12 Summer-Flowering Bulbs That Will Delight
Most people associate bulbs with spring, but there are plenty that will produce an explosion of colour in the summer and even into autumn.
Hannah, our co-owner and lead content creator, lists her 12 favourite summer-flowering bulbs, tubers and rhizomes in this guide.
She’s also published some quick tips so you can get the most out of these plants.
1) Allium Bulbs For Late Spring and Early Summer Blooms
Alliums are the perfect ornamental bulbous plant and are best grown between other plants where they rise proudly before the bloom opens into a distinctive globe.
While often grown as a late spring flowering blub, many alliums will stay in bloom until early summer and a few are late starters that are pure summer plants.
Looking beyond the classic “purple sensation” allium, consider these late starters:
Allium nigrum: Also known as Black Garlic, this allium is a late bloomer and puts on its show in early summer, usually in June. Clusters of flat white blooms, 10cm across, sit atop stems between 0.5m and 1m.
Allium sphaerocephalon: Also known as the Drumstick Allium, the blooms on this summer-flowering allium bulb are just as delightful as the immature buds. Watch as the buds gradually turn from green to red and purple. Grows to around 50cm and self-seeds but not aggressively.
- There are dozens of alliums to choose from.
- As part of the onion family, they will deter pests such as squirrels.
- Most alliums come into bloom from mid to late spring but some delight well into mid-summer.
Get started by exploring our allium growing guide.
There are hundreds of irises to choose from, and many will bloom from spring to early summer, while others, such as the bearded iris, will flower from mid to late summer and beyond.
- Plant several different irises, and you’ll see blooms from spring into early summer.
- Keep an eye out for rebloomers that put on a second show later in the summer and even as late as the autumn.
- Grow in full or partial sun.
- Taller varieties can reach 1.2 metres/4ft.
Our guide to growing spring irises is an excellent place to start, even though many will bloom well into summer.
Dahlias are grown from tubers rather than bulbs but they’re still worth a mention as they’re the ultimate summer-flowering plant with their huge blooms that are guaranteed to impress.
There are hundreds of varieties to choose from and most can be planted immediately after the last frost or started off a month earlier undercover.
- Prune off buds lightly and you’ll be rewarded with more numerous yet smaller flowers.
- Prune the buds off more aggressively and the dahlia will produce fewer but much larger blooms.
- You’ll need to stake dahlias to stop them from blowing over in the wind.
- Ideal for pots as well as borders.
How to grow huge dahlia flowers (as big as a dinner plate)
4) False Shamrock
False shamrock (Oxalis triangularis) is a perennial that’s hardy down to -5°c and is often grown in the south but can be grown as an annual in cooler climates.
- Unusual triangular leaves in deep purple from spring to autumn.
- Pink and white star-shaped flowers are on show from late spring into summer.
- Low growing and reaching a height of between 0.2 and 0.5m in around 2 years.
- Grow in pots indoors year-round.
- Grow outdoors and bring in the pot for the winter.
5) Calla Lillies
The calla lily is grown from tubers planted in the spring, and by summer, it will reward you with neat upright foliage and funnel-shaped flowers which sit atop stems to 1m.
- Grow in full sun or partial shade in a south or west-facing garden.
- Ideal for pots.
- They bloom at different times so by choosing different varieties you’ll be rewarded with flowers from spring to autumn.
- Winter hardy in milder climates otherwise, lift and overwinter the tubers or just grow them as annuals.
- Calla lilies make excellent cut flowers with a long vase life.
How to grow calla lilies (video)
While a member of the previously stated iris family, crocosmia is worth its own entry.
Thick grassy blade-like foliage surrounds arching fiery orange blooms atop 50cm stems.
Crocosmia is often grown for its brightly coloured flowers and to attract pollinators.
- Reaches up to 1m tall.
- Green grassy foliage from spring into mid-autumn.
- Orange and pinkish tubular blooms arrive in the summer.
- Deciduous and clump-forming.
- Plant in full sun or partial shade.
The Ultimate Crocosmia Planting Guide by Easy to Grow Bulbs
7) Freesia Summer Flowering Bulbs
As a tender perennial, freesia performs best in a conservatory or on a warm patio protected from the winter cold.
Heat-treated corms (bulbs) can be planted in the spring for an early summer flowering in their first year.
- Highly scented.
- Perfect for hot patios where the pot can be brought into a conservatory for the winter.
- Flowers from June to August.
- They make delightful cut flowers.
Read: How to grow freesia bulbs.
Gladioli have it all; deep rich colours, unusual flowers, tall stems and they make for wonderful cut flowers.
If you live in the south, you can leave gladioli bulbs in the ground, just mulch with a few inches of organic material to protect them from the frosts.
If you live anywhere else in the UK, you may need to lift and store the bulbs over winter.
- Taller gladioli will need staking.
- Can be started off in pots from April or plant them directly in the border after the last frost.
- A popular pot plant.
- Gladioli will flower 3 months after planting so you can sow the bulbs every week from late April to June and you’ll be rewarded with blooms for nearly 4 months.
- This plant prefers full sun with a little shelter from the wind.
9) Hyacinth (Forced)
Hyacinths are a popular compact spring-flowering plant that produces pastel-coloured blooms that will delight in the garden or in the home.
Hyacinths can be grown indoors at any time of the year and forced to bloom outside of their usual season.
Hyacinths are perfect for apartment owners snd are easy to grow and carefree.
- Hyacinths are compact and rarely grow taller than 35cm.
- Prefers a sunny spot and will produce smaller blooms if grown in the shade.
- Perfect for window boxes, sills, apartments and pots on patios.
10) Ranunculus (Persian Buttercup)
Persian buttercups make excellent cut flowers and their rose-like blooms look stunning in borders, pots and vases.
Plant out in the autumn if you live in a mild area, otherwise wait until the risk of frost has passed in the spring.
These perennial plants are grown from tubers that resemble claws and depending on your area, they will require a thick winter mulch for frost protection or they should be lifted and stored.
- Will reach up to 45cm tall.
- Perfect for containers.
- The tubers are easy to split and propagate.
- Flowers from late spring into summer, usually 70-90 days after planting.
- Prefers full sun.
Begonias are perfect for patio containers, troughs, and even hanging baskets where their explosion of colourful rosette-like blooms won’t go unnoticed.
There’s no need to buy established expensive plugs; the tubers are cheap, easy and reliable to grow.
While begonias are tender perennials (meaning the tubers should be lifted in the winter), they flower for a very long period, often from mid-summer through to the first frosts.
- Start the tubers off in March or April in a greenhouse or sheltered spot.
- Harden off and transplant to the garden after the last frosts.
- Position in full sun or partial shade.
- Height: up to 20cm Width: up to 50cm.
Aamarcrinum is a cross between Amaryllis and Crinum and rewards the gardener with lily and funnel-like blooms atop sturdy stems to 60cm and upright foliage.
- Start off the bulbs in the spring, keeping the top of the bulbs just below ground level.
- Position in full sun in airy, light soil.
- Blooms from mid-July to October.
- Evergreen in milder climates and frost hardy to minus 5°c.
When Should Summer-Flowering Bulbs Be Planted?
The best time to plant summer-flowering bulbs will depend on the species of plant, but most will need to be put into the ground or container in the spring, only a few will need to be started in the autumn.
If you live in a mild climate, you can probably set the bulbs directly into the garden, but those in cooler areas should consider starting off the bulbs in a container in a greenhouse, conservatory or even on a bright windowsill until the risk of frosts has passed.
Those living in the south of the UK may be able to leave the bulbs in the ground over winter, although a thick mulch would offer extra frost protection. Those in cooler areas may need to lift the bulbs and store them until the risk of frosts has passed.
The Difference Between Bulbs, Tubers and Rhizomes
Gardeners often describe bulbs, tubers and rhizomes as “bulbs” and for most intent and purposes, there isn’t much difference between the three but technically, they aren’t the same.
According to flowerbulbs.com
A true flower bulb is similar to an onion: a flower bud surrounded by scales that contain nutrients.
Rhizomes are underground stems that run horizontally below the surface.
Corms, tubers and rhizomes are not made up of individual scales (as true bulbs are) but are a solid material. Their food reserves are stored in their fleshy roots (corms, tubers and root rhizomes) or stems (stem rhizomes). Located on the surface of these underground storage organs are axillary buds (eyes) from which the roots and shoots emerge.
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More From Hannah Miller:
This guide to the best summer-flowering bulbs, tubers and rhizomes was created by Hannah Miller and was published on DIY Gardening on the 1st June 2022.
Discover more content at Hannah’s Corner.
Hannah is a keen amateur gardener, mother and former NHS administrator.
She enjoys gardening as much as she cares about the environment and likes to share her knowledge with others.
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