Care and Cultivation of Summer-flowering Bulbs and Tubers

When you receive your new bulbs and tubers,  unpack and check them immediately to ensure they are what you ordered and in the condition you’d expect.


Bulbs/tubers that are not planted at once should be stored in a cool, dry but reliably frost-free place until planting time. Any showing signs of growth are best placed upright in a tray of dry peat or vermiculite so that the developing shoots will grow upright.

Before planting any bulbs/tubers in the garden, dig over the ground thoroughly, removing any perennial weeds. At the same time enrich it by incorporating plenty of well-rotted manure, compost or leafmould and a dressing of bone meal. Most bulbs are intolerant of poor drainage so, if your soil is heavy, also dig in plenty of sharp sand or horticultural grit. Always try to plant in mild weather and avoid periods when the ground is very cold or wet.

Summer-flowering bulbs/tubers permanently planted out in the garden also enjoy an annual dressing of slow-release fertiliser in spring. Most bulbs benefit from deadheading after flowering, unless you wish to save seed or retain ornamental seed heads.  To prevent cultivation damage to dormant bulbs, mark their positions with sticks when the foliage dies down.

Protect all bulbs/tubers from slug damage, taking particular care of the vulnerable young growth.

Growing Bulbs and Tubers in Pots 

dahlias from Mr Fothergill'sUnless stated otherwise, plant bulbs at about twice their own depth in a loam-based compost. John Innes No 2 with 20-25% extra sharp sand is generally suitable. Under glass keep them in good light, but with shade from the hottest sun, and, when in growth, keep well watered and ventilate as much as possible at all times.

When they are actively growing, feed potted bulbs about every 2-3 weeks with a high potash fertiliser, such as is sold for tomatoes. Alternatively, add some slow-release fertiliser to the compost at potting or repotting time. Repot annually at the end of the dormant period and either replace the compost completely or scrape away the surface down to the level of the bulbs and refill with new potting soil. 

Growing Bulbs and Tubers in the Garden

– Plant at approximately three times the depth of the bulb in well-drained soil and full sun. Allium will tolerate partial shade but perform best in full sun. Space them 10-12cm (4-5in) apart. Divide clumps in the autumn and do not water when plants are dormant.  Caution: Contact with the bulbs may irritate skin or aggravate skin allergies.

Begonia – Start off indoors, in pots in early March then plant out in late May. Space them 20-30cm (8-12in) apart. Plant where the light is good but there is light shade or, at least, shade during the hottest part of the day. Keep well watered in dry weather and feed regularly with a balanced liquid fertiliser. Can be overwintered, lift before the first frosts in Autumn.

Dahlias from Mr Fothergill'sDahlia – Set out tubers, spacing them 60cm (2ft) apart and with the crown about 5-7cm (2-3in) below soil level. Water well in dry weather and mulch with well-rotted compost or manure to keep down weeds. Feed regularly, using a high nitrogen liquid fertiliser while plants are developing and change to a tomato type fertiliser during the main flowering period. Tie plants to their stakes as they develop and dead-head regularly to prolong flowering.

Freesia – Plant in full sun in well-drained soil. Space them10-15cm (4-6 in) apart at a depth of 4-5cm. When in flower feed weekly. Can be overwintered, lift before the first frosts in Autumn.

Gladiolus – Gladiolus require an open sunny position in a well-drained soil. Plant in groups 10-15cm (4-6in) apart and 10-15cm (4-6in) deep. The lighter the soil, the deeper they should be planted, ensuring the base of the corm sits firmly in the bottom of the hole.

Sparaxis – Plant in full sun in a neutral or alkaline soil. Spraxis will tolerate dry soil. Space them 10-15cm (4-6in) apart. Plant 7-8cm deep on a small amount of sand if possible. Once in flower feed and water regularly. In exposed areas you may need to provide a little support.


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