Garden Dilemmas, Delights & Discoveries, Ask Mary Stone, New Jersey Garden blog

Soil Temperature

an analog thermpmeter stuck in soil

Hello fellow readers, I am learning so much from all of you! On Mother’s Day, Pastor Marcia shared that soil temperatures were still too chilly for farmers to plant their crops which related to her sermon on honoring all who nurture. While shopping for plants, I met Phil from Morristown, who advised that it is too soon to plant tomatoes as our nights need to be above 40 degrees.

Planting at the right time is essential. 

No doubt, planting at the right time is as essential as water and nutrients. Following a calendar to determine the right time to plant isn’t always accurate because temperatures vary, as we experienced this year. The more precise determination of when to plant is the soil temperature. By the time this column gets to you, we are likely good-to-go on transplanting starter plants and sowing some seeds directly in the ground, but always best to be sure.

While soil temperature maps are available online, taking your soil’s temperature is the most accurate way. Many seed packets and plant labels provide the optimum temperature for planting. High-tech thermometers provide digital readings that beep when ready, but an analog soil thermometer for less than ten bucks is just as effective. They work much like the human kind, which would be the in-the-bottom variety that Mom always touted to be most accurate. Simply stick the soil thermometer probe into your soil about 6 inches for a minute or until Mr. High-tech beeps. You can even use an instant-read thermometer made for cooking.

Ideal soil temperature varies by crop. 

Check the temperatures where you intend to plant each crop. Seed germination temps range from 40 degrees or warmer for lettuce, kale, peas, and spinach, 50 for onions, turnips, Swiss chard, 60 for broccoli, cabbage, cauliflower, carrots, beans, and beets, and 70 for tomatoes, squash, corn, cucumbers, melons, and peppers. Once established, many veggies can handle cooler air temperatures as long as the soil is warm enough, which is why starter plants can give us a jump start.

Be sure to check your soil temperature midday for at least three days. Average the readings by dividing the total by the number of days taken. And no faking a fever to avoid going to school.

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Column Updated 3/14/2021

Link to an associated column Planting Following Nature 

Mary Stone, owner of Stone Associates Landscape Design & Consulting. As a Landscape Designer, I am grateful for the joy of helping others beautify their surroundings which often leads to sharing encouragement and life experiences. These relationships inspired my weekly column published in THE PRESS, 'Garden Dilemmas? Ask Mary', began in 2012. I dream of growing the evolving community of readers into an interactive forum to share encouragement and support in Garden and Personal Recoveries - seeking nature’s inspirations, stimulating growth, weeding undesirables, embracing the unexpected. Thank you for visiting! Mary

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