It’s the beginning of May, so it’s time for my annual appeal to hold off on planting out your tomatoes and other cold-sensitive crops. I think the plea may fall on deaf ears this year, because looking ahead at the 10-day forecast here in upper Montgomery County, I see only one night that might fall below 50 degrees F., and only barely below. Days are nice and warm. It feels like tomato-planting time.
Let’s just state a few caveats, though, and then I’ll let you go about your business.
- In many recent years, we’ve had a substantial drop in temperature in mid-May, even after summerlike conditions had already taken hold. That may not happen this year, but it still could.
- It looks like we are finally going to get some rain coming up—hurray!! We really need it. But a rainy period isn’t the best time to put tomatoes in the ground, not because you get wet, but because the plants do. Wet leaves and splashing mud will make them more susceptible to fungal diseases that could be lurking in the soil. If you do plant during or before a lot of rain, make sure the soil is covered by mulch.
- Most importantly, the air temperature at planting time matters less than the soil temperature, and at least where I’m measuring, the soil temperature is far below the ideal 60 degrees F. that tomatoes prefer. Get yourself a soil/compost thermometer and stick it in the ground where you intend to plant; see for yourself. Cold soil temperatures hold back the growth of plants that like it warm, and fruit may be poorly formed.
My tomato and pepper plants are still inside under lights. They’ll venture outside to start hardening off this weekend, so that in another week or so, if the forecast looks good, I’ll be able to consider putting them in the ground. But I’m definitely going to check that forecast and stick that thermometer in the soil.
If you’re in a hurry, and are ready to jump in and protect your plants if we have a mid-May frost, I can’t stop you from planting. You may end up with plants that produce much earlier than mine. Or they may sulk and get diseases and make misshapen fruit. Sometimes the bet pays off, and sometimes it doesn’t. I like to play it safe.
By Erica Smith, Montgomery County Master Gardener. Read more posts by Erica.
I almost always hold off until mid-May, but the long range forecast seduced me into planting my tomatoes this week. We’ll see if the gamble pays off.
Particularly for plants that go deeper such as tomatoes, I dig the hole a week in advance to allow sun and air warm the soil. Back in the day I took the extra step to fill used gallon milk jugs with water, let them warm during the day next to the holes, then put them in the holes at night, removing them next morning. Letting water in a can or pail warm in the sun, then poured into the empty holes serves two purposes – warming the soil and ensuring the bottom has enough moisture.
I was at the Baltimore Farmer’s Market on Sunday. Tomato plants were out. i wanted to resist, but my favorite vendor for tomato plants had Sun Golds. Since I missed them last year, I bought a couple and planted them. I know it’s too early, but for Sun Golds, I’ll have to take my chances. I’ll try to wait on the rest of the tomato plants, but temptation might get the best of me on Sunday.
-3/27/25 -Started Tomato seeds indoors using Gurneys Tray with “Plugs” and heating pad beneath, then under grow lights
-10 each 4 varieties chosen for disease resistance (1 was a cherry variety we like ).
– 4/13/25- Transplanted into 3x3x3 plastic pots (reuse annually) w/commercial potting mix.
– in about 10 days, Beginning to struggle indoors despite Grow lights and some natural light and 1x weekly feedings
-4/23/25 placed outdoors in makeshift cold frame, still weekly feedings – feeling much better in natural light. ” Look” ready to plant out, but want to wait as recommended. What is best to do to keep them “happy” as they begin to outgrow their pots?
BTW__To hedge my bet,( 1/2 were placed in a mower cart and moved into the garage at night, other 1/2 in a typical cold frame,- both groups did OK)
My tomato, eggplant, pepper and Basil transplants moved into my cold frame yesterday. Looking at the 10 day forecast, weather looks promising, soil should be 55 degrees. But as we all know the warm season plants always catch up and planting early can be risky if we get a cool spell.