by Andrea Laine, EMGV
Spring is in the air. You can feel it in air temperatures in the 60s and 70s. You can see it as tree buds swell and leaves on flowering shrubs like hydrangea begin to unfurl. And you can hear it in the voices of people all around town – Durham dwellers seem downright giddy about an early arrival for springtime. That is, unless they are gardeners. Gardeners understand that despite a 10-day forecast of spring-like temperatures (as of this writing), our area is still several weeks away from the average last freeze date which is April 28.
Prepare now so you are not caught off-guard later. If temperatures dip below 32-degrees Fahrenheit some plants will need protection in order to have the best shot at flowering in late spring and summer. In my landscape this includes the gardenias and non-native varieties of hydrangeas. The plants themselves will generally be okay, but flower buds and new growth may die in a freeze. Blossoms on fruit trees are also vulnerable to late frosts.
You can protect your plant, shrubs and small trees by giving them a protective cover when a frosty night is predicted. Burlap, bed sheets, blankets and agri-fabric are the best materials to use. Do not use plastic sheets or metal buckets. The purpose of covering a plant is to trap the radiant heat that is in the soil. Therefore, covers will be more effective if they go all the way to the ground. Covers should not touch plants; use stakes to hold covers off plants as much as possible. Remove the cover the following morning when temperatures rise.
Locate protective materials now so that you and your plants are ready to guard against potential frost damage. Cut the stems of flowering bulbs to enjoy indoors prior to a late freeze. The actual bulbs will endure the cold; the flowers likely will not.
Urban Horticulture Note No. 1: Durham’s Weather, NC Cooperative Extension Service
Leaflet No. 604: Protecting Plants from Cold Damage