when your plant flowers, as the three clematis pruning groups are based on flowering time:

Pruning group one – Clematis that flower in winter and spring on shoots produced the previous summer
Pruning group two – Large-flowered cultivars that flower in early summer (May and June), including those referred to as twice-flowering. These produce flowers on short shoots from last year’s growth, with a later flush on new growth
Pruning group three – Climbing clematis that flower from mid-summer (late June onwards) on new, current season growth, and herbaceous types

If you are unsure of which group your clematis falls into, observe the flowering time and follow this simple guide:

Flowering before early summer (June): do not prune
Flowering from late June onwards: prune in late winter (February)

Renovating overgrown clematis

Many clematis will tolerate hard pruning, to near ground level, if they have become overgrown or top-heavy. See the individual pruning groups above for more advice on the suitability of different clematis to renovation, as well as information on when and how to hard prune.

RHS Guide to pruning clematis

RHS Guide to renovating climbers

There are a few methods you can use to create new plants from your favourite clematis:

Clematis from cuttings

This is the most popular method of propagating clematis and allows you to create many identical copies of named cultivars.

Take double leaf-bud cuttings, which are similar in technique to semi-ripe cuttings, from healthy, non-flowering shoots between spring and late summer. Given warm, humid conditions, cuttings usually root within 6-8 weeks and will be ready for potting-up individually the following spring. Expect flowering within two years.

RHS Guide on taking cuttings from climbers

Layering

Serpentine layering, carried out between late winter and spring, is an easy method of propagating a small number of clematis plants and involves looping stems in and out of the soil to encourage the buried sections to root. It is particularly suited to those like Clematis montana and C. viticella, that naturally produce long, flexible stems.

It takes one to two years for buried stem sections to produce a good root system of their own. After this period, sever stems from the parent plant and pot-up or plant out, for flowers the following season.

RHS Guide to layering

Clematis from seed

Species clematis (i.e. not hybrids or named cultivars) can also be propagated from seed. Although a slower process than making new plants from cuttings or layering, it can be quite exciting, as seedlings will look at least slightly different from their parents and could have new or unusual flowers.

Ideally sow clematis seed fresh in the autumn, into pots of a gritty seed compost, and cover with a fine layer of compost and grit
Keep pots in a cold frame or unheated greenhouse over winter – this provides the period of chilling needed for good germination
Seedlings should germinate in spring. Prick out when large enough to handle and pot-up individually, firstly into 9cm (3½in) pots and then into 15cm (6in) or 2 litre pots when well-rooted
Grow on until well-established, providing support for climbing stems, before planting out
Plants may take over three years to flower

RHS Guide on growing clematis from seed

Please be aware that some clematis are protected by Plant Breeder’s Rights, and you are not allowed to propagate them for sale.

While we think all this information will be helpful to you, we always recommend to read the instruction labels on your plants.

How to grow clematis

Quick facts