If you have a heated greenhouse, you have a big advantage in growing amaryllis, those bulbs with huge, dramatic flowers that are such popular holiday gifts. Pretty much anybody with a bright window can get an amaryllis bulb to bloom, but to keep the plant alive and get it to flower again next year requires more sunlight and warm temperatures.
These are tropical and subtropical plants, native to the Americas, including Mexico and the Caribbean. They’ve now been selected and hybridized for ever larger and more spectacular flowers, often with double petals or multiple stems per bulb, in splashy patterns and shades of red, pink and white.
Like all bulbs, an amaryllis bulb contains a complete plant and flower that is ready to sprout, given moist soil and sunlight. In a window, you’ll have to keep rotating the pot so the sprout doesn’t lean; in a greenhouse, it’s easier to keep the stem straight.
Many people simply discard an amaryllis after it blooms, since the bulbs have become relatively cheap. But with a light-filled heated greenhouse (or a very sunny warm porch), you can more easily get an amaryllis to re bloom next year. (You can provide the light with a fluorescent light setup, too, if you’re not using it to start seeds.)
It’s actually the period after blooming when an amaryllis is most actively growing and needs the most sunlight. That’s when the leaves are collecting light to power the production of a new bulb-encased flower for next year. During the winter in Chicago or anywhere in the northern latitudes, it’s hard for a window to provide enough juice.
I snip the flower stalk off when the bloom fades and concentrate on nurturing the leaves. I keep the soil moist and fertilize once a month with a solution of fish emulsion. Once the weather is safely frost-free—in May around here—I move my amaryllis plants outside into the garden in filtered shade. The bold, shiny, strappy leaves are a nice contrast when I set the pot among finer-textured garden plants such as ferns.
I keep watering and fertilizing the amaryllis until late summer. Then I knock off watering and let the leaves die back as the plant goes dormant. I cut the dead foliage off and move the pot to a cool, dark place (the basement is good).
After it’s had a rest for a few weeks, I move it back into a warm, sunny indoor spot and start watering to encourage it to bloom. A greenhouse is perfect for this; you can let the autumn sunshine do its magic and move the flowers into the house temporarily as décor for holiday parties.
It takes 8 to 10 weeks for the new stalk to sprout and flower, so to have blooms for Christmas display I’d have to start forcing the bulb by late October. When I miss that window—which is usually—or if I get an amaryllis bulb as a holiday gift, I just plan on having it bloom for midwinter cheer.