In the Garden:
Northern California Coastal & Inland Valleys
May, 2012
Regional Report

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Watch out for the arrival of tomato hornworms later in the season! Original watercolor by Kim Haworth.

Tomato Planting Time!

It is usually safe to plant your summer vegetable garden during the first week in May. The days are long and the soil is sufficiently warm to support warm weather crops such as tomatoes, corn, cucumbers, peppers, eggplant, and squash. I know a lot of gardeners who try to get an earlier start on the season. However those of us who are patient usually catch up and have a better yield in the end. Here's why.

Warm season plants need the soil temperature to be consistently above 60 degrees F so that their roots will grow. Night time temperatures should also stay above 60 degrees. But most importantly, warm season crops are usually those that set fruit and require pollination by insects. If it's too cold for the bugs to be out, it's too early to plant.

Cool season crops include non-flowering leafy plants such as lettuce, bok choy and spinach as well as root vegetables such as beets, turnips, and carrots that don't require the help of insects for pollination.

Warm season plants like peppers and eggplant are usually deep rooted and will withstand some drought, but yield may increase with regular irrigation. The deep roots also allow the plants to withstand long periods of higher-than-normal air temperatures. If the soil is too cold when you plant, the roots will stay close to the surface and won't achieve the depth that gives them this advantage during hot weather. The ideal irrigation schedule for deep rooted plants is infrequent and deep watering to encourage the roots to grow deep into the earth.

Planting Tips for Hot Weather
I usually try not to plant when the weather is predicted to get really hot, but we get surprised sometimes. If you have just planted your summer veggies and we get a heat spell, it's very important NOT to overwater, even if the plants seem like they are wilting. What happens is that the new roots can't take up water fast enough to support the foliage. Watering in these conditions will only cause damage to the roots and eventual failure of the plants.

When the temperatures soar it's best to provide some sort of temporary shade so that the young plants don't lose too much moisture through transpiration. Floating row covers or even sheets of newspaper will work, provided you allow for air circulation by propping the cover up with a frame of some sort. Tomato cages laid on their sides, support stakes, or garden tools can be used to make a frame to support the shade covers. It's also important to remove the covers once the sun goes down, and to replace them again if more hot weather is predicted. These unsightly covers will only need to be in place for a few days until the little plants become established and can stand on their own root systems.

We all want our gardens to be successful and our efforts not to be in vain. Follow these tips and I think you will have produce to brag about come harvest time in August.

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