how to plant, grow & care for gladioli
complete growing guide
Gladioli are magnificent flowers that add structure and elegance to the garden. With wonderful textures, rich and bright colours and unusual shapes, they can be both classy and striking, and can light up a sunny border in summer. Gladioli are, in many ways, like the summer tulip – they make fantastic cut flowers and growing them is easy. Like all good garden bulbs, if you get them growing in the ground, they will flower. You’ll find all of my favourite varieties in our range of top-size gladioli corms.
details
- Common name: Gladioli
- Latin name: Gladiolus
- Type: Tender Perennial
- Height: Some gladioli reach about 60cm (2ft), other varieties reach 1.2m (4ft)
- TLC rating: Easy
- Aspect: Full Sun
- Planting position: Borders, Containers
- Suitable for pots: Yes
- Good for pollinators: Yes
- Good for cut flowers: Yes
calendar
how to grow gladioli
where to grow gladioli
Soil type: Gladioli need rich but well-drained soil. On my heavy clay I add 2cm (1in) of sand or horticultural grit to the base of the hole.
Aspect & position: A sheltered position in full sun is best for gladioli.
when to plant gladioli
You can start off your gladioli in pots in March or April, but make sure you can put them somewhere bright and cold, but frost-free. Gladioli can be planted directly in the ground in May – they can be planted a couple of weeks before the last expected frost, usually early May depending on where you live.
how to plant gladioli
planting gladioli corms in the garden
Corms can be planted directly in the garden from May to July. Use a bulb planter to create holes about 15cm (6in) deep. The collar of the hole helps to keep the plants upright. If you are gardening on heavy clay, add 2cm (1in) of sand or horticultural grit to the hole. Plant your corm in the hole, fill with soil, then mulch with compost. This will help feed the bulbs and will also retain water.
If you have bought quite a few corms, don’t plant them all at once. Plant fifteen corms every couple of weeks from early May to July to give a succession of flowers through the summer and autumn.
Gladioli will need staking. To avoid piercing the corms, canes are safest poked in before you plant them.
Gladioli will flower three months after planting.
growing gladioli in a pot
You can start off your glads in pots in March or April, but make sure you can put them somewhere bright and cold, but frost-free. Otherwise, plant your corms in containers May–July (they can be planted a couple of weeks before the last frost is expected).
Use a good quality peat-free compost. For larger varieties use a container that is around 40cm (16in) in diameter and plant corms about 10-15cms (4-6in) apart. If you have smaller pots, opt for compact gladioli varieties.
Keep the pots in a sheltered position in full sun. When the flower spike emerges, feed them every couple of weeks with a liquid fertiliser.
Make sure you continue to water gladioli in containers throughout the growing season, as they will dry out more quickly than those in the ground. Stop watering as the leaves yellow, then lift and store the corms over winter.
how to care for gladioli
watering
Water regularly during the summer season, paying particular attention to gladioli in containers, as these will dry out more readily. On well-drained soil, extra watering will be required – adding a mulch of compost will help to retain moisture.
fertilising
Apply a high potash feed, like comfrey pellets or tomato fertiliser, every two weeks as soon as the flower spikes emerge and until at least three weeks after flowering. This is essential on poor soils as flowering can diminish in successive seasons.
staking
Tall varieties of gladioli will need to be staked. It’s better to push the canes into the ground before planting the corms to avoid damaging the bulb.
deadheading
To tidy up each stem while the gladioli are in flower, remove faded florets to keep the stem looking fresh. Cut the stem back when all flowers have opened and leave the leaves to continue to photosynthesise, providing food for the corm for the following year.
propagating
Over time, clumps of gladioli get congested, with new cormlets forming every year – this results in weaker plants with lots of foliage and diminished flower spikes.
You need to dig up and divide the clumps every few years and select the best corms for replanting. This will give you more plants with healthier growth.
overwintering
It's always said you need to lift your gladioli, and that like dahlias, they'll be frosted if left in the ground. I’ve grown them at Perch Hill for years and I've never lifted them.
Instead, I mulch them deeply with 6-7cm (2.5in) of compost to give them an insulating duvet over their heads in late autumn.
You should be safe with this in the south of England and the western fringes of the British Isles, but in colder areas, they will need to be lifted and brought undercover.
If they are growing in pots, stop watering when the leaves turn yellow, cut them down to about 10cm (4in), then dig the corms out of the compost and place in trays somewhere cool and dry for a couple of weeks.
After this time, shake off any loose compost, snap off the remaining stem and any shrivelled corms that may be attached to the main healthy corm. The same applies to corms that are being lifted from the ground.
The dry healthy corms can then be stored somewhere cool and frost free over the winter – hang them in a mesh bag for good air circulation.
Any new small cormlets that have formed around the base of the main corm can be picked off and potted up. These will need to be grown on for a few years before they reach flowering size.
seasonal checklist
spring
- Start off gladioli in pots in March and April, giving you established plants ready for your borders from May onwards.
- From May, plant corms directly in the ground or in containers outside.
summer
- Continue to water and feed your gladioli.
- Bring cut flowers indoors.
autumn
- Mulch any corms you’re leaving in the ground. Or lift gladioli corms and store them over winter.
winter
- Plan ahead and choose your gladioli for the spring.
pests, diseases & common issues
thrips
Tiny, winged insects called thrips can affect gladioli; you’ll know these sap-sucking insects are about when pale patches followed by a silvery sheen appear on the leaves. The gladioli buds may also fail and flowers may be mottled or turn brown. To identify thrips, look for tiny insects on leaves. Tackle them with an organic pest control.
why are my gladioli falling over?
Gladioli can reach around 1.2m (4ft) tall, and taller varieties will need to be staked. A sheltered position (alongside a fence or wall) can also minimise wind damage.
why are my gladioli drooping?
Water your gladioli regularly throughout the growing season, paying particular care to water plants in pots or growing in free-draining soils.
why are my gladioli blind?
If your gladioli corms have been overwintered in the ground, the frost may have got them. Make sure to overwinter the corms appropriately.
why hasn't my gladioli flowered?
Gladioli need plenty of water to flower well. Once they have started flowering, they will also need regular feeding.
why are my gladioli leaves turning brown?
You gladioli may be infected with thrips, or the corm may have been affected by a fungal disease. Gladioli are not evergreen so their leaves will die off in autumn.
frequently asked questions
are gladioli poisonous to cats, dogs & humans?
Yes, unfortunately, gladioli are poisonous to pets and can also be toxic to humans.
are gladioli good for bees?
Yes, gladioli are bee- and pollinator-friendly.
what does gladiolus mean?
Gladiolus is from the Latin meaning ‘little sword’, referring to the shape of the leaves.
do gladiolus spread?
Gladioli is a clump-forming tender perennial and if protected from the winter frosts will return year after year. If clumps get congested, lift and divide.
where do gladioli originate from?
Gladioli originates from South Africa, the Mediterranean and Asia.
which way to plant gladioli bulbs?
Plant gladioli corms with the slightly pointed end facing up, there is a noticeable root scar on the base.
can gladioli be grown indoors?
Gladioli can be grown successfully in a greenhouse, which can be a solution if you live in a cold part of the country.
will gladioli grow in shade?
Gladioli need a position in full sun to flower well.
how to cut & arrange gladioli
With rich, bright colours and wonderful textures, gladioli are perfect cut flowers. When cutting them for a vase, remove the bottom leaves. The tip of the flower spike can be pinched off, which will encourage the flowers further down the spike, but I think the tip is part of the plant’s appeal and prefer to leave it on.
Get more inspiration for displaying your flowers with our flower arranging videos:
