How To Grow Clematis / RHS Gardening

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:

1. Winter and spring-flowering
2. 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)
3. 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 choosing healthy plants

RHS Guide to choosing healthy plants

RHS Guide to buying mail order plants

RHS Guide to buying mail order plants