When to Fertilize an Amaryllis

Soil

• Amaryllis bulbs don't require highly fertile soil. Use sterile potting soil that is rich in organic matter, such as peat, for pot-grown amaryllis. The organic matter isn't for nutrition. Instead it ensures that the pot retains the proper amount of moisture. Bedding plants must be grown in well-drained beds. Use compost in beds to help improve the drainage and quality. Compost has trace amounts of nutrients but use additional fertilizer.

During Flowering

• Begin fertilizing the amaryllis bulb only after you notice new growth and the plant produces its first leaves. Fertilizing dormant bulbs can damage or kill the amaryllis. Feed the potted bulbs twice monthly with a soluble fertilizer formulated for flowering plants. These fertilizers have a high amount of phosphorus and are labeled with a ratio of 5-10-5 or similar. Use 1 lb. of 5-10-10 analysis fertilizer per every 100 square feet of garden bed for outdoor amaryllis. Apply the fertilizer to the beds as soon as the plants produce leaves, then reapply once the stems are 8 inches tall.

After Flowering

• Once flowering completes keep the amaryllis well-fed so the plant can collect the necessary energy for the next year's flowering period. Continue to fertilize potted amaryllis every two weeks with the soluble fertilizer. Fertilize bedding plants immediately after the last flowers wither, using the same amount and type of fertilizer used at earlier feedings.

Forcing Dormancy

• The amaryllis plant must go through a dormant period if it's to rebloom at the desired time. Stop all fertilizer treatments 12 weeks before you desire the plant to resume flowering. Gradually reduce watering until the foliage dies back. Allow the bulb to rest for eight to 12 weeks before resuming watering and regular fertilization. Garden-grown amaryllis are rarely forced into bloom, so apply fertilizer at the three recommended times per year beginning when the first leaves are produced each spring.