Corm
How to grow gladioli
Gladiolus × hortulanus
Plant gladiolus corms 10 to 15 cm deep in full sun and free-draining soil from mid April to May, a batch every fortnight, and they flower 10 to 12 weeks later, from July to September. Success comes down to three things: deep planting and a cane so the spikes stand, water once the spike shows, and leaving the leaves on for six weeks after flowering so the new corm fattens before you lift it in October.
- Hardiness
- Half-hardy, lift corms in Oct in cold gardens
- Position
- Full sun
- Soil
- Fertile, free-draining
- Ideal pH
- 6.0 to 7.0
- Water
- Moderate, regular from spike emergence
- Feeding
- Moderate feeder
Sowing and planting gladioli
WhenPlant corms mid-Apr to May in succession; flowers Jul to Sep
Starting off
Plant corms mid-Apr to May at fortnightly intervals, 10 to 15 cm deep on a 2 cm layer of grit, flat side down; flowers follow 10 to 12 weeks after planting. Cormlets found at lifting are saved and grown on for 2 years in a nursery row to reach flowering size. Hardy G. communis subsp. byzantinus is planted Sep to Oct at 10 cm and left in.
Spacing and planting
Plant corms 10 to 15 cm apart in rows or groups of ten, 10 to 15 cm deep, deeper on light soil to help them stand. Dwarf and nanus types are fine in a 30 cm pot, eight corms; tall types are not container plants.
Varieties worth growing
- 'Plum Tart'
- Large-flowered, deep plum-purple spikes to 1.2 m; one of the best for cutting and widely sold as dry corms in spring.
- 'Green Star'
- Lime-green ruffled florets that go with everything in a vase and hold their colour in sun.
- G. × colvillei 'The Bride'
- Small, early, white nanus type to 60 cm that needs no staking and suits a pot or the front of a border.
- G. communis subsp. byzantinus
- The hardy one: magenta spikes in May and June, planted in autumn and left in the ground to spread.
- G. murielae (Acidanthera)
- Scented white flowers with a maroon throat in late August and September; needs a warm spot and a long season, so start it in pots in April.
Gladioli month by month
Timings are for central England. Allow two weeks later in the north and on cold, heavy soil.
- January
Check stored corms and throw out any that are soft or mouldy.
- February
Order corms. Buy the largest grade on offer.
- March
Plant early nanus types late in the month. Prepare the ground and rake in the base feed.
- April
From mid month plant a batch every fortnight, each with its cane. Start G. murielae in pots under glass.
- May
Last plantings by the end of the month. Watch for slugs on new shoots.
- June
Tie in rising spikes. Water weekly in dry weather. Byzantinus is in flower.
- July
Potash feed starts as spikes show. Cut for the vase when the bottom floret opens, leaving four leaves.
- August
Main flowering. Keep feeding and watering. Remove faded spikes but not leaves.
- September
Late batches flower. Stop feeding when the last spike fades. Plant byzantinus corms.
- October
Lift once leaves yellow, cut stems to 2 cm and dry for two weeks. Save cormlets if you want to bulk up.
- November
Snap off the old shrivelled corm, clean and store in paper bags at 5 to 10 °C.
- December
Nothing to do beyond a check on the store.
Feeding gladioli
Low nitrogen, steady potash. A phosphorus-led base feed at planting, then liquid potash from the moment the spike shows until flowering ends. Fresh manure gives leaves and no spike.
A potassium-leaning feed supports the tall flower spikes.
Feeding plan
Planting, April to May
100 g/m², the bottom of the label range, raked into the top 10 cm. A group of ten corms covers about 0.15 m², so 15 g per group.
From spike emergence until the last floret fades, every 2 weeks
Potassium Rich Fertiliser 11% K
0.5 to 1 g per litre of water, so 5 to 10 g in a 10 litre can, poured along the row. One can does about 2 m of row.
Pots of dwarf types, from spike emergence
Potassium Rich Fertiliser 11% K
The same 0.5 to 1 g per litre of water every 2 weeks in place of a plain watering. No base feed needed in fresh compost.
After flowering
No feed
Leave the leaves for six weeks and keep watering in a dry September. The corm fills from the leaves, not from the bag.
Signs to watch
Lush leaves and no spike
Nitrogen excess from manure
High-potash only from spike emergence
Corm small and flat at lifting
Lifted too early or leaves cut
Leave six weeks after flowering before lifting
Pests, diseases and problems
Silvery flecks and streaks on leaves and petals, buds brown and fail to open
Gladiolus thrips, worst in hot dry summers; they overwinter on stored corms
Water well in dry spells, as stressed plants suffer most. Burn or bin badly hit top growth at lifting, inspect corms and discard any with rough brown patches, and store the rest cool and dry. Plant early so flowering beats the August peak.
Corms soft, sunken or mouldy in store, or shoots yellow and collapse soon after emerging
Corm rots, including fusarium dry rot and botrytis, carried on damaged or damp corms
Dry corms quickly after lifting, store only firm, clean ones in paper bags with air round them, and plant on a fresh site each year. Never replant a doubtful corm.
Shoot tips eaten off as they come through in spring
Slugs and snails
Go out with a torch on damp evenings, use wool pellets or a grit collar round each group, and apply slug nematodes once the soil is above 5 °C.
Plenty of leaves but no flower spike
Undersized corms, shade, or drought while the spike was forming inside the fan
Buy corms graded 12 cm circumference or larger, give full sun, and soak weekly from the fifth leaf if it is dry.
Spikes bent, kinked or flat on the ground after wind and rain
Shallow planting and no support under a top-heavy spike
Plant 15 cm deep on light soil, put a cane in with each corm and tie in every 30 cm. A bent spike will not straighten, so cut it for the house.
Green or black insects clustered on the spike and buds
Aphids
Rub them off or knock them back with a jet of water before the florets open.
Pruning
Pruning and care
Stake each spike with a cane at planting, tying every 30 cm as it rises; cut spikes for the vase as the bottom floret opens, leaving four leaves to feed the corm. Lift corms in Oct once leaves yellow, cut stems to 2 cm, dry two weeks at 15 to 20 °C, snap off the old shrivelled corm and store in paper bags at 5 to 10 °C.
Good to knowStake the spikes; lift corms before frost in cold gardens. Plant in succession for a long show.
Growing gladioli in pots
Only the dwarf and nanus types, such as 'The Bride', and G. murielae are worth a pot; the tall large-flowered hybrids blow over and look awkward. Plant eight corms 10 cm deep in a 30 cm pot (about 12 litres) of peat-free multipurpose with a fifth grit, and stand it in full sun. Water sparingly until shoots show, then keep it evenly moist and give the liquid potash feed from spike emergence. After flowering let the leaves yellow, then tip the pot out, dry the corms and store them frost free; a pot left outside over winter usually freezes through.
Gladioli: common questions
Do I have to lift gladioli for winter in the UK?
In most of the UK, yes: the large-flowered hybrids are half-hardy and rot or freeze in cold wet soil. Lift in October, dry and store at 5 to 10 °C. In mild southern and coastal gardens on light soil they may survive under a 10 cm mulch, though it is a gamble, and G. communis subsp. byzantinus is hardy and stays in the ground everywhere.
Why are my gladioli falling over?
They were planted too shallow or left unstaked. Set corms 10 to 15 cm deep, deeper on light soil, put a cane in at planting and tie the spike every 30 cm as it rises. Planting in a block rather than a single row also helps them shelter each other.
How long do gladioli take to flower after planting?
About 10 to 12 weeks, a little longer from a cold April planting and a little less from a late May one. That is why planting a batch every fortnight from mid April to May gives flowers from July through September.
Sources
Growing information on this page was checked against these references in November 2026. Feeding rates are Dr Forest label rates.
- How to grow gladioliRHS
- How to grow gladioliBBC Gardeners' World Magazine