Frost/Freeze Information and Plant Protection
Much of this information has been provided by Rosie Lerner, Extension Consumer Horticulture Specialist and Master Gardener State Coordinator from Purdue University. Additional information on horticulture can be found at http://www.hort.purdue.edu/ext/conhort.html . This information is also relevant to areas of Northwest Ohio and Southern Lower Michigan where temperatures have been very similar to Northern Indiana.
Following a particularly mild winter but cold enough to easily satisfy the chilling requirements for flowering, our spring blooming plants have had a tremendously early and spectacular display this year. Blooms are about 4 -6 weeks ahead of “normal” this year and bud counts are high. Due to the recent stretch of record warmth, it’s a bit like the grand finale of a fireworks display. While the sequence of bloom appears to be staying in order, it’s as if the season is on fast forward bringing nearly everything into bloom all together.
The likelihood of hard frost and freeze is still high in the coming weeks. According to the Indiana state Climate office <http://iclimate.org/narrative.asp >, the average date of the last freezing temperature in spring ranges from the second week of April in extreme southwest Indiana to the second week of May in the extreme northeast. Two-thirds of the time they occur within a 20- to 24-day period centered at the mean date. The trend of a later date toward the north is reversed in extreme northwestern Indiana, where the average date is about May 1 near Lake Michigan.
With regard to fruit crops, fruit set and development is susceptible to injury when temperatures drop to near or below freezing. The degree of susceptibility depends on several factors, most notably species, stage of development, and temperature (specific temp as well as duration of exposure.)
What can home growers do if frost is predicted? Small fruit plants can be covered to provide a few degrees of protection temporarily. Blankets, throws, and tarps can be used but provide stakes, wires, or other supports to keep the weight of the cover off of the plants. Straw would be useful for covering low growing plants such as strawberries and herbaceous perennials. Covers need to be removed as soon as possible after the threat is past to avoid over-heating and over-shading. It is impractical to do much for trees, large shrubs, and large garden areas.
It is important to monitor weather forecasts daily as conditions can change quickly. A temperature change of just a few degrees can have a large impact on whether we see a light frost or a hard freeze. Follow http://www.weather.gov/iwx for all your local weather information, forecasts, advisories and warnings.
Last Updated March 23rd 9:10 am