Forcing Bulbs Indoors

Put A Little Spring In Your Winter!

From Your Friends At Schriemer's

You can add colour to your indoor garden during the drab days of winter by forcing bulbs into bloom. Forcing causes bulbs to flower before they normally would outdoors.

Most hardy fall bulbs are candidates for forcing. However, some bulbs are easier to force than others; lilies, squills and alliums are notoriously difficult to force indoors, but can be a fun challenge for the avid gardener. Naturally smaller plants and earlier varieties are usually better candidates for forcing.

Instructions

Start the process in fall; potting in September through December will result in a sequence of bloom from mid winter through early spring. Buy the best-quality bulbs you can find. When you pick out bulbs, examine them thoroughly. You want bulbs that are firm and solid, with no mold, soft spots, or physical damage. Store tender bulbs in a cool location (8-12ºC) with good air circulation. Store hardy bulbs in the refrigerator (4ºC). Even hardy bulbs will not survive in the freezer; lacking the insulating protection of soil or snow that they receive when planted outside, the bulbs will succumb to frostbite.

It usually takes 3-5 months to force bulbs into bloom, so plan ahead. Plant your bulbs in 5- to 6-inch-diameter pots. Use pots with drainage holes, and place loose gravel at the bottom to facilitate drainage while keeping the soil from flowing out. A conventional 6-inch pot will accommodate three daffodils or hyacinths or five to six tulips. Smaller bulbs, such as crocuses or netted iris, can be forced in a 5-inch bulb pan (a pot that is wider than high). The actual type of pot doesn't matter, but if you're reusing pots, wash them first with a 1:10 bleach-to-water mixture.

Fill the pots half full with a well-drained, porous medium such as a mix of equal parts potting soil, peat moss, sand and either vermiculite or perlite. Most bulbs can be planted with the tips exposed. Don’t bury them completely unless noted in the table below. Set them so that the soil level will be about 1/2 inch below the rim of the pot. Plant as many bulbs as will fit in the pot, leaving about 1-1/2 inches of space between them. When planting tulip bulbs, face the flat part of the bulb towards the pot so that the first and largest leaf grows outward.

Water to thoroughly moisten the soil mix, and then cover the pots to keep out light. Most bulbs will need a period of cold storage in a cool, dark place like a fridge or basement to stimulate root growth. However, don't store them in a fridge in which you regularly keep vegetables and fruits, especially apples, tomatoes and bananas, as the ethylene gas they give off can adversely affect the bulbs. Check the pots weekly to be sure the soil remains moist but not wet, and do not fertilize. Note that paperwhites usually don't require this period of chilling.

When the chilling period is over, usually around the time when you can see tip growth an inch or two above the soil, it's time to bring the pots out of cold storage. Break them in gently, first in a cooler spot with indirect lighting, finally moving them to a warm, sunny spot when the shoots turn green. Rotate the pots regularly to provide even sunlight. Most bulbs will do best in a bright but rather cool location indoors. Water to keep the soil evenly moist. When they start to bloom, moving them to lower lighting will prolong the period of bloom.

After flowering, the bulbs are best discarded, as they have used up most of their energy. Adventurous gardeners can return them to cold storage and plant them out into the garden in spring, or allow them to mature and go dormant to be planted out in fall as regular bulbs, although they may not bloom the first year.

Specific Bulbs