If you've ever seen the massive size of a six-pointed amaryllis bloom, you won't soon forget it. These eight-to-ten-inch blooms come in a variety of colors including red, pink, orange, salmon, white and bicolors. Doubles and miniatures are also available.
There couldn't be a more foolproof indoor plant to grow than amaryllis, and they're all the more welcome, because they generally bloom in mid to late winter. The flower is started from bulbs that are nearly the size of grapefruit. The larger the bulbs, the larger and more numerous the flowers. Bulbs are commonly sold in pre-planted starter kits.
To start a bulb, plant it in a loose planting mix. Use a pot that's only slightly larger than the bulb, and position the bulb half way out of the soil. Water thoroughly and allow to drain. When soil is two-thirds dry, put plants on a watering routine. Expose plants to at least a half-day of bright light, and fertilize once a month.
On standard-sized amaryllis, the flower stem emerges before the leaves, grows rapidly to a height of 12 to 24 inches, and begins a sequence of blooms that last about a month. After bloom, cut the flower stem off just above the top of the bulb, but don't cut the leaves.
If you're growing amaryllis plants to produce blooms for years to come, water them as you would any houseplant for the remainder of the winter. During the summer, you can keep plants indoors in bright light, or set them outside. Be sure to continue fertilizing. Put plants out after all danger of frost is past, and bury pots in a partially shaded location. In early September, bring plants indoors, and stop watering.
Cut old, yellowed or dried foliage from the bulbs and allow them to rest in darkness for a month before you repot them in fresh soil and resume watering to initiate blooms.
For more information, see the following Colorado State University Extension fact sheet(s).
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Updated Friday, June 19, 2015