How to grow perennial plants

What are perennials?

Perennial plants live for many years and come in all shapes and sizes. These versatile and diverse plants fill our gardens with colourful flowers and ornamental foliage and are the mainstay of most borders. Many are hardy and can survive outdoors all year round, while less hardy types need protection over winter.

In a gardening context, the term

Perennials are plants that live for multiple years. They come in all shapes and sizes and fill our gardens with colourful flowers and ornamental foliage. Many are hardy and can survive outdoors all year round, while less hardy types need protection over winter. The term herbaceous perennial is used to describe long-lived plants without a permanent woody structure (they die back to ground level each autumn), distinguishing them from trees, shrubs and sub-shrubs.

Perennials are plants that live for multiple years. They come in all shapes and sizes and fill our gardens with colourful flowers and ornamental foliage. Many are hardy and can survive outdoors all year round, while less hardy types need protection over winter. The term herbaceous perennial is used to describe long-lived plants without a permanent woody structure (they die back to ground level each autumn), distinguishing them from trees, shrubs and sub-shrubs.

perennials

There are two main types:

• Herbaceous perennials – these die back to the ground in late autumn. The roots survive over winter and the plants re-sprout every spring. Examples include delphiniums, hardy geraniums and hostas.
• Evergreen and semi-evergreen perennials – these keep their leaves for most, or all, of the year. Examples include bergenias, epimediums and hellebores.

Choosing the right perennials

Getting the right look

Consider what you want from your perennials when you consider buying them. For instance, do you want to colour-theme your border, or create an exciting mix of contrasts? Or to reate a naturalistic or exotic planting scheme? Here are some pointers to help you choose:

• Flower colours – you can choose flowers in every imaginable hue, from gentle pastels to vivid, exotic shades.
• ​Foliage - is available in wide ranging forms and colours to provide interest throughout the growing season. Foliage can often last much longer than flowers, so its colour and form is an important consideration when selecting a plant

• Season of interest – there are perennials for every season, although the majority flower in spring or summer. To keep your garden full of interest all year, include some that flower in autumn and winter too.

• Style – do you prefer the natural look of

  A native plant is one that originated or arrived naturally in a particular place without human involvement. In the British Isles, native plants are those that were here during the last ice age or have arrived unaided since.

  native wildflowers, such as primroses and ox-eye daisies, or something more exotic, such as red-hot pokers and arum lilies?

• Size – perennials come in all sizes, from low ground cover to towering spires, and everything in between. Keep your borders interesting by including a range of heights.

• Shape – you can choose from low horizontal ground cover to tall verticals, or neat compact clumps to vigorous spreaders that will fill gaps quickly.

• Evergreen or herbaceous – do you want foliage all year round (evergreen) or plants that die down in late autumn and sprout afresh every spring (herbaceous)? A mix of both will keep borders interesting across the season. For ground cover, evergreens are best as their year-round mat of foliage deters weeds.

• Wildlife-friendliness – many perennials attract wildlife, providing nectar-rich flowers, seeds for birds, and shelter for small creatures.

Perennial borders: choosing plants

Perennial borders: choosing plants

Ten classic summer perennials

Ten classic summer perennials

How and what to buy

Dormancy refers to a period of inactivity in plants, during which they slow down or stop their growth, conserving energy and resources. This is a natural process that helps them survive harsh conditions, such as winter or drought. Dormancy in seeds is a mechanism that prevents them germinating until environmental conditions are favourable for growth.

dormant

These have been lifted from the ground while dormant, with little or no soil around their roots. Various plants may be available bare root, including fruit trees, hedging plants and some perennials. They are generally cheaper than plants in containers, but are only available in winter/early spring, while dormant

bare-root

Where to get ideas and advice

To explore and narrow down your potential planting choices, you can: 

• Visit gardens with lots of perennials, such as the RHS Gardens, where all the plants are labelled, so you can note down your favourites.

• Ask at nearby garden centres, which should offer a range of perennials that do well in your local conditions. 

• Browse our perennial plant profiles for photographs and plant descriptions. You can also refine your search by specifying growing conditions, flower colour, season of interest, and more.

• Visit a specialist nursery, in person or online.

When to plant

• Good-sized hardy perennials are best planted outside in autumn or spring. 
• Bare-root plants, young plants and plug plants are usually only available in spring, and are best potted up straight away into containers.

Where to plant

Shade planting: annuals, bulbs and perennials

Shade planting: annuals, bulbs and perennials

Prepare your soil

Weed the area thoroughly before planting – if weeds are left, they can spread in among your perennials, which makes them trickier to remove.

How to identify common weeds

How to identify common weeds

How to plant

You can also plant perennials in containers, either singly or with other plants. It’s simple and takes little time – see our guide to planting up containers.

Bare-root plants, young plants and plug plants are best planted into containers initially, until they are larger and growing strongly. They should be ready to plant into borders after a few months.

Watering

How to water wisely

How to water wisely

Feeding 

Most perennials in borders need no additional feeding, but if the soil is particularly poor, you could add a well-balanced fertiliser, such as Growmore or blood, fish and bone, in spring.

Fertilisers

Fertilisers

Weeding

It’s best to weed between perennial plants regularly, so weeds can’t get established or scatter their seeds. Mulching the border with garden compost in spring will help to deter the germination of annual weeds. 

How to identify common weeds

How to identify common weeds

Staking

Winter protection

Ten of the hardiest hardy perennials

Ten of the hardiest hardy perennials

Perennials in containers

Caring for older plants

Perennials need little pruning. However, there are two instances where it is needed:

• Cutting back – herbaceous perennials die back in late autumn and the dead stems should be cut off at the base before new shoots appear in spring. If you leave them in place over winter, some may look a little untidy, but will provide valuable shelter for overwintering beneficial insects

• Chelsea chop – perennials that are liable to flop can be reduced in height in late May to produce stockier plants or delay flowering

Perennials are easy to propagate in several ways:

• by dividing the clump
• by taking cuttings – either softwood or semi-ripe, or root cuttings
• by growing from seed, either bought or saved from your plants 

Perennials, especially hardy ones, are usually robust and trouble free. However, look out for the following problems:

• Nibbled young shoots and holey leaves may be caused by slugs, snails, rabbits and mice.
• Yellow leaves (chlorosis) may be a sign of nutrient deficiency.
• Tall or top-heavy flower stems may flop over or break – put supports in place in spring.
• Plants may occasionally go into decline for no apparent reason – this often starts with browning leaves and may be caused by a disease such as phytophthora or pythium root rot.