Bulb Growing Guide - Summer Flowering

Summer flowering bulbs need to be planted in spring and, together with spring bedding, they make a
colourful display. Summer bulbs require very little care, many can simply be planted in spring allowing you to sit back and wait to enjoy the rewards in the warmer months year after year!

Planting
Early spring is the time to think about planting summer bulbs and bulb-like structures like lily bulbs, begonia and gladioli corms, and dahlia tubers. They will start to grow stems and leaves through spring and burst into flower in summer. Choose from a rich variety of colours, sizes and textures.

Receiving your bulbs when they arrive in spring
Your bulbs should be planted straight away on arrival. For best results, we recommend growing begonia corms on in containers indoors until risk of frost has passed (usually late May), after which, they can then be re-planted or positioned outside. Lilies, dahlias and gladioli should be planted straight outside unless the ground is waterlogged or frozen, however it’s best to protect the young growth with mulch or fleece until risk of frost has passed.

Growing bulbs straight into the ground
Bulbs prefer free-draining soil. For best results dig in some coarse sand or grit before planting to aid drainage if soil is heavy or compacted. To give your plants an extra boost and to maximise flowering, rake some fish, blood and bone or Organic Extra dry Farmyard Manure into the surface of the soil before planting.

Lily bulbs and gladioli corms:
Dig a hole with a trowel 2 – 3 times the depth of the bulb. Loosen the soil at the bottom of the hole.
Position the bulb at the bottom of the hole in an upright position (with the pointed end facing upwards) and backfill the soil. Firm down the soil with your hands and water-in.
Spacing: Allow about 20cm (8 in) between bulbs. Some Lilies require support to stop them falling over particularly Skyscraper types.

Dahlia tubers:
The tuber should be planted horizontally with the old stem at the top, so dig a hole that’s wide enough to accommodate it and about 12cm (5 ½ in) deep. Loosen the soil at the bottom of the hole. If your soil is very heavy or clay, mix in a good handful of grit or sand too. Position the tuber at the bottom of the hole. Position the bulb with any visible buds pointing upwards. Backfill the hole and firm down with your hands. Water thoroughly after planting.
Spacing: Allow about 40cm (16 in) between tubers.

Begonia corms:
Begonias are best started in containers indoors as they are tender and need a longer growing period.
Plant the corms close to the surface ensure the bulb is position the right way up. Cover the corm with a fine layer of soil – the edges of the corm should only just be visible.
Spacing: Allow about 30cm (12 in) between corms.

Growing bulbs and bulb-like structures in containers
Place broken crocks or polystyrene in the base of the pot. Half fill with compost and place bulbs on top. Add crocks intermittently in the soil for even better drainage but take care of hidden sharp edges and wear gloves when emptying pots at a later date. Cover bulbs, firm compost gently, and water well.
If using Begonias plant the corms close to the surface with the concave side pointing upwards. Loosen the soil at the bottom of the hole. If your soil is very heavy or clay, mix in a good handful of grit or sand too. Position the bulb at the bottom of the hole in an upright position (with the pointed end facing upwards) and backfill the soil. Firm down the soil with your hands and water-in. Allow about 20cm (8 in) between bulbs.

In autumn after flowering you can leave some summer bulbs in the ground over winter with a bit of protection, or you can lift up the bulbs/tubers/ corms and store in a cool, dry place. If leaving in the ground, the bulbs will need to have their crowns covered with a thick mulch of peat, compost or leaf mould. If lifting and storing in winter indoors (recommended for begonias and dahlias due to our unpredictable winters.) The best time to do this is when the foliage has died down: cut the foliage back to 3cm (1- 1 ½ in) above the soil surface and dig up the tubers or corms with a garden fork. Shake off excess soil and store in a light, frost free place over winter, in a wooden crate or cardboard box, submerged in dry compost is ideal. 

After Flowering
Not all summer bulbs are fully hardy. After flowering, but before the weather turns really cold, those of a more tender nature will need to have their crowns covered with a thick mulch of peat, compost or leaf mould. Alternatively, some plants (particularly Dahlias and Begonias) should be lifted and stored for the winter. The best time to do this is when the foliage has died down: cut the foliage back to 1” above the soil surface and dig up the tubers or corms with a garden fork. Shake off excess soil and store in a light, frost free place over winter, in a wooden crate or cardboard box, submerged in dry compost is ideal.

NB - There’s no need to water bulbs, tubers or corms when in storage as this may cause the bulbs to rot.