The familiar "Dutch hybrid amaryllis", actually hybrids in the genus Hippeastrum, are often a challenge to bring to bloom in later years. the Dutch, the South Africans, and the Indians have made a science of preparing mature amaryllis bulbs for the market. They are ready to bloom when they reach the shops.

Having one of these magnificent bulbs bloom for you again in later years is another matter. You will have to pay attention to some of the fundamentals of plant culture to succeed: light, heat, and feeding

Light

Amaryllis will need plenty of light to rebuild their strength and build a new bloom scape (stalk). They just about have to be outdoors in full sun or very light shade during the growing sseason. They should be there from just after the last frost of Spring until just before the first frost of autumn. A sunny, south-facing windowsill would be the minimum light exposure necessary to produce future flowers.

Heat

There are two periods when the temperatures are important for the development of new blooms in an amaryllis:

• During dormant storage, or the autumn resting period, the temperatures can be cool but should never fall below about 60° F (15° C).
    
  
• When coming back into growth after the resting period, the temperatures should be warm, at least 75° F (24° C), and 80° F (27° C) would be better. This promotes development of new roots and brings the bulb back into active growth.
    
  

Feeding

It takes plenty of food to rebuild the big flowers of an amaryllis. Without this, there is going to be little or no subsequent bloom after that first year following purchase.

Bulbs generally need a fertilizer high in nitrogen (N), low in phosphate (P), and high in potassium (K, "potash"). Compositions like 10-5-10 or 20-10-20 would be suitable for most bulbs. Amaryllis are no exception to this rule.

Organic fertilizers that can promote the growth of bacteria or fungi are to be avoided. The roots and bulbs of amaryllis are susceptible to bacterial and fungal rots. Conditions supporting growth of bacteria or fungi are likely to cause rotting of the bulb and roots of an amaryllis.

Other Matters

Potting mix can be very important too. The medium should be free-draining, so that watering and feeding do not result in stagnent conditions around the roots. They can easily drown in a soggy growth medium.

Repotting need not be done every year, but must be done occasionally. It is good to periodically remove the dead roots that accumulate in the pot. The bulb should sit high in the potting medium, at least half exposed.

We hope these guidelines will aid you in bringing your amaryllis bulbs back into bloom for many years.

Jim Shields
SHIELDS GARDENS LTD.

Other Sources of Information

Bulbs for Warm Climates, by Thad M. Howard, University of Texas Press, Austin (2001).
Bulbs, Revised Edition, by John E. Bryan, Timber Press, Portland (2002).
RHS Manual of Bulbs, John Bryan and Mark Griffiths, Eds., Timber Press (1995).