Issue: December 30, 1996

Amaryllis

What can I do to make my amaryllis bloom? It doesn't die, but it hasn't bloomed for several years.

The amaryllis needs good growth followed by a rest period before it will flower. If it is grown indoors with insufficient light during the summer, it cannot develop flowers. If it needs repotting and the soil is deficient in nutrients, especially phosphorus, it won't bloom. If it is kept in a growing mode and not allowed to rest, it won't bloom.

So, give it plenty of light during the growing season, May through August. It doesn't need full sunlight, especially here in New Mexico, but a bright shade with dappled sunlight is beneficial. It is too dark under some trees; if grass doesn't grow well under a tree, there is probably too little light for the amaryllis.

The amaryllis needs very well-drained soil, but this soil should not be allowed to dry completely between waterings during the growing season. Check the hole at the bottom of the pot and be sure it is not bone dry before watering. However, don't water so often that the soil stays soggy. A potting soil containing a lot of sand, perlite, or other aeration material will help keep the soil from becoming too soggy.

Every few years the amaryllis should be repotted. Don't use a pot that is much larger than the bulb. One-half to one inch between the bulb and the edge of the pot is sufficient. The calcium in most of our New Mexico water accumulates in the potting soil and interferes with the uptake of phosphorus and other nutrients that the amaryllis needs. Repotting and carefully changing the soil while minimizing the damage to roots will help. Repotting should be done during the dormant season, the autumn.

During the growing season, fertilize every second or third watering with a "flowering houseplant" type of fertilizer. This type of fertilizer has higher levels of phosphorus which encourages good flower development. Don't apply the fertilizer any stronger than the label recommends.

In early September, reduce watering and allow the foliage to die back. This begins the rest period during which the flowers are formed. Don't fertilize again until leaves appear in the spring. While the pots should not be allowed to become bone-dry, less water is needed and overwatering should definitely be avoided. Cool temperatures in the fall, 55 to 60 degrees, helps the amaryllis develop its flowers. Do not let the pots freeze. Without any extra effort on your part, the flower stalk will appear when the bulb is ready. At this time, increase the watering slightly. If you wish to speed the development of the flowers, you can raise the temperature slightly.

Leaves will have developed by the time the flower stalk is matured and the flowers have opened. When the leaves begin growing, gradually increase to watering levels you use during the growing season. After flowering, remove the flower stalk and begin fertilizing.

Enjoy the flowers.

Marisa Y. Thompson, PhD, is the Extension Horticulture Specialist, in the Department of Extension Plant Sciences at the New Mexico State University Los Lunas Agricultural Science Center, email: desertblooms@nmsu.edu, office: 505-865-7340, ext. 113.

For more gardening information, visit the NMSU Extension Horticulture page at Desert Blooms and the NMSU Horticulture Publications page.

Send gardening questions to Southwest Yard and Garden - Attn: Dr. Marisa Thompson at desertblooms@nmsu.edu, or at the Desert Blooms Facebook.

Please copy your County Extension Agent and indicate your county of residence when you submit your question!