New formulation of herbicide isn't safe in vegetable gardens

Backyard Q&A

April 17, 2005|By Jon Traunfeld and Ellen Nibali | Jon Traunfeld and Ellen Nibali,Special to the Sun

How safe is the herbicide Roundup in vegetable gardens?

This has become a tricky issue. In the past, Roundup was approved for use on vegetable gardens under certain conditions because it contained only glyphosate, which was deemed safe to use around food plants. New versions of Roundup, however, contain diquat or other chemicals, plus glyphosate. These new formulations, such as Roundup Plus, are not safe to use in vegetable gardens. Gardeners are not alerted to this change on the front of the new label. Therefore, you must check the label carefully before applying. Gardeners who inadvertently apply Roundup Plus may have to wait a year before their garden is usable again.

Keep in mind that any toxic chemical, even when approved for use on food plants, can still have detrimental effects on soil microorganisms and should be used judiciously. We generally don't recommend using chemical herbicides in food gardens.

I started tomato plants from seed probably too early, and now I have 15 plants growing under fluorescent lights. How big can I let the plants get before I need to put them in bigger pots? I plan to plant them out the first week of May.

At this point, you want to develop a healthy root system on your tomato seedlings. You can slip the plants out of their container to examine the root system. Crowded roots or leggy plants outgrowing their containers indicate it is time to move them into a larger container. Transplant into containers one size larger than what they are growing in now (probably a 4-inch-by-4-inch container would be sufficient). Plant them deeper in the new containers to encourage root growth from the stem. Keep the lights right on top of the plant tops to discourage legginess. Don't fertilize if the mix you're using has fertilizer in it. You may need to repot a second time to an even larger pot.

You can grow a very nice tomato transplant in just six to eight weeks indoors.


1. Protect early-planted tender annuals, such as zinnias, basil and tomatoes, from late frosts. You can use paper bags, cardboard boxes, quilts or plastic.

2. Spray grapevines susceptible to black rot with a protectant fungicide before and after bloom.

3. Cover broccoli, cabbage and other cole crops with a floating row cover to prevent caterpillar feeding.

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