The greenhouse bulbous plant often called amaryllis is correctly known horticulturally and botanically as Hippeastrum. The plants in cultivation are hybrids. The true Amaryllis is a slightly tender, bulbous plant, Amaryllis belladonna, which is normally grown out of doors in a well-drained border against a warm sunny wall.
Planting
Pot up newly purchased bulbs from October to January - large bulbs in 15cm (6in) pots, smaller ones in 10cm (4in) pots - planting so that two-thirds of the bulb remains above the surface and water in well. John Innes No. 2 compost is a suitable medium. Water sparingly until the onset of new leaves growth and then start watering regularly. Place in a well lit spot, temperature of 21°C (70°F) is ideal. Do not let the compost dry out as this can slow the initial growth. Water from the top using tepid water avoiding wetting the top of the bulb. Should excess water collect in the saucer, tip it out. Excess watering could cause rotting of the bulb.
You can aid rooting by soaking the dried up roots for 12-24 hours prior to planting, by positioning it over a container with water, but keeping the base of the bulb dry.
As soon as the new leaves and/or flower shoot reach 5cm (2in) apply balanced liquid fertiliser every two weeks. Turn the pot around a little every day to prevent the flower stalk (scape) growing towards light and becoming bent and possibly breaking. Hybrids with tall stalks and large flowers should be staked when the stalk reaches about 40cm (16in) to prevent it from collapsing. When the flowers begin to open, move the plant to a cooler place, about 15–18°C (59-64°F), to extend the flowering period.
The bulb should flower within six to eight weeks after planting. Sometimes the flowering stem will appear before, or be accompanied by, the strap-like leaves. The flowering period is from January to May.
Aftercare
After flowering, if possible, let the flowers and flower stalk die down naturally and then remove. Grow the bulb on, continue watering and apply a balanced liquid fertiliser weekly. You can place the bulbs in their pots outside or in the greenhouse during the summer months. Make sure that the plants do not dry out, mist around the leaves, avoid prolonged periods of direct sunshine and temperatures above 30°C (86°F). Slugs and snails may be a major problem. Remove only diseased or damaged leaves.
A cool period is required for the bulbs to flower well. In mid October move the plants to a well lit position and maintain temperature of 13°C (39°F) for 8-10 weeks, do not let the temperature drop below 5°C (41°F). Stop feeding and reduce watering. Some of the foliage may start dying back.
Alternatively, in late September withhold watering and let the plants gradually dry out. Still in their pots, they can then be laid on their sides in a cool place such as a greenhouse/garage one or two months. This is induced dormancy, although with some plants the foliage will naturally begin die down in July.
After the cool/dormant period, cut the remaining old leaves to 10cm (4in)from the neck of the bulb. Replace the top 2.5 - 5cm (1-2in) of soil with fresh one. Repotting is only necessary every two to three years. Commence growing as for after planting of a new bulb.
Propagation
Sow seeds as fresh as possible in March or April. Maintain a temperature of 21°C (70°F). Seeds can be started in John Innes seed compost and seedlings potted on using John Innes No 2 with the addition of extra sharp sand or grit. Grow in individual small pots, potting on periodically during the spring-summer season into slightly larger pots as the young plants develop. Keep plants growing actively, in moderate warmth, without inducing dormancy. Emerging offsets may already have their own roots. They can be separated when repotting (January – March) and potted up individually. Keep at a temperature of 21°C (70°F) and treat in same way as potted seedling. Propagation by offset will produce a flowering bulb in three to four years.
Begin feeding seedlings with a general purpose pot-plant feed, five to six weeks after germination and continue until September.
If foliage is retained during the winter, feed occasionally at seven to eight week intervals with balanced or high potash feed at half strength, withholding feed for the first five to six weeks after repotting. It will take up to six years for the bulbs to reach maturity and flower.
Failure to Flower
Failure to flower can be due to drying off bulbs too early, growing in shady conditions or underwatering during the previous summer. Attack from pests such as bulb scale mite, large narcissus bulb fly or various fungal diseases might be also to blame.
Further information
For further reading see RHS Plant Collectors Guide Hippeastrum the gardener’s amaryllis, ISBN 0-88192-639-6, by Veronica M. Read, who is the National Plant Collection Holder of Hippeastrum.