Tired of cold, gray days outside the window? Catch a little springtime and bring it indoors by forcing branches from spring-flowering shrubs into bloom.

If you’re pruning shrubs for shape or size at this time of year, branches for forcing can be a bonus, said Doris Taylor, manager of the Plant Clinic at The Morton Arboretum in Lisle. You can enjoy fuzzy pussy willows or big pink magnolia blooms on stems you otherwise would discard.

Why would a bush bloom indoors? Shrubs that bloom in early spring already have their flower buds. Toward the end of winter, those buds begin to swell and get ready to open, waiting for the signals of longer, warmer days and spring rains. When you bring a branch with buds into a heated room and place it in water, you trick the buds into reacting as though spring were further along than it really is.

“Don’t try it too early,” Taylor said. The shrubs need to spend at least six weeks outdoors in cold winter weather before they will undergo the chemical processes that lead to blooming. By early February, most have met that requirement.

The best plants for forcing include forsythia, flowering quince, cherry, plum, magnolia, pussy willow, crab apple, Cornelian-cherry dogwood, redbud, serviceberry and witch hazel, Taylor said. Shrubs that flower later in the year, such as butterfly bush, won’t have any flower buds yet, so forcing them won’t work.

If you are planning to force branches, don’t get carried away with your pruning and remove too many. “You still want flowers in your garden in March and April,” she said. Leave the shrub looking balanced and shapely, with plenty of flower buds.

Indoors, make a fresh cut at an angle at the bottom of each branch, and place it in water immediately. That will prevent sap from sealing over the cut end, which would keep the branch from absorbing water. The angled cut will create greater surface area to absorb more water.

Place the vase in indirect light. Change the water every couple of days, as you would for cut flowers.

“It may take seven to 10 days for the buds to open,” depending on the plant, Taylor said. If a few buds fail to bloom, they may have been damaged by a harsh freeze or dried out from cold winds. The flowers will last longer if the branches are kept in a cool room, rather than a warm one.

Gray winter isn’t over, but a vase full of blooms can make it brighter.