Bay Area Gardening Q&A: Problems with tomato fruit set

AT. I have an atrium that surrounds one part of my house. I successfully grew tomatoes there last year. This year I planted a plant there, and it bloomed, but did not bear fruit. I followed all your advice (egg shells, worm castings and bone meal) and sprinkled on Blossom Start but the buds just dry up and fall off. Any suggestions?

Carol Meacham, Danville

BUT. I’ve never used “begin bloom” before, so I hope you’ve followed the directions for using it. Since that didn’t work and you’re having trouble, it’s time to take a look at your garden plot as a whole.

The most important thing to pay attention to is whether you are getting enough sun. Tomatoes, unless you grow cherry tomatoes, need 8 hours of sunlight each day. Although you were successful last year, the conditions in your area may have changed. The most common problem is trees that have grown and are now shading your garden.

You also want to check that the tomatoes are getting enough water. Tomatoes do best when they are on a consistent watering schedule. If you don’t have drip irrigation and a timer, you might consider installing one.

If the plants grow beautiful and leafy, then the problem is most likely not in fertilizers. If you add more at this stage, you may encourage more growth, which will reduce fruit production. Heavy nitrogen fertilizer encourages plants to grow more green leaves, and if they do, they don’t put energy into fruit.

Tomatoes are a kind of self-pollinating, aided by the wind. The atrium can be too sheltered, so get in the habit of lightly running your hands over the plants to help pollinate the flowers.

Despite ideal growing conditions, we cannot control the weather. When temperatures rise above 85 degrees during the day or below 55 degrees at night, the plant sheds its flowers and focuses energy on keeping itself alive. We’ve had a lot of temperature fluctuations and I suspect this is the main problem.

I wouldn’t turn down a healthy tomato crop. The plant may just need to take root and build up the root system, and there is still a lot of summer.

AT. We have three large bottle brushes that hummingbirds and bees love. Is there an advantage to cutting them back with the current weakened growth to encourage more growth, or is it better to leave them alone?

Terry and Diane Sullivan, Los Gatos

BUT. While some shrubs need heavy pruning, bottle brush (Callistemon spp.) is not. Too deep pruning can damage the bush, and in some cases even kill it.

Flowers grow on new wood, so you never want to cut too deep into the bottle brush. Instead, cut off the tips of the plants to form a shrub and encourage new growth. If your brushwood has grown too large or has too much dead wood inside, it is best to cut it at ground level.

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