12 of the Best Summer Flowering Bulbs: By a Horticulturist (2024)

This list was thoughtfully compiled by gardener Hannah Miller and reviewed by horticulturist Elizabeth Smith. Published to Ideas on the 1st June 2022. Updated: 16th February 2023.

We independently research, combine and grow plants in our gardens. If you buy something via links, we may earn a commission. Explore our editorial process.

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.

I Recommend:

Looking beyond the classic “purple sensation” allium, I have previously grown 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. I like how the buds gradually turn from green to red and purple. Grows to around 50cm and self-seeds but not aggressively.

Key points:

• There are dozens of alliums to choose from.
• As part of the onion family, they will deter pests such as squirrels, and I’ve never had any serious issues growing them.
• Most alliums come into bloom from mid to late spring, but some delight well into mid-summer.
• In my garden, I leave stems in place as they add interest, even after the blooms have faded.

Explore more:

Get started by exploring our allium growing guide.

2) Iris

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.

Key points:

• I’ve had success planting several different irises, and could see that they bloomed in stages from spring into 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.

Resources:

Our guide to growing spring irises is an excellent place to start, even though many will bloom well into summer.

3) Dahlias

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.

I’ve been growing dahlias for years and in my garden, they bloom all the way through to the first frosts.

There are hundreds of varieties to choose from and most can be planted immediately after the last frost, although I usually start some off a month earlier undercover.

Key points:

• I prune off lots of side buds to encourage huge blooms.
• However, if I want smaller yet more numerous flowers, I trim off fewer buds, if any at all.
• I’ve found that dahlias need stakes or frames to hold them upright.
• In my garden, I’ve found they grow well in mid-to-large containers but they can get top-heavy.

Resources:

How to grow huge dahlia flowers (as big as a dinner plate)

Learn how to grow dahlias in pots.

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.

Key points:

• 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.

Resources:

How to grow false shamrock inc indoors

5) Calla Lilies

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.

Key points:

• 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 grow them as annuals.

I’ve grown calla lilies before and they weren’t difficult to look after and made for lovely cut flowers

Resources:

How to grow calla lilies (video)

6) Crocosmia

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.

Key points:

• 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.

My Experience with Crocosmia:

I had these at my previous property, and they were very reliable, required no care or attention and produced the most delightful flowers.

Resource:

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.

Key points:

• Highly scented.
• I’ve grown these in containers on my hot patio before, and I brought into a conservatory for the winter.
• Flowers from June to August.
• They make delightful cut flowers too.

My Experience With Freesia:

I lost a few of these as some didn’t recover from their winter slumber. Based on my experience, they aren’t the most reliable plant.

Resource:

Read: How to grow freesia bulbs.

8) Gladioli

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.

Key points:

• 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.

My Experience With Gladioli

I lost many of mine over winter in 2018, despite living in the south of the UK, so if I grow these again, I will definitely lift them or pad them out with some insulating mulch for the winter.

Resources:

How to grow gladioli bulbs.

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 and are easy to grow and carefree.

Key points:

• Hyacinths are compact and rarely grow taller than 35cm.
• Deciduous.
• Prefers a sunny spot and will produce smaller blooms if grown in the shade.
• Perfect for window boxes, sills, apartments and pots on patios.

My Experience

I grew these on a windowsil in my previous house about ten years ago. The blooms started off very big, but the following year, they got smaller until they didn’t bloom at all. They were fun to grow though and I would try them again, if I had the space on my sils.

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.

Key points:

• Will reach up to 45cm tall.
• I think they look lovely in containers.
• The tubers are easy to split and propagate.
• In my garden, they flower from late spring into summer, usually 70-90 days after planting.
• Prefers full sun.

My Experience

I’ve grown these in pots for years and have found that if given some winter protection, they come back reliably.

11) Begonias

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; I’ve always found the tubers 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.

Key points:

• I usually start the tubers off in March or April in a greenhouse or sheltered spot but you don’t have to.
• 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.

12) Amarcrinum

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.

Key points:

• 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, I live in Surrey and this sometimes works for me.

Those of you that live 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. I live in Surrey, and sometimes I can get away with leaving them in the ground, but I usually lose a few each year.

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.

and

Rhizomes are underground stems that run horizontally below the surface.

and

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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You May Also Like to Explore

If you enjoyed our guide to the best summer-flowering bulbs, you also like to explore:

When to plant bulbs (a quick guide)

What to do if your bulbs start growing too early

More:

• 15 delightful bell-shaped flowers
• 10 flowers with round heads for your garden
• 12 star-shaped flowers to brighten up your garden
• 10 pink flowering trees for any garden

Hannah is a former NHS administrator, mother of two and keen qualified gardener who loves growing new plants and experimenting in the garden.

She enjoys gardening as much as she cares about the environment and likes to share her knowledge with others.

This year is all about pollinators, and Hannah has set herself the goal of only buying new plants that attract pollinators; she aims to make the garden as bee and butterfly friendly as possible.

More About Hannah Miller

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