Lucky you if you got a giant amaryllis (Hippeastrum) this year! They’re popular holiday plants because of their large beautiful trumpet-like flowers. The trouble is, like poinsettias, most people just don’t know what to do with them after the holidays.
Once the flowers fade cut the stem off leaving about 2 to 3 inches but don’t cut off the leaves! The leaves need to replenish the bulb so that it can bloom again. If the long strap-life leaves are really floppy and drive you crazy or have become a cat toy, you can tie them loosely to a bamboo stake. Put the plant in a sunny window, water when the top of the soil feels dry and fertilize every three to four weeks with a diluted organic fertilizer for flowering houseplants and let it recover from it’s ordeal.
As a rule, I don’t fertilize newly potted plants for at least six months, but amaryllis bulbs are an exception, they expend almost all of their energy to produce multiple large flowers, followed by leaves. If you took the bulb out of the pot at this point you would see that it actually looks slightly smaller than when it was potted! In human speak, this plant has just run multiple marathons.
As soon as temperatures stay around 60 degrees or above, my amaryllis go on summer vacation—to my deck stairs where they get morning sun and a bit of dappled shade later in the day. This is pretty similar to what they would have in their native habitat where they grow between the large roots of trees.
In August, I remove the bulb from the pot, gently brush some of the soil from the roots and replace it with new sterile potting mix. If you don’t want to do that, try removing only an inch or two of the soil around the bulb ( you can scrape it out with a plastic spoon) and replacing that with some fresh planting mix.
Amaryllis should be repotted every couple of years. You can find specialty clay pots for amaryllis bulbs that are tall and heavy so that the weight of the flowers doesn’t cause them to topple over. Just remember that they like to wear their shoes a little snug and should never be planted in a pot that’s more than 2 inches larger in diameter than the bulb. Planting an amaryllis bulb in an oversize pot is asking for trouble and will lead to soggy soil and a rotten bulb. Likewise always use a well-draining potting mix that contains organic matter.
If and when you notice the leaves turning yellow, cut back on watering and stop fertilizing. Move the plant to a location (if it’s outdoors) where it will stay dry and cool (out of the rain and sun). This is a signal that the bulb is going dormant
Some horticulturalists say that amaryllis do not go dormant and others say they need to have a forced dormant period in order to re-bloom. How do you force a plant to go dormant?”
About fourteen weeks before you want blooms, cut back on watering and discontinue fertilizing the plant. The leaves will gradually yellow and wither. When this happens you can cut them off and move the plant to a cool area out of direct sunlight. Again you stop watering or water only enough to keep the bulb from shriveling and wait for new growth to show at the tip of the bulb. Once new growth starts you can water as needed and move the plant back into a window.. In approximately fourteen weeks, you’ll have beautiful blooms again.