Soil Temperature Basics: What’s the Best for Transplanting Vegetable Starts & Seedlings?
Check the soil temperature before you transplant your vegetable seedlings and starts.
Vegetables need specific soil temperatures to grow properly, as Tricia mentions in our new video on Planting Vegetables.
HOW TO CHECK SOIL TEMPERATURES
We have two soil thermometers, one with a dial display, and the other with fluid that rises in a tube to show the temperature.
Simply push either thermometer a few inches into the soil, and wait about a minute until the reading is stable.
Keep an eye on the weather forecast too. Remember, you want the soil to be at the most conducive temperature and have a good chance of maintaining that temperature.
You can control the soil temperature to some extent—tips for that below.
DETERMINING PROPER SOIL TEMPERATURES FOR TRANSPLANTING SEEDLINGS
Vegetables can be baffling. Sometimes they need one soil temperature to germinate, and a different soil temperature to grow as plants.
The seed packet will give you the soil temperature required for germination.
When it’s time to transplant the seedlings into your garden, look up the plant-growing temperature on vegetable charts.
The biointensive classic, How to Grow More Vegetables, has charts of soil temperatures (for both germination and plant-growing). These charts originated in the leading reference for commercial vegetable farmers, Knott’s Handbook for Vegetable Growers.
Another excellent omnibus book for vegetable gardeners, The Vegetable Gardener’s Bible, gives some general rules for optimal soil temperatures for transplanting:
* 60º to 65ºF for cabbages and beans
* below 75ºF for corn
* 75ºF for peppers
HOW TO RAISE SOIL TEMPERATURES
Before you plant, you can warm up the soil temperature by spreading a layer of Thermal Green Mulching Film. Then plant through holes cut in the film, or remove it altogether at planting time.
If a drop in temperature occurs after the seedlings are planted, protect them with floating row covers that will allow rain and sunlight to get through to the transplants. Here’s the scoop on how to choose and use row covers.
Give your transplants the right soil temperatures and they’ll reward you with their best crops!
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