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Beets like cool weather, but

Beets like cool weather, but they can take some heat and it's not that hot in San Francisco right now. With a shade cover (an old bedsheet), they should do OK. Or, you can plant again in the fall when the weather is cooler. If you have lush green and small bulbs, this is usually due to too much nitrogen in the soil. Make sure you have loose soil with lots of compost mixed in. And they may need more water.