Planting a home garden at the first sign of spring weather might cause big problems later, especially when more freeze days are likely ahead, a Purdue Extension horticulture specialist says.
"Don't be fooled by the odd warm day we will be experiencing here and there over the next few weeks," warned Larry Caplan, Extension horticulture educator in Vanderburgh County in southwest Indiana. "The soil is still quite cold, so anything you plant is just going to sit there."
Caplan said that since the soil is wet, digging and tilling now ultimately will cause more compaction problems than gardeners otherwise might have.
He also noted that there is still plenty of opportunity for a freeze, where the temperature drops below 32 degrees Fahrenheit. Generally, the average period of the last freeze date is April 11-20 for the southern portion of Indiana and April 21-30 for the northern.
Caplan cautioned that those dates are only averages, meaning that there is a 50 percent chance another freeze will occur after these dates. "We still have a 10 percent chance of a freeze up to two weeks after these dates," he said.
A graphical map showing the average freeze dates in Indiana and other Midwest states is available on the National Oceanic and Atmospheric Administration's website at http://www.crh.noaa.gov/images/ind/freezedates_32_spring.png.
Caplan said "warmth-loving plants" such as tomatoes and peppers are most susceptible to early-spring cold snaps. Even a brief exposure to 32 degrees will cause damage to the foliage and plant. And if the soil hasn't warmed "the plant will just sit there and refuse to grow, even if there isn't a frost."
Caplan said cold-tolerant plants, such as broccoli and cabbage, are not hurt by a light freeze of 28-32 degrees. "But if the temperature falls not much lower than that you'll see damage," he said.
Gardeners can find out when it is safe to plant their vegetables by referring to the Purdue Extension publication, Indiana Vegetable Planting Calendar, available at http://www.hort.purdue.edu/ext/ho-186.pdf.
The publication lists more than 55 of the most common vegetables planted in Midwest gardens. It divides Indiana into four districts, enabling gardeners to choose the best dates to plant individual crops based on geographic location.