Q&A: Tomatoes

A: There are many reasons why tomatoes don't set fruit. It could be because you 've used too much high-nitrogen fertilizer that causes the plant to produce lush foliage at the expense of fruit. If that's the case, switch to a slow-release, all natural nitrogen source such as alfalfa meal or kelp meal.

Failure to set fruit can also be due to blossom drop, which is most prevalent during cool, rainy periods, but it may be caused by lack of magnesium in the soil. To remedy those problems, shake the plant occasionally to encourage better pollination, and apply Epsom salts around the base of the plant.

One of the most common reasons why tomatoes fail to set fruit, especially in the middle of summer, is the heat. Once temperatures rise to approximately 90 degrees, many varieties of tomatoes slow or shut down fruit production entirely and resume production once things cool off a bit.

--Paul James, master gardener and host of Gardening by the Yard