AMES, Iowa - It might not quite feel like it yet, but spring is just around the corner in Iowa. With it comes preparation for spring planting and flowers. When is the right time to remove mulch and soil put in place to protect flowers during harsh winter conditions?
The timing can be tricky but Iowa State University Extension and Outreach horticulturists can help navigate challenges. To have additional questions answered, contact the ISU Hortline at 515-294-3108 or firstname.lastname@example.org.
To reduce the chances of crop damage from a late frost or freeze, leave the mulch on as long as possible. Removing the mulch in March may encourage the plants to bloom before the danger of frost is past. Temperatures of 32 degrees Fahrenheit or lower may severely damage or destroy open flowers. Since the first flowers produce the largest berries, a late spring frost or freeze can drastically reduce yields.
To determine when to remove the mulch, periodically examine the strawberry plants in spring. Remove the mulch from the strawberry planting when approximately 25 percent of the plants are producing new growth. New growth will be white or yellow in color. (If possible, the winter mulch on strawberries should remain until mid-April in central Iowa. The average date of the last 32 F temperature in spring normally occurs in late April in central Iowa.) When removing the mulch, rake the material to the aisles between rows. If there is a threat of a frost or freeze later in spring during bloom, lightly rake the mulch over the strawberry plants.
Remove the soil in late March or early April in southern Iowa, mid-April in northern portions of the state. A frost or freeze in early spring shouldn’t harm the roses.
After removing the soil, prune out any dead wood. Live wood is green and possesses plump, healthy buds. Dead wood is light to dark brown in color. When pruning, make the cuts about 1 inch below the dead, brown-colored sections. Remove the entire cane if there is no sign of life.
Remove the mulch in late March/early April in southern Iowa, early to mid-April in northern portions of the state. Removing the mulch earlier in the year may encourage premature growth which could be damaged or destroyed by a late hard freeze.