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how warm do containers keep plants?

Posted by kawaiineko_gardener 5a ( on
Wed, May 8, 13 at 21:03

I know that in comparison to growing stuff in the ground,
soil warms up faster in containers than in the ground.

My question is how much warmer is the soil temp and air temps in stuff being grown in containers compared to stuff being grown in the ground?

I know this depends mainly on what type of containers are being used; mine are made of plastic; for colors they are white, gray/silver, red, and blue.

The main reason I ask this is cause I want to do early direct sowing for cold weather stuff; they like cold weather, but cold temps (in 60's or below) will cause slow germination, which defeats the purpose of growing them at this time, which is to get an early harvest.

Would the soil temps and air temps in containers provide enough of a 'boost' in temps that it will result in faster germination?

I also wanted to know if in comparison to stuff being grown in the ground does stuff in containers grow faster and/or do you get an earlier harvest?

Follow-Up Postings:

RE: how warm do containers keep plants?

K...good question. My feeling is: the container color (light or dark) has a lot to do with how much heat is absorbed.

RE: how warm do containers keep plants?

When I have a question like yours, I eliminate all the variables by sticking a soil thermometer in the container and the ground and read what it says. Al

RE: how warm do containers keep plants?

Could you germinate inside and then move outdoors? I've germinated lettuce and other greens indoors (72F) quite quickly. Just put container planted with seeds near a window and loosely cover with plastic wrap. Move outside (after hardening off) once seedlings have a few true leaves.

RE: how warm do containers keep plants?

Containers can be incredibly hot depending upon sun exposure, container size, and how the container is sited (on risers versus sitting on a slab of blacktop). From what I recall, the color of a container doesn't offer as much of an advantage as I'd previously thought....a white container was only 5F degrees cooler than a black pot...if I'm remembering rightly.


RE: how warm do containers keep plants?

Do the color test for heat on a car lot like I did some time. Hold your hand on different shades of cars...amazing!

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