How to grow garden euphorbias

What are euphorbias?

Euphorbia is a very large genus which includes houseplants, but the ones featured here all make great garden plants. They provide vibrant acid-yellow or orange flowerheads, and bold green or greyish-blue leaves. There are plants for sun and shade, wet or dry conditions, so these euphorbia are worth exploring as you’ll often find that there is one that we grow happily in most positions in a UK garden. However, not all are hardy, so if you live in a cold area, it’s worth checking the description first and assessing the microclimate your garden offers.

Microclimates: assessing your garden

Choosing the right euphorbias

The main criteria for selecting euphorbias are growing conditions and plant size. In relation to colour, most euphorbias are green with lime or acid yellow flowers from early spring or in early to mid summer, but there are a few choices you could make with burgundy foliage (Euphorbia amygdaloides 'Purpurea' ), blue foliage (E. rigidaandE. charcias subsp. wulfenii) or even variegated

Variegated means having leaves or other plant parts with streaks, blotches or patches of different colours. Typically, these would be a combination of two colours, such as green and gold or green and white.

foliage (including E. characias 'Tasmanian Tiger').

Eventual size

Habits and size vary, so check the plant label before you buy. They range from plants about 10cm (4in) tall suitable for the front of borders to those more than 1.8m (6ft) tall to go at the back.

Growing conditions

Think about whether you can offer a sunny or shady spot, as well as how well the soil drains, when you’re choosing what euphorbia to plant where. There’s a euphorbia for most positions in the garden, and here are some examples:

• For a sunny border and suitable for most garden soils that aren't waterlogged
  

  Describes soil or potting compost that is saturated with water. The water displaces air from the spaces between soil particles and plant roots can literally drown, unless they are adapted to growing in waterlogged conditions. Waterlogging is common on poorly drained soil or when heavy soil is compacted.

  : Euphorbia schillingii, E. cornigeraand E. donii 'Amjillasa'
• For sandy, free draining soils and sunny conditions: Euphorbia. 'Abbey Dore', E. characias subsp wulfenii 'Jimmy Platt' and E. rigida. These are often the blue and silvery leaved
• For moist or shady conditions: E. amygdaloides var. robbiae for dry shade or E. palustrisand E. grifithii 'Dixter' for damp soils
• In need of shelter from cold in winter (such as in a sunny city garden) and good drainage: E. mellifera

To browse photos and descriptions of euphorbias, go to RHS Find a Plant. You can search by flower colour, height, growing conditions, RHS Award of Garden Merit and more, to help narrow down your choices.

Soil types

Buying euphorbias

Euphorbias are widely available in garden centres and nurseries, and from online suppliers, with a larger choice available by mail order from specialist plant nurseries.

They are mainly sold as plants in spring or larger plants in flower in summer and early autumn. Most are in 1 litre or 2 litre pots, but occasionally you will see smaller plants in 9cm (3½in).

Where to plant

Check the plant label for growing conditions and for eventual size to indicate spacing, as this varies greatly, depending on what you choose to plant. You can also browse photos and descriptions of euphorbias in the RHS Find a Plant.

When to plant

In most areas of the UK, it is best to plant in spring as the moist soil and warmer weather helps plants establish quickly. This is epecailly true of the blue and silvery leaved types, which struggle through winter on moist soils, so are best not planted in autumn and winter.

How to plant

In the ground

Plant euphorbias as you would any border perennial

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.

. This is simple and usually involved digging a hole wider than the rootball

The roots and accompanying soil when a plant is removed from a container or lifted from the ground.

of the new plant, placing it in the hole, and backfilling with soil that has been improved with organic matter such as well-rotted garden compost

Can refer to either home-made garden compost or seed/potting compost:

• Garden compost is a soil improver made from decomposed plant waste, usually in a compost bin or heap. It is added to soil to improve its fertility, structure and water-holding capacity. Seed or potting composts are used for growing seedlings or plants in containers - a wide range of commercially produced peat-free composts are available, made from a mix of various ingredients, such as loam, composted bark, coir and sand, although you can mix your own.

or manure. In the case of plants that like dry conditions, such as E. myrsinites, the organic matter isn’t required. All require watering in well, and keeping moist until they establish.

In containers

Most euphorbias prefer growing in the ground, but some such as E. myrsinites, can do well in containers. This is mainly because they like free draining soil, and it’s very easy to mix up a potting compost that provides these conditions exactly. Mix 3 parts peat-free John Innes No. 3 compost with one part grit.

Perennials: planting

Watering

Water well during dry spells, to establish plants in the ground in their first two growing seasons. Plants in containers need watering from spring to autumn to prevent the compost

Can refer to either home-made garden compost or seed/potting compost:

• Garden compost is a soil improver made from decomposed plant waste, usually in a compost bin or heap. It is added to soil to improve its fertility, structure and water-holding capacity. Seed or potting composts are used for growing seedlings or plants in containers - a wide range of commercially produced peat-free composts are available, made from a mix of various ingredients, such as loam, composted bark, coir and sand, although you can mix your own.

drying out completely; the aim is to keep the compost just damp.

Watering

Feeding

Euphorbias rarely need feeding. They often become lush and leggy if the soil is rich or they are fed too much.

Deadheading

You’ll find some euphorbias with a permanent framework of branches will need deadheading

Deadheading is the process of removing spent flowers from plants to encourage more blooms and prevent seed production. This helps to redirect the plant's energy into producing more flowers rather than producing seeds.

after flowering or, if the entire flowered stems starts to die back, selectively cut these out at the base. You’ll be left with a good dome of short unflowered stems/shoots, which which will develop flowers the following year. Examples include E. characias subsp wulfenii and E. myrsinites.

The evergreen groundcover of E. amygdaloides var. robbiae can be deadheaded by shearing off spend flower stalks in summer to tidy up clumps.

Mulching

It’s always a good idea to mulch borders to keep down weeds and stop water evaporating. This may be with organic matter, preferably homemade compost, for normal garden growing conditions, or with gravel if growing the silvery and grey species in a Mediterranean-style planting scheme.

Pruning is usually carried out when you deadhead, so see our section on Deadheading

Deadheading is the process of removing spent flowers from plants to encourage more blooms and prevent seed production. This helps to redirect the plant's energy into producing more flowers rather than producing seeds.

in Ongoing Care above. However, herbaceous plants will die back for winter, so old, brown and dead-looking stems can be cut off to tidy up the plant.

Clump-forming (herbaceous) euphorbias

These are propagated by division. This will in late spring for the earliest flowering, as you will carry this out straight after flowering. For anything that blooms later in summer, the best time to divide is in spring as plants come into growth.

Shrubby euphorbias

Shrubby euphorbias, including those that produce stems one year that flower in the next year, are propagated by softwood cuttings. Use the short shoots at the base in early spring. Ideal candidates include: E. characias and its relatives,E. myrsinitesand E. mellifera.

Growing from seed

Species can be grown from seed, but cultivars will not come true and the seedlings

A seedling is a young plant grown from seed.

will be slightly different habits and colours. Collect seed when capsules turn brown.

Annuals

Annuals are plants that complete their life cycle in one growing season. They are generally easy to grow from seed or can be bought as young plants from garden centres. Annuals are ideal for growing in summer containers and filling gaps in borders. Some examples of annuals include sunflowers, cosmos, sweet peas and zinnia.

like E. marginata can be sown in spring.

Cuttings: softwood

Euphorbias are generally trouble-free but can suffer from:

• Powdery mildews on the leaves and flowers
• Aphids causing distortion to leaves and stems
• Root rots if grown in wet soils
• Rust diseases can occasionally be a problem

Some species such as E. amygdaloides var. robbiae (wood spurge) and E. cyparissias (Cypress spurge) spread widely by rhizomes

Rhizomes are creeping swollen root-like structures that are actually adapted stems. Roots, stems with leaves and flowers are produced along its length. See plants such as Anemone nemorosa, bamboo, canna, border iris.

and may become invasive

Invasive plants are those that grow vigorously, spread rapidly and can out-compete other plants. Native, non-native and cultivated plants can all be invasive.

. Dig out the excess each spring to prevent them spreading too much.

If you’re a member of the RHS, you can use our online Gardening Advice Service, via MyRHS, for any gardening queries and problems or subscribe to the RHS Grow app.

Toxicity

All parts of euphorbia plants may cause severe discomfort if ingested, and the contact with the sap

Sap is a fluid that circulates through a plant's vascular system, in a similar way to blood moving through our veins. Phloem sap carries the sugars produced in the leaves by photosynthesis down to roots and other storage organs, as well as carrying minerals and hormones. Xylem sap is watery and transports nutrients absorbed by the roots upwards to the rest of the plant. Some plants leak sap from wounds or pruning cuts, and this is known as bleeding.

may irritate the skin or eyes. Wear gloves and other protective equipment when handling, especially when pruning