Backyard Gardening

By Debra Burrows, PhD

At this time of year, it’s not uncommon to see Amaryllis bulbs sold as holiday gifts.  In fact, they seem to be everywhere.  There’s something especially appealing about a colorful, blooming plant during the cold, dark days of winter.  Amaryllis bulbs do not disappoint in that respect.  When potted and placed on a sunny windowsill, the bulbs, often three to five inches in diameter, send up tall flower stalks (scapes) that produce large, trumpet-shaped flowers in a variety of colors.  

Native to tropical and sub-tropical regions of South America, Amaryllis (Hippeastrum spp.) are grown primarily as houseplants in much of the United States, although some varieties, such as Hippeastrum x johnsonii, can be planted outdoors in USDA Hardiness zones 7 and above.  I experienced this first-hand on a trip to Hawaii, where, much to my surprise, I saw Amaryllis blooming beneath trees in an orchard.

Amaryllis bred for use as houseplants can be found in shades of red, pink, orange, salmon, and white.  Bi-colors, as well as both single and double flowering selections are available.  The flowers are particularly impressive, ranging in size from four to ten inches.  They are borne atop strong scapes that can reach as much as three feet tall depending upon variety. Most varieties produce scapes in the 18” to 24” range.  They usually emerge from the bulb first followed by long, strap-like leaves.  

Given the right conditions, Amaryllis bulbs can bloom and thrive for many years.  Growing them successfully begins with purchasing healthy bulbs.  They should be firm to the touch and show no signs of bruising or mold.  Larger bulbs tend to produce more flowers.  

Dormant bulbs should be planted in containers that are between one and two inches wider than the widest portion of the bulb, but not larger.  Unlike many houseplants, Amaryllis prefer to be somewhat “pot-bound”.  The height of the container should be approximately twice the height of the bulb to allow room for root growth below the bulb. Drainage holes are essential.  Containers can be either plastic or clay.  Because Amaryllis become quite tall, a clay pot, because of its weight, is less likely to tip over as the plant grows.  Plastic pots can be placed inside decorative containers or larger pots to add stability, so long as they don’t impede drainage.  

Amaryllis bulbs should be planted so that ½ to 1/3 of the bulb remains above the soil level.  With that in mind, add potting soil to the pot and gently tamp it down.  Place the bulb on top and check to see that the required ½ to 1/3 of the bulb will be above the soil level surface when additional potting soil is added.  Add the additional potting soil and tamp lightly. Water thoroughly and allow the pot to drain freely.  Soil that has too much moisture can cause bulb rot.  Do not add fertilizer.  Fertilizer at this stage can cause root damage.  Place the potted bulb in an empty saucer on a sunny windowsill where it will receive bright light throughout the day and at least four hours of direct sunlight.  Water only when the top 1”- 2” of the potting mix feels dry and never let the pot sit in water.  Scapes and leaves will grow toward the sunlight, so rotate the pot weekly to encourage even growth.   After scapes and leaves emerge, fertilize weekly using an indoor plant food recommended for use with flowering plants. Follow label directions and be careful not to over-fertilize.  When the plant is flowering, watering can be increased to keep the potting mix evenly moist, but definitely not soggy or wet.  

Proper care of the Amaryllis plant after it has flowered is key to its ability to bloom the following year.  The plant must remain in active growth in order to store enough energy in the bulb to produce both flowers and leaves in the next growing season. When flowers have faded, remove them by cutting off at the top of the flower stalk (scape).  Do not remove the entire flower stalk.  It will continue to photosynthesize and feed the bulb until it turns yellow.  When it yellows, it can be removed by cutting it off about two inches above the bulb.  Keep the plant in a bright sunny location and continue to fertilize it.  This allows the leaves to go on feeding the plant so that it can store energy in the bulb for the following year.  After danger of frost, the potted Amaryllis can be placed outside for the summer months.  Begin by placing it in an area of dappled sunlight to allow it to acclimate.  After a few weeks, select a sunny location and sink the entire pot into the ground so that it is even with the soil surface.  

Prior to the first frost, dig up the pot and place it in a cool dark location that does not get below freezing to allow the plant to become dormant.  Do not water during this period.  I’ve done this with my Amaryllis plants for many years and it has worked very well.  I place them on a shelf in my garage and let them dry out.  After the leaves have shriveled and dried, I remove them and examine the plant to determine if repotting is necessary.  Oftentimes I’ll find that the plant has grown a bulblet alongside the main bulb so I remove both from the pot and repot them separately.  I usually initiate the dormant period in October and begin repotting in December to allow the bulb to rest for six to eight weeks.  Because plants usually bloom about six weeks after coming out of dormancy, that means that they will flower in February, a time when their beauty and color are most welcome.

Debra Burrows, PhD is a retired Penn State Extension Educator and a certified Master Gardener.  She can be reached at dcb3@psu.edu.