Gladiolus
Unlike many bulbs in this KB, this genus is not reliably hardy left in the ground through a typical UK winter — treat it like a half-hardy summer bulb (lift, dry, and store) unless gardening in an unusually sheltered, mild spot.
Care
Needs a warm, sunny, sheltered spot for the strongest flower spikes.
Regular watering through the growing season, especially in dry spells while the flower spike is developing.
Free-draining, fertile soil; heavy or waterlogged soil is the main cause of corm rot.
Deadhead individual flowers as they fade along the spike; cut the whole flower stem down once flowering finishes, but leave the foliage to die back naturally to recharge the corm.
Feed with a high-potash liquid feed from when the flower spike is forming until it opens. Avoid nitrogen-rich feeds: they give soft leaves and a spike that needs staking even in a sheltered spot.
Lift the corms after the first frost blackens the foliage and separate the cormlets clustered round the base of the new corm; grown on they flower in two or three years. Store the corms dry and frost-free over winter.
Month by month
Months change with the climate: in southern Italy tomatoes go out two months earlier than in England.
- AprilPlant corms from mid-spring once the risk of hard frost has passed, in succession every couple of weeks for a longer flowering season.
- JuneStake tall spikes as flower buds develop, especially in an exposed spot — top-heavy spikes snap easily in wind. how ›
- OctoberIn most of the UK, lift corms once the foliage has died back and store somewhere cool, dry and frost-free over winter — this genus is not reliably hardy left in the ground. how ›
Months based on climate: UK. Your choice stays on this device.
- MarchPlant corms from mid-spring once the risk of hard frost has passed, in succession every couple of weeks for a longer flowering season.
- JuneStake tall spikes as flower buds develop, especially in an exposed spot — top-heavy spikes snap easily in wind. how ›
- OctoberIn most of the UK, lift corms once the foliage has died back and store somewhere cool, dry and frost-free over winter — this genus is not reliably hardy left in the ground. how ›
Months based on climate: Northern Italy. Your choice stays on this device.
- MarchPlant corms from mid-spring once the risk of hard frost has passed, in succession every couple of weeks for a longer flowering season.
- JuneStake tall spikes as flower buds develop, especially in an exposed spot — top-heavy spikes snap easily in wind. how ›
- NovemberIn most of the UK, lift corms once the foliage has died back and store somewhere cool, dry and frost-free over winter — this genus is not reliably hardy left in the ground. how ›
Months based on climate: Central Italy. Your choice stays on this device.
- FebruaryPlant corms from mid-spring once the risk of hard frost has passed, in succession every couple of weeks for a longer flowering season.
- JuneStake tall spikes as flower buds develop, especially in an exposed spot — top-heavy spikes snap easily in wind. how ›
- NovemberIn most of the UK, lift corms once the foliage has died back and store somewhere cool, dry and frost-free over winter — this genus is not reliably hardy left in the ground. how ›
Months based on climate: Southern Italy and islands. Your choice stays on this device.
Common problems
How to spot it. Corms rot or fail to reappear the following year if left in the ground.
What to do. Not reliably hardy through a UK winter in most gardens — lift and store corms somewhere cool, dry and frost-free instead of leaving them in the ground, unless in a particularly mild, sheltered garden.
How to spot it. Top-heavy stems broken or leaning after wind or rain.
What to do. Stake spikes early, as soon as buds start to develop, rather than after damage occurs.
How to spot it. Silvery streaking or distorted, discoloured flowers.
What to do. Common on this genus, especially in a hot, dry summer — remove and dispose of badly affected flowers; generally more disfiguring than seriously harmful.
Questions
Gladiolus: is it hardy?
H3: Half hardy. It survives down to −5 °C.
Can it grow in a pot?
Grows well in a deep pot, and containers make lifting the corms for winter storage considerably easier than digging them out of a border.
Gladiolus: when do you prune it?
Deadhead individual flowers as they fade along the spike; cut the whole flower stem down once flowering finishes, but leave the foliage to die back naturally to recharge the corm.
Gladiolus: when does it flower?
In the climate of UK it flowers in July–September.
When do you feed it?
Feed with a high-potash liquid feed from when the flower spike is forming until it opens. Avoid nitrogen-rich feeds: they give soft leaves and a spike that needs staking even in a sheltered spot. Feeding months, UK: May–July.