Growing Amaryllis

Amaryllis are popular flowering bulbs grown indoors during the winter months. Their  blossoms are spectacular- up to 10 inches across. Flower colors include red, pink, orange, salmon, white, and bicolors. Each bulb will produce one or two stems with two to six blossoms per stem. (One stem with three to four flowers is typical.) The stalks are usually eighteen to thirty inches tall.

Amaryllis are a great way for kids to learn about plants. The bulbs are very large and easy to handle, and they begin to grow soon after planting. Bulbs potted in early November should be in bloom by the middle to end of December.

Forcing Amaryllis

When purchasing amaryllis, select large, solid bulbs that show no sign of shriveling or decay. The largest bulbs often produce 2 flower stalks.

When planting an amaryllis bulb, select a pot that is approximately 1 to 2 inches wider than the diameter of the bulb. The container may be clay, ceramic, or plastic, but should have drainage holes in the bottom. Plant the bulb in good, well-drained potting soil. Add a small amount of potting soil in the bottom of the pot. Center the bulb atop the soil in the middle of the pot. Then add additional potting soil, firming it around the roots and bulb.

When finished potting, the upper one-half of the bulb should remain above the soil surface. Also leave about one inch between the soil surface and the pot’s rim. Water the soil thoroughly with lukewarm water and place in a warm (70° to 75°F) location.

After the initial watering, allow the soil to dry somewhat before watering again. Keep the soil moist, but not wet. Don’t overwater; once per week is usually adequate.

When growth appears, move the plant to a sunny window and apply a water-soluble fertilizer every 2 to 4 weeks. During flower stalk elongation, turn the pot each day to keep the flower stalk growing straight. Flower stalks that lean badly may need staking.

Flowering usually occurs about 6 to 8 weeks after potting. When the amaryllis begins to bloom, move the plant to a slightly cooler (65° to 70°F) location that doesn’t receive direct sun to prolong the life of the flowers.

Care After Flowering

After the flowers fade, use a sharp knife to cut off the flower stalk about one to two inches above the bulb. Be careful not to damage the strap-like foliage. In order for the bulb to bloom again, the plant must replenish its depleted food reserves. The leaves manufacture food for storage in the bulb. Place the plant in a sunny window and water when the soil surface is nearly dry. Fertilize every 2 to 4 weeks with a houseplant fertilizer.

The amaryllis can be moved outdoors in late May or early June. Harden or acclimate the plant to the outdoors by placing it in a shady, protected area for 2 to 3 days then gradually expose it to a few hours of direct sun. Once hardened, select a site in partial to full sun. Dig a hole and set the pot into the ground. Outdoors, continue to water the plant during dry weather. Also, continue to fertilize the amaryllis once or twice a month with a complete analysis soluble plant food through July. Bring the plant indoors in mid-September. Plants left indoors should be kept in a sunny window.

Reflowering of Amaryllis

In order to bloom, amaryllis bulbs must be exposed to temperatures of 50° to 55°F for a minimum of 8 to 10 weeks. This can be accomplished by inducing the plant to go dormant and then storing the dormant bulb at a temperature of 50° to 55°F. To induce dormancy, place the plant in a cool, semi-dark location in late September and withhold water. Cut off the foliage when the leaves turn brown. Then place the dormant bulb in a dark, cool (50° to 55°F) location for at least 8 to 10 weeks.

After the cool requirement has been met, start the growth cycle again by repotting the bulb in fresh soil, watering, and placing it in a well-lit, 70° to 75°F location. Keep the potting soil moist, but not wet, until growth appears.

Another option is to place the plant in a well-lit, 50° to 55°F location in fall. Maintain the amaryllis as a green plant from fall to early to mid-winter. After the cool requirement has been met, move the plant to a warmer (70° to 75°F) location.

This article adapted from Iowa State University Extension Bulletin RG328.

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