Here in the South, transplanting a delicate tomato or fig plant into a standard, black industry pot can often spell doom for the tender young plant. If that black pot is placed in direct sunlight for a significant amount of time, it can dry out really quickly. I’ve had to water 5 gallon buckets with plants in them twice a day in the heat of summer. How much more a tiny 1 gallon pot baking in the sun?

But there’s more danger in such a small pot – excessive heat. Some plants do not tolerate soil temperature fluctuation or high temps. It is easy to cook your plants to death. I decided to paint some of my pots to reflect some of the solar energy that dark colors absorb. Since I have a thermometer, I measured the results.

Its far from scientific, and I had only two examples each of black and light pots. Each was filled with pre-moistened growing media and placed in direct morning sunlight for half a day. I used an instant food thermometer that has proven to be very accurate, and took multiple readings from each pot. I measured the temperature in the middle of the pot and within 1 inch of the edge.

Here the soil in the middle of the back pots hovers around 92.

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However, near the edge it gets up to 114. My other pot, which I failed to photograph, broke 124 degrees.

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The painted pots are about an 80% in value on a scale from black (0%) to white (100%). There is an average 15 degree difference between the two pots when temperatures are measured near the edge of the soil. The lighter color makes a relatively big difference and may preserve plants from heat stress. There was little difference in temperatures when measure in the middle of all pots.

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If you cannot find white pots, paint is a cheap alternative. I used latex indoor house pain that we had lying around. The pots will chip and peel, but I can easily re-paint the next time I use them.

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If you have similar experiences or better ideas, please comment.

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