The trick to “forcing” bulbs to flower out of season is to realize that when planted outdoors in the fall, the bulbs are not completely dormant. During late fall and early spring, when the soil is cool but not frozen, the bulb’s roots and flower buds grow. You need to replicate this in your home by planting it in a moist soil mixture and maintaining cool (but not freezing) conditions. By tricking them into thinking they’ve spent the winter outdoors, they’ll be as eager for the blooms as you are to enjoy them.
- Bulb quality is important: Purchase large, good quality bulbs as soon as they are available in stores, by mail, or online. Avoid wilted, damaged and undersized bulbs. If possible, choose shorter or miniature varieties.
- Pot size: The traditional choice of pot is a bulb pot – wide and short – typically 7.5cm (3in) high. The wide base makes tipping less likely when growing taller plants. Small bulb types (such as crocuses) are good in slightly tall pots because they do not require additional stability. But in the end, any pot will suffice as long as it provides sufficient depth and has good drainage.
- Pot Depth: The pot should be deep enough to hold at least 5cm (2in) of potting mix plus the height of the dormant bulbs. Choose a deeper pot if the bulb will stick above the edge of the pot (exception: amaryllis).
- Potting: Add at least 5cm (2in) of sterilized soilless potting mix, leaving enough room for the bulb to sit just below the edge of the pot when planted on top of this first layer. Fill the pot for an impressive display: point tip up, leaving 1-2cm (0.5-1in) between bulbs. Cover all but the tips with additional potting mix. Water well and allow them to drain completely. A label indicating the variety/variety, planting date, and end date of the cooling period. Tip 1: Plant only one variety of one type in each pot: a mixed pot is unlikely to bloom in unison. You can still get a mixed effect, using multiple bowls with separate types and varieties. Tip 2: Space out planting dates to extend the length of time you’ll have spring flowers to beautify your home.
- Temperature: Bulbs need constant cooling temperatures (2-7°C/35-45°F). Many of us don’t have a root cellar or cold room anymore, but your refrigerator provides the perfect environment (but avoid storing it with apples, avocados, bananas, berries, cantaloupe, and other ethylene-producing fruits). An attached garage may work, but the temperature may fluctuate too much (too warm to too cold) which will lead to poor results.
- Chilling Period: Chill your pots in the dark for 12-20 weeks (see below for species-specific cooling period). If you shorten the time, the plants and flowers may end up stunted and misshapen.
- Check Regularly: Water to keep the potting mix slightly damp but not wet. If it stays too damp, mold and rot may develop. Remove diseased bulbs. Bulbs may start to grow before the ‘official’ chilling period has finished – go to step 8. When the buds reach 5-8cm/2-3in in length.
- End of cooling period: Bring the pots to a cool, bright location but avoid full sun. If it has not already begun to grow, it may take 2 to 3 weeks for the bulb to send up buds and flowers. When the buds start to show a little color, move the pot to a warmer, brighter location. But keep in mind that the warmer the location, the shorter its flowering period.
Recommended chilling weeks
Amaryllis: Does not require refrigeration, but may take 6-8 weeks to flower after planting.
Saffron: 15 weeks
Daffodils: 15-17 weeks
grape hyacinth (Muscari): 14-15 weeks
Lilies: 11 to 14 weeks, with the possibility of purchasing pre-chilled bulbs. Just place these things and wait for flowering.
Paperwhites: No refrigeration required.
squill (Sila): 12-15 weeks
Tulips: 14-20 weeks
Tulip Tip 1: Point the flat side of the tulip bulb outward from the pot so that the first leaf grows outward for an attractive, tidy appearance.
Tulip Tip 2: Remove the brown paper covering (optional).
(Earl Gardens in Saskatoon).
This column is provided by the Saskatchewan Perennial Society (SPS; saskperennial@hotmail.com). Visit our website (www.saskperennial.ca) or our Facebook page (www.facebook.com/saskperennial) for a list of upcoming horticultural events
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