© Janet Davis
Years ago, I grew a big forsythia under my
front window, but it tended to burst into garish golden bloom just as the
delicate pink blossoms of the magnolia were opening nearby. The contrast was too much, even for me, so the
forsythia went. But every year, in
February or March, I miss that old yellow thing. 
Even though I knew it was
sure to be in bloom by the last week in April, I always liked cutting a big
armful of branches to bring indoors.
Within a week or so, they’d unfurl their gold petals, and the sight of
them in a vase on the kitchen counter while snow was blowing outside made me
feel I’d advanced the calendar six weeks.
Cutting branches from spring-flowering shrubs or trees and treating them indoors so they flower or leaf out long before they would do so in the garden is called “forcing”. Many plants will respond to this treatment. Forsythia and pussy willow are foolproof; cornelian cherry, quince and witch hazel are easy too. A little trickier but worthy a try are lilac, flowering currant, magnolia, deutzia, serviceberry, mock orange, hawthorn, redbud, bridalwreath spiraea, weigela and flowering fruit trees like apple, cherry, plum, pear and peach.
Branches can also be forced for foliage, rather than blossom. Particularly nice are the contorted branches of corkscrew willow or hazel, but you can try staghorn sumac and birch, too.
Several years ago, I chatted with Barbara Hill, an avid gardener and accredited horticultural judge, about forcing flowers and foliage.
“The best time to cut branches for forcing,” she said, “is on a sunny day, preferably above-freezing, at noontime when the sap is plentiful. Rather than smashing the bottom of the stem, make small slits and peel the bark back to expose the stalk. Immerse the branches in warm water – I use a bathtub – for 12 to 20 hours, turning the hot water tap on every once in a while to keep the water warm. Then stand them in a jar or bottle away from direct sunlight for the first while. As the buds start to open, bring them closer to the light.”
“Some of the blossoms that are normally
dark pink, like flowering quince and crabapples,
will force a peach color
because they’re not getting outside sunlight.
But they’re delicate and lovely.”
“Forsythia will come on without spraying,” said Hill, “but some things, especially when forced for leaf growth, need to be sprayed once or twice a day with tepid water. Another trick is to take your pail or jar with the branches and put the whole thing inside a clear plastic bag. If you cut your branches in January, it might take four weeks for them to open. cut them in March and it could take two weeks, so the closer the time to their natural bloom, the faster they’ll come one.”
Years ago, I read an article in the New York Times that mentioned a forcing trick originally given in an old book of household hints. It recommended putting a pail inside a plastic laundry bag, filling it three-quarters full with warm water, putting the branches in the warm water and adding a cotton ball soaked in sudsy ammonia, then tying the bag closed. The pail was to be kept in a warm place out of direct sunlight, and flowers were promised “astonishingly quickly”. Presumably, the ammonia acted as a ripening agent (in the same way that ethylene in plants promotes ripening and leaf fall). I haven’t tried this method, nor had Hill, but it’s certainly worth an experiment if you have lots of forcing material in your garden.
Anything to hurry spring a little.
Adapted from a column that was published originally in the
Toronto Sun