Gardeners should proceed with caution despite warmth

Freezing temperatures still a threat to many annuals

3/20/2012

Gardeners need to proceed with caution thanks to Mother Nature's decision to turn up the heat several months too soon.

Tuesday's the first day of spring -- also known as the spring equinox because we have equal parts of sunlight and darkness -- and we're setting high-temperature records like crazy.

According to the National Weather Service, the normal temperature at this time of the year is 50 degrees for the high with the low of 32.

Compare that to Monday, when the official high temperature hit a record of 81, which is more than 30 degrees above average for that date.

These numbers have serious consequences for your lawn and garden.

The average soil temperature most seeds need to start sprouting is 55 degrees. And that includes the weeds. If you like to apply a pre-emergent herbicide to fend off the crabgrass, now is a good time to do it. The Ohio State University shows soil temperatures in our region right at the 55-degree range, and it is usually a good rule of thumb to apply the crabgrass control when you see the bright yellow forsythia start to blossom.

If you are looking to reseed your lawn, skip the pre-emergents and toss some regular grass seed down. The warmer soil temperatures will give your grass seed a bit of a boost.

But don't forget that the freezing point is 32 degrees and that's too cold for most annuals to survive. Even though you see beautiful flats of flowers popping up in your favorite home and garden centers, it is still a little too early to put them in the ground.

Cool-season varieties such as pansies, violas, bachelor's buttons, marigolds, and nasturtium can handle some cooler weather, but unless you are planting them in a protected area, I wouldn't risk it yet. Some cool-season vegetables such as peas, spinach, and broccoli also can handle a bit of frost.

The National Oceanic and Atmospheric Administration says the first frost-free date will be May 16, a good two months away. So keep those seeds going inside until we are sure the coast is clear.

What you can do: you probably have at least 100 pages of your favorite catalogs marked with garden ideas and plants you want to grow. Get those seeds ordered if you haven't started growing them inside already and you can always take advantage of the warm weather to do yard cleanup work.

Kelly Heidbreder writes In The Garden, The Blade's weekly garden column.

Contact her at: getgrowing@gmail.com.