Some of the most popular house plants are grown from tender bulbs. By keeping to their natural cycle of rest and growth, you’ll get colourful blooms year after year. By choosing carefully, you can have tender bulbous house plants in flower all year round. On the patio, tender bulbs add late summer and autumn colour, to follow the early summer colour of herbaceous perennials.
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How bulbs work
Bulbs store food and water during a plant’s active growth, so it can survive a long period of rest, or dormancy. If you feed and water a bulb all year round, you’re not being kind but preventing dormancy and harming the plant.
The annual cycle usually consists of growing leaves, flowering, dying back, resting and starting up again. Exceptions include Hippeastrum and Nerine flexuosa, which flower before leaves appear; and Scarborough Lily and some Haemanthus, which are evergreen.
Not all bulbs grown as house plants are tender— plants such as Hyacinth, Tulip and Daffodil are grown from hardy bulbs. If you have bulbs of which you are unsure, check with a nursery.
Potting and repotting
The best time to pot dormant bulbs varies from plant to plant, and also according to whether natural or forced flowering is wanted. Pot up specially prepared Christmas-flowering Hippeastrum in early November; in December, for flowers in late winter; and in February, for flowers in spring. Pot Cape Cowslip, Nerine flexuosa and Scarborough Lily in summer, most Haemanthus in spring, Sprekelia in February, and Easter Lily and Forest Lily in autumn.
Use a soil-based potting mixture, and pots just large enough to hold the bulb. For large bulbs, such as Hippeastrum, use a 12.5-15cm (5—bin) pot. For small bulbs, such as Cape Cowslip, plant 5 or 6 in a 12.5cm (5in) pot.
Haemanthus, Sprekelia, Cape Cowslip, Nerine flexuosa and Scarborough Lily like their ‘necks’ above the potting mixture. Leave the top half of Hippeastrum and Forest Lily bulbs exposed. Cover Easter Lilies with 5cm (2in) of potting mixture, and keep dark, cold and just moist until growth appears.
Most bulbs flower best when slightly pot-bound, so repot every 3-4 years. Between repottings, top-dress Hippeastrum and Haemanthus when starting into growth. Carefully scrape away the top 1.5cm (1/2in) of potting mixture, and replace with fresh.
Watering
Bulbs never like being waterlogged, even in full growth. Let the potting mixture dry out a little between waterings, but give Easter Lily, Forest Lily and Cape Cowslip steadily moist potting mixture. Use tepid, not cold, water. After flowering, water moderately until the leaves start to turn yellow, then gradually reduce watering. During dormancy, water very sparingly—just enough to keep the bulb from shrivelling. Evergreen bulbs need a bit more water when resting, and keep Forest Lily bone-dry. To start bulbs into growth, water sparingly until growth is well under way, then gradually increase the watering.
Feeding
Feed most bulbs every 2 weeks when actively growing. Start 2 weeks after the first full watering, and continue until after flowering, then switch to a potash-high fertilizer for 6-8 weeks, or until the leaves start to die back. Start feeding Hippeastrum after flowering and continue feeding until the autumn.
Propagating bulbs
Most bulbs naturally produce offsets, or bulblets. These emerge from around the base of the mother bulb and gradually become small bulbs. The easiest way to make more plants is to remove the bulblets when repotting, and pot them up separately. Treat as you would the mother plant, but it may take a couple of years for the bulblets to reach flowering size. This is still quicker than raising from seed, which can take up to five years.
Planting bulbs
Cover Easter Lily hulk with 5cm (2in) of compost. Hippeastrum and Forest Lilies like to be half-exposed, while Cape Cowslip, and Scarborough Lily like only their necks exposed.
Potting large bulbs
To flesh out shrivelled roots of Hippeastrum, soak them overnight in a shallow dish of water. This will also help to promote growth in the bulb. Plant a Hippeastrum bulb in soil-based compost in a pot just large enough for it. Provide broken pot rubble in the base of the pot for good drainage.
Bulbs to consider
Summer
- Forest Lily ( Veltheimia)
- Nerine (Nerine flexuo.sa)
- Amaryllis
- Easter Lily (Lillian longi(larion)
- Guernsey Lily (Nerine surniensis)
- Pineapple Flower
- Sea Lily (Ptincratilim)
- Spider Lily
- Sprekelia
- Summer Hyacinth (Cialtonia)
Winter
- Cape Cowslip (Lachenalia)
Spring
- Cape Cowslip
- Easter Lily (Lilium longillorum)
- Forest Lily (Veltheimia) Haemanthus Hippeastrum
Autumn
- Haemanthus
- Scarborough Lily (Valium)
- Summer
- Easter Lily
- Scarborough Lily
Haemanthus, or Blood Lily, can be made to flower between spring and autumn. It must be grown from seed.
The very popular Narcissus can be propagated by rooting the bulbs either on moist pebbles or in potting compost.
I managed to keep my Easter Lily alive, but the second year’s flowers were disappointingly small. What did I do wrong?
Nothing. It is better to discard or plant Easter Lilies in the garden after forcing, as they can’t be forced again.
My friend’s hippeastrum flowers much earlier than mine everyyear. Why?
The warmer the room, the earlier you can start it into growth. For Christmas flowering, 21°C (70°F) is needed; for late winter flowering, 13°C (55°F); and for spring flowering, 10°C (50°F).
