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Gladiolus papilio 'Ruby' and Lobelia 'Tania'
© Jason Ingram

The best summer bulbs to plant in spring – expert picks

Published: February 16, 2022 at 9:25 am

Spring is the ideal time to plant summer-flowering bulbs. We asked four experts to recommend their favourites

While we're enjoying the long-awaited colour from spring bulbs, it can be easy to forget that spring is the best time to plant summer bulbs. Dahlias, gladioli, lilies and more can all be planted in spring for colour through summer and autumn.

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We asked four experts to recommend their favourite summer-flowering bulbs: Jo Thompson, one of the UK's leading garden designers; Carien van Boxtel, a garden and landscape designer known for her designs using bulbs; Charlie Ryrie, founder of The Real Cut Flower Garden, which supplies sustainably grown flowers and Steve Lannin, head gardener at Iford Manor in Wiltshire.

Below is a selection of their top choices.

When to plant summer bulbs

Plant summer-flowering bulbs in spring – you will start seeing packets of bulbs in garden centres from late winter.

Where to plant summer bulbs

Most summer-flowering bulbs do best in a warm, sunny spot and well-drained soil. For the best displays in borders, grow in groups or drifts of at least six or seven. If you don't have the right soil conditions, summer-flowering bulbs grow very well in pots – you could add some horticultural grit or sand to the compost before planting to aid drainage. Read our expert advice on growing bulbs in pots.

How to plant summer bulbs

Most summer bulbs need planting at two or three times their depth, pointed end up (amarines like to have their nose 'proud' of the soil). Water in well after planting.

Start dahlia tubers off in March. Plant with the central stem pointing up, just below the surface of the compost and water in. Keep them somewhere frost-free until they can be planted outside in late May.

Caring for summer bulbs

The more tender types of summer bulbs, including dahlias and amarines, should be mulched over winter in colder areas, or lifted and stored in a frost-free place over winter.

Summer bulbs: experts' picks

Dahlias

Dahlia merckii
Dahlia merckii. © Jason Ingram © Jason Ingram

Carien van Boxtel recommends Dahlia 'Merckii': "It's extremely elegant with small, star-shaped flowers at the end of thin stems, and lovely fine foliage." She also loves Dahlia 'Josie': "Perfect for containers, it flowers early in the season. Its semi- single flowers are a wonderful bright orange and attractive to pollinators."

Jo Thompson recommends Dahlia 'Café au Lait Rosé', bred from the popular 'Café au Lait'. "It has large, double blooms with broad pointed petals in the most charming of pinks." She also loves Dahlia 'Penhill Watermelon': "The huge, glamorously shaggy flowers, with twisting, pointed petals of peachy-pink, are produced in profusion over a long period and last well in the vase, too."

Steve Lannin flies the flag for Dahlia 'Sweet Nathalie', a decorative type with densely petalled flowerheads. "It's the lightest of coral pinks – a lovely cutting flower that blends well with stronger pinks and peaches."

Read about designers' favourite dahlias.

Heights vary. RHS H3, USDA 7a-10b.

Amarines

Amarine tubergenii Belladiva Series
Amarine tubergenii Belladiva Series. © Jason Ingram © Jason Ingram

Amarines are a cross between Nerine bowdenii and Amaryllis belladonna. "They are extremely popular as elegant cut flowers," says Carien Van Boxtel. "But I prefer them in borders between grasses and asters, and arranged with other other pink and magenta autumn bulbs, such as Colchicum autumnale."

50cm. RHS H5, USDA 5a-9b.

Read our expert advice on planting nerines and amarines.

Gladiolus papilio 'Ruby'

Gladiolus papilio 'Ruby' and Lobelia 'Tania'
Gladiolus papilio 'Ruby' © Jason Ingram © Jason Ingram

While Carien van Boxtel favours the species, Gladiolus papilio ("It has strangely beautiful hues of mauve, salmon, purple and green"), Jo Thompson adores Gladiolus paplilio 'Ruby'. "It has sumptuous velvet tones of deep red to burgundy and combines well with grasses or Eupatorium maculatum and red Persicaria."

90cm-1.2m. RHS H4, USDA 4a-10b.

Crocosmia

Crocosmia x crocosmiflora 'George Davison'
Crocosmia x crocosmiflora 'George Davison' © Alamy ALAMY

"Crocosmias are fantastic hardy corms that will provide lovely foliage and flowers as well as decoratative seedheads," says Carien van Boxtel. "The bold reds and orange shades are better known, but I love a yellow, both the garden and the vase." She particularly recommends Crocosmia x crocosmiflora 'George Davison'.

75cm. RHS H5, USDA 5a-9b.

Martagon lily

Lilium martagon Turk's cap lily Getty Images
Lilium martagon © Getty Images Getty Images

"Turk's cap lilies (Lilium martagon) are often grown as woodland plants in part shade, but they will also tolerate sun and look great when naturalised in open grass," says Jo Thompson. The species produces an abundance of small, pinky-purple downward-facing flowers with reflexed petals.

1.5m. AGM. RHS H6, USDA 3a-8b.

Agapanthus

Agapanthus 'Windsor Grey'
Agapanthus 'Windsor Grey' © Alamy ALAMY

Two of our experts recommended agapanthus in shades of white instead of the usual blue. Steve Lannin picked Agapanthus 'Windsor Grey': "It's greyish-white, with a subtle lavender blue blush to the base of the flower." Meanwhile Charlie Ryrie plumped for Agapanthus 'Headbourne White', a robust, white-flowered deciduous form which is borderline hardy. "The big domed blooms, like snowballs, top straight stems in late summer."

Read more about the best agapanthus to grow in your garden.

1m. RHS 4, USDA 3a-8b.

Tulbaghia

Tulbaghia violacea © Jason Ingram Jason Ingram

Steve Lannin recommends Tulbaghia violacea: "Pale, pinkish-mauve flowerheads held in umbels of up to 20 individual flowers, amid grass-like foliage, from June to September. Hailing from South Africa, these bulbous plants need full sun and well-drained soil."

40cm. AGM. RHS H3, USDA 7a-10b.

Dierama

Dierama pulcherrimum 'Merlin' © Torie Chugg

Steve Lannin loves Dierama pulcherrimum 'Merlin'. ''It has grass-like foliage coupled with sultry, black-red flowers that dangle from long, thin arching stems and dance in the wind," he says. "Ensure full sun and moist but well-drained soil."

1m. RHS H4, USDA 8a-10b.

Liatris spicata

Liatris spicata © Getty Images Getty Images

"Liatris spicata has tall flower spikes that bear distinctive, tufted, bottlebrush-style flowers in a deep mauve," says Steven Lannin. "Fresh growth appears in spring (keep an eye out for hungry slugs) with flowers in late summer. Liatris spicata is best planted in full sun. It's attractive to bees and butterflies and a good cut flower."

80cm. RHS H7, USDA 3a-3b.

Ranunculus asiaticus

Ranunculus asiaticus Getty Images
Ranunculus asiaticus © Getty Images Getty Images

"The double-flowered forms of Persian buttercups, with their ruffled layers of crepe-paper like petals, are often planted to overwinter," says Charlie Ryrie. "But are very successful if planted in late winter for summer flowering, as long as there's still some cold weather on the horizon."

45cm. RHS H4, USDA 4a-10b.

Ornithogalum saundersiae

Ornithogalum saundersiae Getty Images
Ornithogalum saundersiae © Getty Images Getty Images

"The best star of Bethlehem for cutting, lasting for weeks in the vase," says Charlie Ryrie. "It produces dense clusters of showy, star-like creamy-white blooms with black centres, which perch atop tall, straight stems."

90cm. RHS H2, USDA 10.

Tulipa ‘Ronaldo’. A triumph tulip that is suitable for the border, containers or for cutting and is very weather resistant. The burgundy-coloured flowers are held just proud of the foliage from April to May. 40cm. RHS H6, USDA 3a-8b.
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This is just a small selection of our experts' choices of summer bulbs to plant in spring for a floriferous show all season. To discover the rest, make sure to get the March 2022 issue of Gardens Illustrated, out on 1 March and on sale in all good newsagents or as a digital edition from the Gardens Illustrated App - search Apple Store, Play Store, Zinio and Kindle. You can also subscribe so you never miss an issue - see out latest deals here.

Authors

Veronica Peerless is a trained horticulturalist and garden designer.

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