Q. I have a 5-year-old Wonderful pomegranate bush that is approximately 5 feet tall. Every spring, the bush has approximately two dozen beautiful red flowers, which then fall off.

Consequently, I have never had any fruit from this bush. What can I do to get some fruit?

Peter E., Danville

A. The primary reasons pomegranates don’t produce usually has to do with water, pollination, sunlight and maybe a little about fertilization.

Pomegranates are drought resistant, but to set fruit, they need additional irrigation. Next spring, when the buds appear, increase the amount of water that you’re giving the tree. Pomegranates also do much better when planted in a hot, sunny spot.

If you’ve done all that, and you’re still not getting fruit, the problem might be with pollination. Planting a second tree nearby will increase the cross-pollination, and increase your chances of getting some wonderful fruit.

Pomegranates don’t require a lot of fertilization, but they can benefit by adding a little 10-10-10 fertilizer, mulching the area beneath the tree and pruning to let more sunlight into the interior of the tree canopy.

Q. I don’t have a lot of sun in my backyard, but I do have one sunny patch where I plant my tomatoes every year.

My daughter-in-law informed me that I shouldn’t be growing tomatoes in the same spot year after year. Is she right? Should I only grow tomatoes every three years? I don’t like that idea.

MaryLou, San Jose

A. Your daughter-in-law is correct. You need to rotate your crops to avoid growing certain plants — tomatoes, potatoes, eggplants and peppers — in the same soil season after season. The primary reason is that you could be introducing soil-borne diseases, primarily blight, into the soil, which will ruin crops for a long while. Think the Dust Bowl meets the Potato Famine.

That’s not easy to do in a small garden, but even moving the plants over a few feet can help.

If you absolutely can’t rotate your crops, be sure to return a lot of amendments and nutrients to the soil and grow cover crops, such as fava beans, during the winter to put nitrogen back into the earth.

You also can reduce the risk by growing varieties that have been bred to be disease resistant. None of this will prevent all disease, but it will slightly reduce the chances.

In the “off” years, you can try growing tomatoes in pots, placed in the same sunny area. You can grow other produce in the beds around the pots to keep the soil healthy and active.

You also can look for smaller tomato varieties that will produce well in less sun. The larger the tomato, the more sun it needs, but there are smaller patio and cherry tomatoes that produce well in shaded areas.

Gardening webinar

Having issues with your vegetable garden this year? Bring your problems and your questions to our upcoming Flora + Fauna webinar on “Vegetable Gardening: What Went Wrong” at 10 a.m. Thursday, July 15. Master Gardeners will do their best to help you troubleshoot. The webinar is free, but you need to register at extras/mercurynews.com/events.

Have a question about Bay Area gardening?

Use this form to submit questions. Photos should be mailed separately to jmorris@bayareanewsgroup.com.