Forcing bulbs for indoor bloom

I don't mind Minnesota winters, but I always feel a little let down after the holidays, when the days are short and even daylight can be muted. That's when a pot of spring bulbs, radiating color and heavenly scent, like a little garden miracle, can brighten a winter day.

For many years, I've given pots of forced bulbs as Christmas gifts. Some people say it's the best gift they receive.

I keep several pots for myself, too, enough to have flowers in the house right into March.

Forcing bulbs is easy, but to have winter bloom, you need to begin now. You'll need clean pots, commercial potting soil (no garden dirt for this) and an appropriately cold place to mimic winter conditions that bring the bulbs into bloom.

If you have room in your refrigerator, that works. A heated garage where the temperature never gets below freezing is also good. According to the University of Minnesota Extension Service, most bulbs need temperatures between 35 and 48 degrees for about three months to pop their blooms.

In my old house, the unfinished basement includes a chilly corner room that was once a coal bin. A previous owner thoughtfully lined the little room with shelving, and that's where I put my pots of bulbs to grow.

While the experts at commercial greenhouses have the know-how to get pots of mixed bulbs to bloom at nearly the same time, my home experiments have not been successful at that. While hyacinths will bloom after just 11 or 12 weeks of chilling, some tulips need up to 20 weeks before they are ready to flower. My pots of mixed bulbs turned out to be messy and unappealing, with hyacinths dying back before crocuses and daffodils were even showing buds. So if you want to force different kinds of bulbs, give daffodils their own pots, put hyacinths in another, and so on.

But my favorite forced bulb is the hyacinth. They're sturdy plants and reliable, spectacular bloomers. I love their sweet smell (people who dislike the scent of Stargazer lilies might find hyacinths too much to bear in a closed winter home).

Because your goal is to have a packed display of flowers in each pot, normal gardening rules about spacing don't apply. Plant bulbs an inch apart, with the pointy end sticking out of the soil. You don't want to bury the bulbs. Water them enough so that the soil is nicely damp, but don't soak it, or you run the risk of rotting the bulbs. If you're a chronic over-waterer like me, choose a pot with drainage holes, and put a saucer beneath it.

If you have a dark room where temperatures will drop at least into the 40s, you can stick the pots in there and close the door. If you're using a fridge or garage (remember the pots can never freeze), you need to find a way to keep bulbs in the dark. An overturned box works in a garage. In the fridge, a paper bag or a plastic bag with holes poked in it, to allow the pots to "breathe," is good.

Pots shouldn't be allowed to dry out; especially in a fridge, you'll want to monitor the bulbs to make sure they haven't gone dry. I check my pots once a week, and water as needed.

Then you wait.

Blooms will last longer in a cool location where the plants are out of direct sunlight.

More detailed information about forcing bulbs is available in this U of M Extension fact sheet: extension.umn.edu/garden/yard-garden/houseplants/forcing-bulbs-for-indoor-beauty-in-winter/

For those who don't have a good cold spot to force bulbs, amaryllis and paperwhite narcissus don't need a dormant cool period. Both will soon be available in area garden centers.

While amaryllis are planted like other bulbs in soil, with the top third exposed, paperwhites are usually nestled in a bed of gravel or pebbles where there is just enough water to cover the lower quarter of the bulb. The paperwhites will send roots down into the rock, and voilà! You have sweet-smelling flowers within two to three weeks.

The biggest issue with paperwhites is that they get leggy and tip over, but there's a way to solve that problem. In what must be one of the most entertaining horticultural projects ever, researchers at Cornell University have found that once the bulbs have rooted, and paperwhite leaves are about an inch tall, adding a bit of hard liquor to water — vodka, gin, whiskey and the like — will cut the height of the plants by half to one-third and not affect flowering.

Here's the Cornell paper that explains it all:

www.hort.cornell.edu/department/faculty/wmiller/bulb/Pickling_your_Paperwhites.pdf