Growing guide
How to grow astilbe
Lovers of rich, moist soil, astilbes surprise you with their sheer vibrancy and range of flower and foliage combinations. These hardy perennials are happiest in a shady spot, adding drama to bog gardens, damp borders and even containers.
Quick facts
- Hardy, easy-to-grow, robust perennial
- Must have damp soil, best in dappled shade
- Flowers from July to October
- Faded plumes look attractive through winter
- Range from 30cm (1ft) up to 120cm (4ft) tall
- Divide clumps every four years
- Ideal for bog gardens, natural pond edges and streamsides
All you need to know
What are astilbes?
Bold and colourful in both flower and foliage, astilbes add drama, vibrancy and texture, and are particularly impressive when planted en masse. They are hardy perennials, so live for many years, dying down in autumn and re-sprouting every spring.
The plume-like flowerheads come in shades of mauve, pink, red or white, standing tall above the foliage all summer long. They eventually fade to shades of buff and beige, providing interest into winter too.
The green leaves often turn rich yellow in autumn, while in spring the young leaves may have copper or bronze tones, especially the deep pink- and red-flowered cultivars.
Astilbes come from moist grassy habitats and lightly shaded, damp woods in eastern North America and East Asia. So in gardens, they like plenty of water and some shade during the hottest part of the day in summer. They work well with other moisture-lovers such as primulas, rheum, rodgersias and zantedeschias.
How to choose your astilbes
Once you know you have the right growing conditions for astilbes, decide how large you would like your plants to grow. Think about the scale of your planting area. You might like one large astilbe, for example, reaching 1.2–1.5m (4–5ft), or a group of smaller 60cm (2ft) plants.
Astilbes cross-breed easily, which means there are many to choose from. The parentage affects the flowering time, foliage and flower colour, style of flower and height. See our lists of tall and dwarf hybrids which are also arranged by flower colour:
Choosing astilbes: tall forms
Choosing astilbes: dwarf forms
The main groups are:
- Astilbe × arendsii hybrids – these are tall hybrids (mixes of different species), 60–150cm (2–5ft) in height, with white, pink or deep red flowers. The plumes taper at the tip, some are upright, others more lax. Their parentage is mixtures of Astilbe chinensis, A. grandis, A. chinensis var. davidii, A. japonica and A. thunbergii
- A. chinensis hybrids – flowering in late summer, the pink or white blooms are very upright. These plants make tough ground cover
- A. japonica hybrids – these have distinctly glossy leaves and bloom in early summer, with loose flower plumes
- A. simplicifolia hybrids – these are compact, 60cm (24in) tall at the most
How and what to buy
Astilbes are widely available in garden centres and nurseries from spring to autumn.
They are most often sold in 2–3 litre containers, but in spring you may find young plants in 9cm (3½in) pots. These smaller plants will establish very well and are even preferable to the larger sizes, as they will get used to their growing conditions from a young age.
Nurseries sometimes sell
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
When to plant astilbes
Like most perennials, astilbes are best planted in spring or autumn (late September to mid-October), so they can begin to establish well in warm but not hot weather. Water several times a week throughout their first summer.
If bought in summer in flower, plant straight away and be sure to water generously and regularly, especially during hot, dry weather – see Ongoing Care, below.
Where to plant astilbes
Astilbes need rich, moist soil. So dig in plenty of well-rotted organic matter before planting, to improve the soil – add about a bucketful per sq m (sq yd).
Choose a lightly shaded area for best establishment. Be aware that in a very sunny spot, the foliage may scorch in high summer, and the soil is liable to dry out more quickly.
A bog garden or naturally damp area beside a pond or stream, where the roots can access water as they need to, is ideal. If you don’t have any of these, that’s fine – you can plant in any soil that doesn’t dry out in summer.
Dwarf astilbes can also be planted in containers, but be aware that they will always need regular watering throughout the growing season.
Top Tip
Although astilbes like damp soil, they don’t like waterlogged conditions. If you think that your ground may be too wet, see our guide to assessing whether you need to install drainage.
How to plant astilbes
Astilbes are quick and easy to plant, whether in borders or containers. Simply follow our step-by-step guides below.
Take particular care to water them generously after planting, and make sure they don’t dry out subsequently.
Only dwarf cultivars, 30–90cm (1–3ft) tall, are suitable for containers.
Perennials: planting
RHS guide to planting in containers
Watering
With newly planted astilbes, water generously two or three times a week for the first growing season, until they die down for the winter.
After their first year, astilbes growing in soil that holds onto moisture should only need watering if the ground starts to dry out. Check whether the soil is dry at a depth of 2.5cm (1in), and if so, give a long deep soaking, rather than little and often. Ideally use collected rainwater rather than mains water.
If your soil tends to dry out in summer, it would be better to choose a more drought-tolerant alternative. This would reduce maintenance requirements and water consumption.
Water: collecting, storing and re-using
RHS video guide to watering efficiently
Feeding
There is no need to feed astilbes that are planted in the rich, moist soil they prefer – they will be able to find all the nutrients they need.
Looking after older plants
Established clumps of astilbes should be divided every four years in spring, to keep them vigorous and flowering well. This also gives you additional new plants to fill out your borders or share with friends. For full instructions, see Propagation – by division, below.Once you have enjoyed the faded flower plumes through autumn and winter, cut all the stems and old leaves right down to ground level. This is best done in December or January, before new shoots start to appear in spring.
Perennials: cutting back
Wildlife-friendly gardening
The faded stems and leaves of perennials such as astilbes provide food and shelter for various small creatues over winter, so it’s best to delay cutting back until spring.
By division
The easiest way to make more astilbe plants is to dig up established clumps and divide them in spring. See our step-by-step guides below.
Perennials: dividing
RHS video guide to dividing perennials
By seed
If you leave the faded flowerheads in place, astilbes may well self-seed, and new young plants will appear nearby in spring and summer. This can result in some interesting flower colours, since the offspring may not be identical to the parents. It takes about three years for seedlings to reach flowering size.
If you’re lucky enough to have this happen, you can move the young plants to their permanent positions when they are large enough to handle, in late September or March–April. Or, if they are in suitable positions with enough space, simply leave them where they have naturally chosen to grow.
Given the right growing conditions, astilbes are largely robust and trouble-free – vine weevils are the only, occasional issue. Look out for tell-tale semi-circular notches nibbled along leaf margins by the adult weevils.
In hot, dry conditions you may see signs of scorch on astilbe foliage – this is likely to be due to weather damage and/or a problem with establishment.
Get involved
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