Perennials are the largest group of garden plants and offer magnificent diversity for every location from sun to shade. Plants range in size from ground-covering and clump-forming varieties just a few centimetres high, right up to statuesque giants a couple of metres tall. Growth is quick and most plants reach a mature size within one or two growing seasons. Perennials mostly flower in spring, summer or autumn, with a handful blooming in winter, and many have attractive foliage too.
Most perennials are herbaceous, meaning they die back to the ground in autumn and regrowing in spring. However some are evergreen and keep their leaves all year. Many perennials make good cut flowers and the more compact varieties that have long-lasting appeal are excellent for growing in pots. In borders, perennials combine well with shrubs, conifers and ornamental grasses to make attractive displays that give long-lasting interest.
Annual or perennial?
Annuals complete their life cycle within a year, flowering and setting seed before dying. Most perennials are long-lived, lasting for several years, although, strictly speaking, a perennial is any non-woody plant that lives for at least two years.
Growing perennials: jump links
- Planting perennials
- Caring for perennials
- Propagating perennials
- Where to buy perennials
- 20 perennials to grow
Choosing perennials for your garden
For the greatest success when growing perennials, choose the right plant for the right place. Assess your site, including soil type, and how moisture retentive it is, the amount of sun or shade the area gets, and how exposed it is to the wind. Then look at the bigger picture of the climate in your area – there are plants for absolutely every situation, and matchmaking their preferences to your site is worth the time and effort involved.
When to plant perennials
Autumn is the ideal to plant hardy perennials, while the soil is still warm, and plants can establish a good root system in time for the following spring.
After autumn, spring is the next best time to plant perennials, as long as plants are watered during dry spells when temperatures increase in summer. This season is best to plant plants that aren’t reliably hardy, so they have plenty of time to establish before winter.
You can plant perennials in summer, however it’s critical that the plants are kept watered for the rest of the growing season, as there’s naturally less moisture in the soil.
In mild areas, hardy perennials can be planted during winter, excepting when the ground is frozen or waterlogged.
How to plant perennials
Prepare ground thoroughly, as some perennials will be there for years. Improve soil with plenty of well-rotted organic matter or soil conditioner, remove large stones and clear all weeds, particularly the roots of perennial weeds.
Dig a hole slightly larger than the plants’ roots or pot, take off the pot and carefully unwind any roots that have spiralled around the rootball. Put the perennial in the ground so the top of the rootball is at soil level, backfill with soil, firm to remove any air pockets, and water thoroughly.
Caring for perennials
- In early spring, feed your perennials with a general slow-release fertiliser and mulch the bare soil between plants with well-rotted organic matter
- In spring or early summer, support tall-growing perennials with stakes such as canes and string, or grow-through plant supports placed over the clump
- Through spring and summer, keep the surrounding ground clear of weeds
- Remove dead and faded flowers to prolong the flowering season and to keep plants looking good
- In autumn, cut back fleshy-leaved perennials as soon as they die back, otherwise the leaves go soggy and rot
- Woody-stemmed perennial growth can be left until late winter/spring before cutting back. Frost, mist, and snow transform parchment-coloured stems into a winter wonderland, and during very cold winters, this growth also helps protect the roots from damage by severe frosts. Beneficial insects such as ladybirds hibernate in dead stems
- Tidy evergreen perennials from time to time to remove dead or tatty leaves and faded flower stems
- After three to five years, perennials tend to form large clumps and performance starts to decline. Lifting, dividing and replanting them will rejuvenate plants and provide you with more plants to grow around the garden
How to propagate perennials
Perennials are superb for the budget-conscious gardener. Many can be raised cheaply from seed, then, once perennials have formed good-sized clumps, nearly all can be propagated by division, breaking up the clump into good-sized chunks to replant while discarding the old, woody centre.
Advice on buying perennials
- Perennials are widely available at nurseries and garden centres, usually in at least two different pot sizes so you have the option of buying more costly plants for instant impact, or smaller ones that take a year or two to grow
- Perennials can also be bought by mail order – the best time to buy is autumn to spring, when plant growth is dormant, and they are more easily transported. Bare rooted plants are available whilst dormant, which avoids using plastic pots
- Perennials can also be bought as plug plants, which are small and need growing on in pots before planting in the garden.
Where to buy perennials online
20 top perennial plants to grow
Yarrow makes a colourful summer display in a sunny spot, producing large, flat heads made up of many tiny flowers, borne on stems above clumps of feathery leaves which are green or silvery in colour. Yellow varieties predominate and there are reds and oranges too.
Height x Spread: 45-75cm x 45-60cm
Michaelmas daisy, Aster
These are a stalwart of late summer and autumn borders, bearing masses of ‘daisy’ flowers on sturdy stems in brilliant pinks, mauves, and purples as well as white. An excellent plant for pollinating insects too. Prefers sun.
H x S: 30-75cm x 45cm
Elephant’s ears, Bergenia
So-called for its large, rounded, evergreen leaves, Bergenia is a tough perennial that makes excellent ground cover in sun or shade, and thrives on any reasonable soil. Large clusters of pink, white or purple flowers are borne in late winter and early spring.
H x S: 30-45cm x 45-75cm
- Buy elephant’s ears from Thompson & Morgan
- Buy elephant’s ears from Suttons
- Buy elephant’s ears from Van Meuwen
Crocosmia dazzles from early to late summer with orange, red or yellow blooms on slender stems, with the bonus of attractive lance-shaped fresh green leaves too. Great for introducing a vertical element to a border. Grow in sun or part shade, and shelter in cold areas.
H x S: 60-90cm x 30-40cm
Delphinium bears tall stems clothed with many strikingly beautiful flowers, which open over time from bottom to top so the plant gives colour for many weeks. Blue is the predominant shade, as well as white, pink and mauve. Young stems and the divided leaves are attractive to slugs and snails, which can be protected with barrier granules or an environmentally friendly bait. Grow in sun or part shade.
H x S: 60-90cm x 30-45cm
Sea holly, Eryngium
Sea holly combines handsome, often architecturally shaped or variegated leaves with tall stems of blue flowers in summer that are beloved by bees. Prefers sun and free-draining soil and is ideal in gravel gardens too.
H x S: 45-60 m x 30-45cm
Euphorbias give long-lasting interest with a combination of attractive, architectural foliage and bold heads of ‘flowers’ in colours such as lime, yellow and orange-red. These are papery bracts, not flowers, which is why they last for months rather than weeks. Many varieties keep their foliage and form through winter. This huge and diverse plant group offers something for every garden situation.
H x S: 15-120cm x 45-120cm
Geranium is an extensive and varied group of plants that are superb for border fronts, raised beds, and underplanting larger plants. Most flower in summer and length of flowering period varies hugely. ‘Rozanne’ is an outstanding variety that blooms for many months. Hardy herbaceous geraniums mustn’t be confused with frost-tender geraniums, correctly known as pelargoniums, widely used for summer pots. Most do best in sun although several species thrive in shade.
H x S: 30-90cm x 30-90cm
Hellebores are winter/spring-flowering perennials with gems like Christmas rose, Helleborus niger and Lenten rose, Helleborus orientalis. Attractive foliage is mostly evergreen and pretty flowers range in colour from white and green to shades of pink and purple. Many hellebores are happy in shade although a few require sun. Winter-flowering varieties are particularly important for bees emerging early in the year.
H x S: 30-50 cm x 30-40cm
Day lily, Hemerocallis
Day lily has colourful, lily-like open trumpet blooms borne in clusters on sturdy stems. The individual blooms last only for a day, hence the name, but are produced in profusion to give a good display over a number of weeks in summer. A wide colour range includes yellow, orange and red. Grow in full sun and fertile, well-drained soil.
H x S: 30-60 cm x 45-60cm
Heucheras are renowned for all-year foliage interest, with scalloped-edged leaves in neat clumps and an exceptional choice of colours, including lime-green, yellow, purple, and orange. Slender spires of white flowers appear in summer, but foliage is the big attraction. Grow in sun or part shade.
H x S: 30-45cm x 30-45cm
Hostas are grown mainly for their bold and handsome leaves in many subtle variations including greens, glaucous blue, and variegated with white or yellow markings. Flowers are also borne in summer, but foliage is the main attraction. Hostas thrive in full or partial shade and prefer moisture-retentive soil. However, they do have the drawback of being attractive to slugs and snails: they eat holes in the leaves and although rarely kill plants, do make the leaves unattractive. Hostas also do well in pots, where it’s easier to protect plants from slugs.
H x S: 30-75 cm x 30-75 cm
Ice plant, Hylotelephium spectabile
Ice plant provides colour in late summer and is attractive to bees and butterflies. It bears large, flat heads composed of many tiny blooms in shades of pink and red. Forms rounded clumps of handsome fleshy-leaved glaucous foliage. Grow in sun and on free-draining soil.
H x S: 30-45 cm x 30-45 cm
Iris is a huge genus, with species and varieties that offer something for almost every garden situation. Moisture-loving species thrive in boggy soil and at the pond edges, dwarf iris are good in rockeries and raised beds, while sumptuous-flowering bearded iris must have full sun and well drained soil. Most iris bloom in summer.
H x S: 15-90cm x 20-60cm
Japanese anemone, Anemone hupehensis
Japanese anemone is easy and reliable for late summer flowers, bearing tall stems of saucer-shaped flowers in white and pink. Happy in sun or shade. It does regrow from pieces of root, so aim to plant in its final position if possible.
H x S: 60-90cm x 45-60cm
Lupin is an old favourite cottage garden flower, renowned for tall vertical flower spikes clad with many little, colourful blooms in summer, above clumps of divided leaves. There’s an extensive colour range including pink, red, blue, yellow and white. The young foliage is attractive to slugs so some protection is recommended in spring when the new leaves appear. Grow in sun and good fertile soil.
H x S: 45-90cm x 45cm
Bee balm, Monarda
Bee balm bears flowers that are exceptionally rich in nectar, hence its name, as bees and other pollinating insects adore the blooms. This bold perennial forms good-sized clumps of sturdy stems topped with showy red or pink flowers in summer. Does best in full sun and good fertile soil.
H x S: 60-75cm x 1m
Oriental poppy, Papaver orientale
Oriental poppies bear enormous, showy blooms in spring and early summer, followed by decorative seedheads. Colours include pink, red, coral and white, mostly with contrasting black centres. The fern-like fresh green leaves appear very early, with flowers appearing in mid spring. Then the whole plant goes dormant and dies back by summer. Easy to grow, in any reasonable soil and in sun or part shade.
H x S: 60cm x 45-60cm
- Buy Papaver orientale from Thompson & Morgan
- Buy Papaver orientale from Suttons
- Buy Papaver orientale from Primrose
Primroses are beloved for their early flowers – prima rosa is Latin for ‘first rose’ – and our native primrose starts blooming in winter in mild areas. There’s a huge range of colourful varieties as well as moisture-loving primulas for damp soil.
H x S: 15-60cm x 15-45 cm
Lungwort sparkles with colour in spring and are both beautiful and useful, tolerating shade as well as sun and forming low spreading clumps that can be planted beneath shrubs and trees. Bees love the blue, white or pink flowers. Some pulmonarias have prettily marbled leaves, too.
H x S: 30cm x 45 cm