Extension News

Ask the ISU Extension Garden Experts About: Spring Blossoms, Flowering Dogwoods and Black Hills Spruce

flowering redbud blooms

1/20/2011

How to force spring blossoms indoors

How do you force branches of spring-flowering trees and shrubs indoors?

Forcing can be done as soon as the buds start to swell. Forsythia and pussywillow can be forced as early as February. It's best to wait until March for more difficult-to-force ornamentals, such as crabapples, magnolias and redbuds.

Select branches containing round, plump buds (narrow, pointed buds are usually leaf buds; flower buds are generally larger and have a more rounded shape). Make clean, slanting cuts 1 to 2 feet from the tips of branches with a sharp hand shears. Selectively remove branches that won't destroy the natural shape of the plant. If pruning fruit trees in late winter, gather some of the pruned material for forcing indoors. If possible, collect the branches when temperatures are above 32 degrees Fahrenheit. If the plant material is frozen when collected, submerge the branches in a tub or pail of water for a few hours.

Later, set the branches in a tall container of water and place in a dimly lighted, cool (60 to 65 F) location. Spray or mist the branches two or three times a day to prevent the buds from drying out. Also change the water in the container daily during the forcing period. Daily changes of water should inhibit the growth of bacteria and fungi which could interfere with the absorption of water by the branches. When the flower buds begin to open, move the branches into a bright room. Keep the flowering branches out of direct sunlight and in a cool location to prolong the bloom period. 

The time period required to force branches into bloom depends upon the plant species and collection date. Forsythia and pussywillow generally take only one to three weeks to force. Magnolia branches may take three to five weeks. The closer it is to the plant’s normal outdoor flowering period, the less time it will take to force the cut branches indoors.

Flowering dogwood not a fan of Iowa winters

Can the flowering dogwood be grown in Iowa?

The flowering dogwood (Cornus florida) is a beautiful tree that is widely planted in the southern United States. Unfortunately, the flowering dogwood is not reliably winter hardy in most parts of Iowa.

Cows munched on Black Hills spruce trees

Cows have defoliated the lower branches on several Black Hills spruce trees. Will the trees  recover?

The presence or absence of vegetative buds on the defoliated branches will determine the extent of damage to the Black Hills spruce trees. If vegetative buds are still present on the branches, the buds will break in spring and produce new green growth. The trees could recover fully in two or three years. 

If the buds have been destroyed (eaten by the cows), the affected branches will not be able to produce new growth. The branches above the damage will continue to grow. The destruction of the tree’s lower branches will not kill the trees, but will negatively impact their appearance and function.

To learn more about caring for Iowa trees, visit the ISU Extension Online Store at www.extension.iastate.edu/store/ and search for trees. Publications that are available for purchase or downloading include Selecting an Arborist - Reiman Gardens, RG 0214; Pruning Ornamental Shrubs, PM 1958; Pruning Trees: Shade, Flowering, and Conifer - Sustainable Urban Landscapes, SUL 0005; and Landscape Plants for the Midwest, PM 0212.

Contacts :

Richard Jauron, Horticulture, 515-294-1871, rjauron@iastate.edu

Willy Klein, Extension Communications and External Relations, 515-294-0662, wklein@iastate.edu