MAY
2005

 

 

 

By
B. Rosie Lerner
 
Extension Consumer
Horticulturist
Purdue University

 

 

 

 

 

05-05-05

Gardeners Fret Over Freeze

Much of Indiana experienced freezing temperatures this week, causing concern among backyard gardeners. Though there's not much we can do about the weather, many gardeners wonder if something can be done to help their plants recover and protect them from future frosts.

Most gardeners are concerned with newly planted flowers and vegetables. Cool-season plants, such as broccoli, cabbage, peas, potatoes and pansies, should be just fine. Frost-tender vegetables and bedding flowers, such as tomatoes, peppers, petunias and marigolds, can be covered with straw or with tents made of fabric to give a few degrees worth of protection. This is often just enough to get them through. Some support to keep the weight of the fabric up off the plants would be helpful in preventing physical breakage of the tender stems.

Tender garden plants that have already experienced damage from cold temperatures will likely outgrow it, depending on the severity. Plants that have freeze damage will initially appear water-soaked but then quickly appear more scorched, as the plant cells lose their liquid content. Often, only portions of a plant will be affected, and those stems and leaves can be snipped back and, in many cases, the growing point of the plant will survive and produce new foliage.

The biggest concern right now would be strawberry plants. Many cultivars are currently in bloom and 30 F is the critical temperature that can cause considerable damage to the flowers. For those strawberry gardeners who didn't get their plants covered, damaged foliage will be replaced, but there may not be much of a strawberry crop this year.

Trees and large shrubs are much more difficult to cover for frost protection, but, fortunately, the temperatures experienced this week were above the critical injury point for most fruit and landscape trees at this stage of their development. Most fruit trees are at or beyond petal-fall throughout much of Indiana. Temperatures would have to dip down to 28 F or lower to cause much concern after petal fall.

Freezing temperatures can damage newly expanding foliage on landscape plants, causing leaves to appear tattered later as they mature. There is a good article about freeze injury to landscape plants at the Purdue Plant and Pest Diagnostic Lab "Picture of the Week" Web site, http://www.ppdl.purdue.edu/ppdl/weeklypics/Weekly_Picture6-25-01-1.html.

 

Writer: B. Rosie Lerner
Editor: Olivia Maddox