When to plant gladiolus bulbs – the sweet spot to avoid frost but make it in time for vibrant blooms in summer

The regal and grandiose-looking gladioli are sure to elevate any garden with their abundant and vibrant blooms come summer. A single flower spike can produce up to 20 buds so imagine how many you could get adorning your garden from 15 bulbs, as they’re often sold. But before you get to planting your bulbs (also known as corms), you need to know exactly when to plant gladiolus bulbs.

Learning how to plant gladiolus bulbs is just as important. But you need to get the timing right to avoid frost and make sure they bloom when they’re supposed to, just in time for summer.

So if you’re wondering what the best time for planting gladiolus bulbs is, then you’ve come to the right place as our gardening experts reveal the best months to do it and why.

When to plant gladiolus bulbs

Gladioli are one of the best bulbs to plant in spring. But choosing the right month and right weather conditions is crucial. But another factor is how you’re planting them - directly into the ground or into pots first?

‘Gladioli bulbs can be planted anytime from early to late spring,’ starts Fiona Jenkins, gardening expert at MyJobQuote.co.uk.

If you’re planting straight into the ground then April to May is the best time when to plant summer bulbs.

‘You need to plant gladioli bulbs anywhere between mid April to July, with July being the very last time of year you can plant them before their growth is affected by frost,’ says Steve Chilton, garden expert at LeisureBench. ‘I would say that May is the best month to plant them, as the weather at this time should be nice and warm for these hot-weather loving plants.’

Steve Chilton

Steve is a passionate and knowledgeable garden expert with several years of experience within the field. As the director of LeisureBench, an industry-leading garden furniture company, Steve has developed strong expertise for all things nature and plants. 

But if you have an early-flowering variety, then March (so now) is best. ‘If you have early-flowering gladioli – such as gladiolus byzantinus – then they’re best planted in March or early April. As they’re typically June flowering, this gives them time to grow,’ Fiona advises.

March is also a good time to start planting gladioli if you’re planting in pots or using the best plant covers.

‘If you have a greenhouse and intend to plant them in pots, then you can from March onwards,’ Steve says.

Fiona confirms, ‘If you’re planting in pots, you can start growing your gladioli in March. Just be sure to keep them protected from frosts.’

Where to buy gladiolus bulbs:

• Thompson & Morgan: Gladioli Mixed
• J. Parker's: Gladioli byzantinus
• Sarah Raven: Hollywood Gladioli Collection

FAQs

What is the best month to plant gladiolus?

If planting straight into the ground, the best month to plant your gladiolus bulbs is either April or May to avoid the frost with certainty.

‘If you’re planting your gladioli directly in the ground, then April and May are the best months to do this as the frosts should have passed,’ Fiona says.

Will gladioli flower in the first year?

Yes, gladioli flower only about 12 weeks after planting.

‘Gladioli bloom between 10 and 14 weeks after the bulbs have been planted,’ says Petar Ivanov, Fantastic Gardeners' gardening expert. ‘The flowering season usually begins in late June and ends in early July. To make sure they flower earlier or into the autumn, you can also plant them strategically.’

So if you’re planting in pots, then you can get to planting your gladioli. Otherwise, hold off until next month or May to be safe.