How to treat unplanted spring-flowering bulbs, an amaryllis when through flowering, and houseplants dropping leaves, are some of the common indoor gardening questions this time of year. Many also ask if there are food crops that you can grow indoors during winter.
If you purchased spring-flowering bulbs this fall but didn’t get them all planted, what should you do with them? Such bulbs really can’t be held over until spring, or for another year, so go on and plant them in pots. If you wait until spring to plant them outside, or in pots, they will start growing with no roots, so won’t be successful. Planting them now allows roots to form before they start growing tops.
To grow roots, and receive the cold they need to flower, place potted bulbs in a cool (40 degrees F or less) but non-freezing location, ideally for 10 to 12 weeks. This could be an unheated garage or basement. Or, you could place them outside in a protected area, covered with plenty of bark mulch, straw, or soil. Then remove when growth starts in spring.
If you got an amaryllis for the holidays, how should you treat it once it has finished blooming? Once the flower stalk is finished, leaves emerge. Keep the bulb watered and fertilized lightly through the winter. This helps it build up reserves for next year’s bloom. You can then place the potted bulb outdoors in summer, keeping it watered if needed. Then in early fall bring it indoors, and decrease watering over several weeks until stopped altogether. Remove leaves as they die back, and let the bulb “rest” for about eight weeks. Then resume watering.
If you had an amaryllis, and followed this process but got no bloom this year, it may not have built up enough food reserves during the year. If you just got leaves, keep the bulb watered and fertilized, and hopefully this coming year it will bloom once again. Sometimes after being “forced” they require a couple years before reblooming.
If you have a houseplant, such as a jade plant, and the leaves are turning yellow and dropping off, what can you do? With a jade plant, leaves dropping off is likely a sign that the soil is staying too wet. As with most houseplants, too little water is better than too much. If in doubt, don’t water, especially with “succulents” such as the jade plant. Make sure the plant is not in a pot with no drainage, nor sitting in a saucer of water. Using a clay pot, which dries out faster than plastic, also is good for plants that don’t need much water.
Make sure with houseplants that there is not a layer of gravel or pebbles in the bottom of the pot. Some recommend this for drainage, but in reality, it only creates an area where water gathers and roots rot, or decreases the amount of soil in the pot.
If you’re eager to grow some of your own food, or at least to see something green this time of year, are there any crops you can grow indoors? In addition to some herbs and sprouts, microgreens would be a good choice. These simply are the immature greens of crops such as lettuce and their relatives, leafy vegetables, and even some edible flowers and buckwheat. Some catalogs sell special microgreen mixes, often with various flavors and colors of leaves. Harvest leaves when plants are only two inches tall, only two or three weeks after they germinate. Grow in seed sowing mixes in shallow containers. They need at least 4 hours of direct sun a day, as in a south-facing windowsill, or you can grow them under plant grow light fixtures.
Dr. Leonard Perry, Horticulture Professor Emeritus
University of Vermont