Amaryllis Tips and Troubleshooting

Poinsettias are okay—now available in orange, blue, purple, and sprinkled with glitter! I like the occasional Thanksgiving or Christmas cactus (Schlumbergia spp.), but I cannot seem to get enough of Amaryllis (Hippeastrum).

If you are like me, you buy the bulbs as soon as they are in the stores, pot them up, and have high hopes of bringing them back into flower year after year. Sometimes, I actually succeed.

What does it take to be successful in growing larger and larger Amaryllis year after year? Predictably, the critical element is sun and plenty of it.

However, selection does play a role. The hybrid Hippeastrum that are offered in many retail establishments in the fall are presented in various forms. You can buy the ubiquitous bulb-in-a-box, bulbs coated with a thick and decorative wax, or loose bulbs. You want to buy the bulb of the greatest circumference, if both display and growing on are your goals. The larger the bulb, the more flower stalks and leaves. Remember that this is a sub-tropical or tropical plant, so don’t ever allow it to get cold by leaving it in the car or garage.

For best growing results, use a pot that is about 2" in diameter larger than the bulb. Use a well-drained potting medium and place the bulb so the top one-third of the bulb is above the soil line. Place it in a window that gets several hours of direct sun and water it in well. Do not water again until the bulb initiates roots. Once there are roots, water as needed, allowing the top ¼" of the medium to dry out between waterings. The watering interval will depend on the plant’s rate of growth and the amount of sun it is getting. Do not water based on your weekly chore schedule.

Amaryllis

Photo by Kathy Jentz, Washington Gardener Magazine

Flower stalks emerge depending on the temperature and genetics of the hybrid. Often, when the fall weather is warm, bloom stalk initiation occurs in the store where you buy your bulbs. Pot them up immediately, if that is the case. You will probably need to stake the flower stalk, since the bulb has not put out roots to stabilize it in the pot.

After the bloom stalk has faded, cut it back close to the top of the bulb. Make sure the plant is in several hours of direct sun at this point. The emerging leaves will get very long and weak if the plant is not getting enough sun. The plant’s leaf growth over the next six months or so will replenish the bulb and will ensure flowering stalks next year. The leaves grow long and floppy, so they may need staking at this point.

I find I have the best return in bloom stalks if I put the plants outside in mid-May. I acclimate the plants to the increased light and grow them in partsun/part-shade. In most climates, they will need to receive about five hours of direct sun. I often take the bulb out of the pot and plant it directly in a prepared bed. I have fewer small pots to water in the summer’s heat that way and the bulbs have plenty of room to grow.

It is a fallacy that they need confined roots to bloom well. Our modern-day hybrids are bred from South American species, so they thrive in heat and humidity.

At some point in the late summer or early fall, the plant will need to go dormant. Before the first frost, I lift those in the bed and bring the potted ones into a cool protected area to dry off and go dormant. Turn pots on their side to make sure they don’t accidentally get watered. You want to keep them at temperatures of 45–50° F for 6–10 weeks or until the bulb shows signs of growing again.

When will they bloom? Depends on the hybrid and its genetics. I find they often prefer to bloom in the early spring indoors and I have had bulbs bloom outside in mid-summer.

They are vulnerable to grasshoppers and slugs. Their tender new growth would be attractive to aphids and deer.

However, of most concern is a fungal infection known as Red Blotch. The causative agent is Peyronellaea curtisii (formerly Stagonospora curtisii), whose spores are easily spread in cool, damp conditions.

Red Blotch (also called Red Fire or Red Leaf Scorch) can be seen as an irregular red area on a bulb when you buy it, although most frequently, it is seen as a red area on a leaf or bloom stalk. Since any injury to an amaryllis will produce a red pigmented area, be careful how they are handled.

The fungus infection will begin as small, reddish-brown raised or elongated spots that enlarge to cover part of the leaf or bloom stalk. The stalk or leaf usually collapses as a result of the infection. There is often a yellowed area around the spots that gives the impression of sunburn. Look for reddish-brown, pimplelike fruiting bodies that will develop in the center of the affected area.

Most growers will discard heavily infected bulbs. The fungus can be controlled, although it is best not to allow it to take hold of your plants in the first place. Fungal sprays and drenches can be used to control the disease and many fungicides are labeled for this use. Repeated sprays during the growing season of Chlorothalonil, Iprodione, or Bordeaux mix have all proven effective. Producers often use a heat treatment or a drench of 1% bleach as a preventive or to control light infestations on dormant bulbs. Read and heed label directions completely if using a fungicide.

Red Blotch is a persistent infection that affects Narcissus spp. as well, so do not store these bulbs together. Suppliers today generally do not allow infected bulbs to enter the marketplace. Be cautious about pass-along and plant exchange plants most of all.

About the author:

Carol Allen describes herself as a committable plant-a-holic. She has more than 25 years’ experience in the horticulture industry, with a special interest in plant pests and diseases; is a Licensed Pesticide Applicator in the state of Maryland; and is an ISA- Certified Arborist. She can be contacted at carolallen@erols.com.