The coldest part of the year in the South Carolina is a couple of cool nights that might dip down into the mid 20s—not terribly cold compared to many regions of the country but frigid enough for a warm winter coat. Depending on if you live in semi-tropical South Carolina or the frozen Rocky Mountains, your early spring plantings may be only few weeks or as much as a few months away. So how do you know the right time to put out your spring seeds?
Take Your Soil’s Temperature
One very helpful tool for small gardeners is a simple soil thermometer that can determine if your garden soil is warm enough for seed germination. There are several types of soil thermometers available, including traditional glass models and newer digital models that can either be purchased at your local nursery or through an online garden supplier.
To take a correct temperature, place the soil thermometer at the specific planting depth of your crop. To avoid breaking a glass thermometer, use an ice pick or screw driver to dig a pilot hole. Pilots holes should not be too large, as incorrect readings are common when the glass bulb or digital sensor is not in direct contact with the soil. Take several temperatures in different spots, at different times of the day and for several consecutive days to ensure accuracy. Try to avoid taking readings at non-representative sites, such as permanently shady spots.
Once you soil temperature reaches 40 degrees F, you are ready to plant your first spring crops from seed.
Your First Crops
Lettuce, arugula, kale, parsnips, peas, spinach and radishes are all ready to be planted once the soil has achieved the critical 40-degree mark. A few weeks later when the soil has warmed to 50 degrees F, your garden is ready for the next wave of spring plantings which include favorites like onions, leeks, Swiss chard and turnips. Broccoli, cabbage, beans, beets, cauliflower and carrots all should wait until soil temperatures reach at least 60 degrees F for optimal germination rates.
Even if your soil is ready for planting, be sure to regularly monitor air temperatures in your local area and be ready cover sensitive crops if heavy frosts or late freezes are forecast.