How to grow gladioli and the best varieties

A great flower for cutting for vases, bright gladioli blooms look spectacular in summer bouquets. However, they can be tricky to grow with their tendency to flop, and the buds don’t always open all the way to the top of the flower spike, making a disappointing display.

Which? Gardening magazine trialled a range of gladioli to find the very best varieties that will give a bright show of flowers on sturdy stems that will make a great plant for the border or for cutting. 

We show you how to plant the corms in spring in borders or as cut flowers in your veg patch.

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Key facts

PLANT TYPE Summer-flowering bulb

POSITION Full sun

SOIL Well-drained, fertile

How to grow gladioli: month by month

Full testing results for gladioli

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Caring for your plants

Planting gladioli corms

Check that the corms are healthy, firm and plump before planting. 

At the end of April or beginning of May, plant into well-drained soil in a sunny position 15-20cm deep and 15cm apart.

Help your plants with a recommended soil improver.

Caring for gladioli

Water well during dry spells and weed regularly. 

Feed with a high-potash fertiliser, such as tomato food, once flower spikes appear. 

Stake using bamboo canes and string. Tie the stems at intervals along their length, so that they don’t bend from the tied point.

Make things easier with a Best Buy watering can.

Common gladioli problems 

Thrips can damage leaves and flowers. Treat with contact insecticide if infestations get severe. 

Viruses can cause the leaves to turn streaky and yellow, and affect flowering. Destroy any affected corms. 

Identify your plants with Best Buy plastic-free labels.

What to do with gladioli corms after flowering

Gladioli can survive outside in mild areas if the soil is well drained and they’re mulched. However, they will flower better if lifted and stored inside over winter. 

Allow the corms to dry fully, then remove the leaves and keep frost-free, disposing of any that show signs of rotting.

How we test gladioli

We chose 23 easily available varieties, including a range of bright and subtler colours, as well as different bloom sizes. Unfortunately, four varieties either didn’t emerge or didn’t produce any flower spikes. At the end of April, we planted 20 corms of each variety into a well-drained, sunny bed at our Capel Manor College trial site in north London, and kept them well watered using trickle irrigation. 

We assessed the plants weekly from when the first flower spikes appeared, for their impact (including how many flowers were out at once on a stem) and whether they were flopping and needed to be staked.