Other Uses (Forcing Bulbs, etc.)
Bulbs for Outdoor Containers
Many summer-blooming bulbs take beautifully to container-growing. To get a longer growing season, you can start many of them indoors early in spring and move them outdoors, pot and all, when temperatures are warm enough. Tuberous begonias, caladiums, calla lilies, dwarf cannas, dwarf dahlias and zephyranthes are some of the best to try.
Whether potting bulbs for indoors or outdoors, make sure the pot has good drainage by placing gravel or broken pottery in the bottom of the pot. Position the bulbs at the recommended depth and water well once and then, water sparingly until top growth appears. After that, keep the soil moist and remember that clay pots dry out very quickly. In hot weather, water daily. Turn the pots a bit each day to keep stems straight.
Bulbs for Cutflowers
You may want to grow some summer bulbs -particularly dahlias, callas, lilies, gladioli, and anemone coronaria - primarily for cutting. A separate bed, or a section of your vegetable garden, is often the best solution for growing large quantities of these bulbs. If good drainage is a problem, make a raised bed. Follow the same recommendations for spacing and depth (given in the following pages) as you would for using them in the border.
Bulbs as Houseplants
Several of the summer bulbs do well as houseplants. Be sure to provide at least 4 to 6 hours of sun each day, adequate humidity, and, for some bulbs, cool enough temperatures. Over-watering of summer bulbs indoors is as bad as poor drainage outdoors. Let the surface become almost dry to the touch before rewatering. Caladium and cyclamen are the exceptions; they need constant moisture. Use a porous soil mixture, not garden soil and coarse drainage material in the bottom of the pot. Set the pots on trays of pebbles with water added to increase humidity or group plants together.
Most summer bulbs grown indoors require temperatures ranging from 4°C to 15°C. Even if you can only offer temperatures from 15°C to 21°C, you can still grow a wide selection of bulbs including gloriosa lily, vallota, eucomis and the amaryllis relatives. Most bulbs grown as houseplants need a rest period of at least a few weeks in winter. Water minimally, if at all, during this period.
Forcing Bulbs Indoors
A container of sunny daffodils, or cheery crocus, blooming on your windowsill in February, can be a treat. In order to enjoy these beautiful blooms in winter you must make plans in late fall. Depending on the type of bulb, it may take anywhere from 1 to 4 months from the time they are potted up until they bloom.
Potting up: Select a container that is twice as deep as the height of the bulbs. Shallow, heavy containers will not topple as readily as high containers. If you are planting your bulbs in potting mix, your pot must have drainage holes. Fill pot with mix (at least 2" for root growth). When bulbs are placed on this layer, their tops should be even with the rim of the pot. Use several bulbs for an attractive display. Cover with potting mix and water in to settle.
Cooling/Rooting Period: Place pots in a cool (45°F, 7°C), dark place for 6 to 15 weeks, depending on the variety. Soil must be kept moist and should not be allowed to freeze during this time. A refrigerator, root cellar, or cool basement is fine. Remove pots from cold storage when the appropriate time has passed or when white roots are showing through drainage holes or stems are 2" high. Be careful if using a residential refrigerator. Ethylene, which is a gas produced by certain fruits and vegetables, can retard flower development in the bulb. Avoid storing the following fruits and vegetables anywhere near your bulbs. Passion fruit, apple, avocado, apricot, cantaloupe, kiwi, peach, banana, tomato, honeydew, cucumber, pepper, pineapple.
Forcing Blooms: Most types of bulbs will bloom 3 to 4 weeks after you bring your bulbs into a warm, bright room. Pots should be kept at 60°F/15°C with indirect sunlight for one week. Move pots to a warmer room (68°F/20°C), with direct sunlight until buds take on color. Return plants to indirect light and cooler temperatures to help blooms last longer. After blooming, hardy bulbs can be planted into your garden where they will bloom again in a year or two.
Easiest Bulbs for Forcing
Large Flowered Crocus: Use at least 15 bulbs per container. They require a 12-15 week cold rooting period and can be forced in water.
Hyacinths: Hyacinths are often forced singly in glass forcing vases using only water. They can also be potted up in groups. Either way give them 4 to 8 weeks in a cool, dark place before forcing.
Iris: Dwarf Iris are suitable for forcing, especially Iris reticulata and Iris danfordiae. Place in cold treatment for 8-12 weeks. These species can handle very cold temperatures. When you take these out of cold treatment be sure to keep temperatures below 65°F or they may not bloom.
Tulips: Tulips require a long (12-15 weeks), even cold treatment. Plant with flat side of bulb facing rim of pot for a more attractive display. Early, shorter varieties are the easiest to force.
Daffodils: Plant in larger, deeper pots to accommodate long, heavy roots. Place in cold treatment for 12 to 16 weeks. Daffodils need very bright, direct sunlight to bloom properly.
Scilla and Grape Hyacinths: Cool for 10-16 weeks. Use lots per pot.