Root growth in cold climates

Root growth of seedlings, cuttings, and potted plants can be severely limited when temperatures are low. It’s been cool here with temperatures being mostly 40s to 60s and will continue for the next week so I was concerned about cuttings and seedlings.
Some information I found.
Hardy evergreens: little or no root growth for soil less than 6C (43F)
Peach: little or no root growth for soil 11C(52F) gradually increasing to max at 22C(72F)
Tomato: little or no root growth for soil 15C(59F), best soil 20C(68F) to 25C(77F)

Depends on the plant. I recently transplanted a haskap and a saskatoon. Both plants were beginning to green up, both plants had some of their roots still in a layer of ice.

“hardy evergreens” covers a huge range.


True. The concern is that at low soil temperatures the plant my be alive and even growing but the roots will not grow. That a problem for seedlings and rooted cuttings that need to have their roots growing quickly.


You can cover the soil with 4ml clear plastic.
Gain 6-7 degrees.
Problem is that the weeds underneath it will grow.

I’d like to get my tomato seedlings into the ground but my soil temp is currently 59 and high air temps will only be 60s for the next week. I need to get soil temp up to 68 so as you suggest ill but down plastic to warm up soil.

I would just keep them in a large black pot for now. The tomatoes would experience more growth in the sun heated pot than in the colder ground.

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