The best perennial plants to buy now and enjoy forever, according to garden experts

If there's one thing we love, it's a comeback kid – especially when it comes to our garden – so sussing out the very best perennial plants, then, is an absolute must

Filling your outdoor space with perennials (aka plants and flowers that live for multiple growing seasons) is one of those budget-friendly garden ideas that never goes out of style.

Oh sure, there are a handful of perennials to avoid in the garden. And, sure, not all perennials live forever. But overall, perennials are a brilliant way to fill your outdoor space with colour and interest in every season, of course – and they're guaranteed to come back year after year, too.

There are, though, the experts really rate when it comes to filling your flower beds, garden borders, and even containers. We've asked them and these are the ones they'd recommend stocking up on.

1. Hardy geraniums

Nothing beats growing geraniums in window boxes or flowerbeds for a burst of vibrant colour. 'Hardy geraniums are excellent in general. My favourite, ‘Rozanne’, is a bushy mound-forming perennial with masses of beautiful, large (up to 5cm across), saucer-shaped, violet-blue flowers,' says Morris Hankinson, director of Hopes Grove Nurseries.

Morris Hankinson

Morris Hankinson is the founder and managing director of Hopes Grove Nurseries Ltd, the UK’s only specialist grower-retailer of hedging plants. He established the thriving business in 1992, shortly after graduating with a Commercial Horticulture Degree from Writtle College, Essex.

'Flowering from June to September, these hardy plants are ideal for suppressing weeds at the front of a mixed or herbaceous border, and will keep your bees and other pollinators happy for months!'

Just be sure that this wildlife garden essential enjoys full sun to partial shade in fertile, well drained soil.

2. Switch grass

'Commonly known as switch grass, this deciduous, perennial grass grows to 1.8m tall, ideal for adding ground coverage where needed,' says Melbourne-born and London-based exterior designer Melanie Hick, who created the ‘Climate-Forward Garden’ – a Get Started garden at RHS Hampton Court Garden Festival.

'Not only that, but it adds some pretty colour too, with airy sprays of tiny, purple-green flowers produced from mid-summer to early-autumn, and the leaves themselves turning a beautiful rich reddish-purple colour later in the year,' she continues.

'Switch grass is proof that hardy plants can be both functional and beautiful, originating from North America, where it is dominant in prairie-land and famous for being both resource-efficient and low-maintenance – ideal for a sustainable, climate-forward garden.'

3. Salvia nemorosa

Considered to be one of the best perennial plants by experts, Morris says it's important to 'give salvia full sun or a little shade and they will cover ground quickly and provide spires of pretty colour from purple to pink'.

'Clumps can be divided every 3 to 4 years so you can grow even more free plants,' he adds, noting that they will grow to a maximum of about 50cm high.

'Your garden pollinators will love them, and they will carry on growing for years to come.'

3. Yarrow

'I added bursts of vibrant colour to my RHS Hampton Court garden by using Achillea Millefolium, or yarrow, a spreading perennial topped with domed flowerheads of small, dark pink rose-pink flowers,' says Melanie.

'This is a wonderful plant to introduce to gardens for wildlife – birds can use yarrow to line their nests, while many insects, including beetles and moths, feed on the plant. As a result, yarrow is often a favourite to use in butterfly gardens.'

One of the very best perennial plants, you can pick up your own Achillea millefolium 'Salmon Beauty' from Sarah Raven in pots of three or six.

4. Verbena bonariensis

'With its tall stem of bright lilac/purple flower heads, verbena is an easy plant to grow because it readily self seeds,' says Morris.

'The flowers are beneficial for pollinators and give willowy height in a herbaceous border. Used in flower arranging as well, verbena bonariensis will grow well in a warm, sunny garden space with well drained soil.'

5. Kniphofia

Another of Melanie's picks for the best perennial plants, 'Kniphofia, also known as red-hot pokers, boasts exotic looking flowers which add yet another pop of colour into climate-forward gardens'.

'They flower throughout much of the year – from March to November – so are ideal for adding colour into gardens through all but the winter,' she says.

'Colours are wild and varied – from red and orange, through to yellow and green, and even brown and pink. Growing up to 210cm, they are also ideal for adding some height and creating zones in gardens, or even privacy from neighbours!'

6. Bergenia

One of the best perennial plants for a part shady spot or a north-facing garden, Morris says that 'bergenia like well drained, good soil as they don’t grow so well in poor soil conditions – however that can lead to lovely reddish foliage in winter which looks great'.

Growing to a maximum height of 1.5m, it is a clumps-forming plant so over time will fill out a border,' he adds, noting that 'these can be split to keep in place or to produce new plants'.

7. Red Damask

The very best perennials add colour and interest to a garden all year long, something which this little beauty does in abundance.

'Adding vibrant hues to my RHS Hampton Court garden is Leptospermum scoparium, or ‘Red Damask’, a dense medium-sized shrub which will flower from late spring,' says Melanie.

'Those who love adding flashes of colour to their gardens will adore this plant, as it provides deep pink-reddish flowers, set off beautifully against narrow, dark-green leaves. These pops of bright colour against a backdrop of muted, warm hues are a key element of my garden design. The Red Damask is provides much of that interest, leading the eye around the garden.'

FAQs

What is the longest flowering perennial plant?

If you're looking for one of the longest flowering perennial plants, look to the salvias, the yarrows, and the kniphofias that are readily available online and in garden centres across the country.

What is the most popular perennial plant?

Lavender, sedum, and hardy geraniums are considered to be the most popular perennial plants. Not only are they all stunning, but they thrive in tricky conditions, too, making them the obvious choice for even the very greenest of gardeners.

Morris Hankinson of Hopes Grove Nurseries, however, adds that you shouldn't dismiss trees and shrubs when considering the best perennial plants for your garden.

'As the saying goes, "Yesterday is the time to plant a tree",' he explains. 'Shrubs and trees will grow for many years and there are so many to choose from depending on the size of your garden.'

Morris adds: 'From fruit trees beneficial for you and wildlife to trees that change foliage colour depending on the season, there is a tree or two for every garden. Shrubs are easy to maintain and will grow for many years and should always be considered for structure and interest in a garden.'

Now that you know the very best perennial plants around, all that's left for you to do is decide which you'd like to plant in your garden.