How to plant gladioli for summer

If you're looking for drama, height, and a serious pop of colour — look no further than Gladioli, or as they’re charmingly known, Sword Lilies. With their tall, elegant flower spikes and sword-shaped foliage, they bring a sculptural quality to the garden that I absolutely love.

They’re perfect for mixed borders, prairie-style plantings, or even modern gardens. I like to weave them through grasses, alliums, and camassias — it gives that wild-but-curated look that’s so effortlessly beautiful. Plus, they’re one of the best flowers for cutting — vase life is long, and the colours are bold.

You’ll often see them in supermarkets because they are a great british flowering crop, its a good sign for your garden!

How I Plant and Grow Gladioli in Spring

These summer stunners are easy to grow and reward you with weeks of colour. Here's how I get mine off to the best start:

Planting Basics

• Timing: I plant corms in April or May, after the last frost.

• Depth: About 15–20 cm deep

• Spacing: Roughly 10–15 cm apart

• Soil: They like fertile, well-drained soil - I find this makes quite a difference.

• Light: Gladioli love the sun, so pick the sunniest spot in the garden.

For a full, impressive display, I plant around 30–50 corms per square metre.

Feeding & Ongoing Care

• Once flower spikes appear, I feed every 2–3 weeks with a high-potash fertiliser (like liquid seaweed) to encourage strong stems and lots of flowers.

• Water during dry spells, especially when buds are forming.

• In autumn, I add a thick organic mulch to protect the corms, in the mild winter this is enough to see them through.

• Every few years, I lift, divide, and replant — it’s a great way to refresh your display and grow on any small bulblets (just keep in mind they’ll take a few years to bloom!).

 Pro tip: Gladioli can cause skin irritation, so maybe wear gloves. 

Design Tip:

Whether you’re into cottage charm or modern minimalism, Gladioli fit in beautifully. I plant them in groups for impact or weave them between ornamental grasses and summer perennials to keep the garden looking full and vibrant well into late summer.

Common Pests & Problems — And How I Handle Them

• Aphids: Can weaken plants and spread viruses. I pick them off or use an organic spray early in the season.

• Thrips: These tiny pests suck sap and can cause flower buds to fail. At the first sign (white flecks or misshapen buds), I cut back affected foliage and treat them with a spray. Although they are extremely hard to shift. 

• Botrytis (grey mould): Usually from moisture + poor air flow. I space my plants well, avoid wetting the leaves, and remove any affected material.

• Viruses: Especially cucumber mosaic virus, which can affect corms on allotments. I avoid reusing soil in affected areas and never compost infected plants.

Frequently Asked Questions (FAQ)

Q: When should I plant Gladioli in the UK?
A: April to May, after the risk of frost has passed. Or you can pot them up early and transplant into your beds. (if you have space)

Q: How long do Gladioli take to flower after planting?
A: Typically 10–12 weeks, spring—spring-planted corms bloom from mid-to-late summer.

Q: Do Gladioli come back every year?
A: Yes, in milder areas. In colder parts, they’ll need lifting and storing over winter or at least a protective mulch.

Q: Can I grow Gladioli in pots?
A: You can, though they’ll need deep containers, staking, and regular feeding.

Q: Should I deadhead Gladioli?
A: Yes! Removing spent flowers encourages more energy to go into the corm for next year’s growth.