Ciscoe Morris, Seattle Times garden writer, answers questions on getting tomatoes to ripen; tree roots and home foundations; and keeping flowering cherry from suckering.

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Q: The tomatoes on one of my plants haven’t begun to ripen yet. Is there anything I can do to make them hurry up?

A: Remove all blossoms and newly formed fruit. By mid-August, the blossoms will never form a tomato, and newly formed tomatoes won’t ripen. Taking off the blossoms and smaller fruit will encourage the plant to focus its energy on ripening the bigger fruit that remains.

Pinching off the branch ends, or growing tips, in late August may also help by diverting energy from vine growth to the fruit. Drastically reduce watering. This will make your plant think it might die soon, and since the plant’s main goal is to reproduce, it will put all of its energy into ripening the fruit in an effort to produce seed before it kicks off.

Finally, when the weather report forecasts temperatures dipping into the low 40s, harvest any tomatoes that have turned to a lighter shade of green to bring indoors for ripening. Store them at 70 degrees in single layers, not touching each other. That should cause most of them to ripen within about two weeks.

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Q: I have a flowering plum tree that’s 11 years old and about 25 feet in height. The roots are spreading pretty close to the house and I’m worried they might damage the foundation or nearby pipes. Should I be concerned?

A: After working for years as a certified arborist, I have yet to see tree roots damage a foundation. Roots are in search of moisture and nutrients, and they aren’t going to find them inside concrete walls. When roots run into concrete walls, they turn and grow in another direction or along the side of the wall. Even with normal expansion, it’s pretty much impossible for them to exert the kind of pressure required to damage the wall.

The exception is if a tree is planted so close to the house that trunk expansion causes it to exert pressure on the foundation. If that is the case, it’s the trunk, not the roots that causes harm, and the tree should be removed.

Of course, that’s not to say that roots can’t cause trouble. If the search for nutrients leads it into already cracked sewer lines, or under pavement, all sorts of mischief can occur. It’s not the tree’s fault.

Rather than removing the tree, consider replacing old, cracked pipes with modern materials that are practically impervious to tree root problems, or install root barrier material that encourages roots to turn away, rather than grow under walkways.

Q: How do I stop my flowering cherry from suckering?

A: Remember how frustrated the groundskeeper became when he couldn’t outwit the gophers in the movie “Caddyshack”? Well, that’s nothing compared to what I went through trying to stop flowering cherries from suckering when I was director for grounds at Seattle University.

Suckers grow off roots that fan out from the tree. Most experts will tell you that flowering cherries usually sucker if they are stressed (for example, they’re in poorly drained soil, have been hammered by disease or have been pruned too severely).

At Seattle U., however, practically every flowering cherry suckered, including healthy, vigorous, well-pruned, disease-free ones growing in perfect conditions.

It’s obvious they were doing it to torment the living tweedle out of me! We tried everything recommended to make them stop suckering. First, we tried the commercial product called napthaleneacetate (NAA) that you spray after removing the suckers. It was an expensive waste of time. It didn’t even seem to slow them down.

Next we tried cutting heavily suckering roots at the drip line. We spent hours digging and cutting, and all it seemed to do was to stress the trees and make the other roots sucker more. In the end, we gave up and just cut the suckers off in spring and again after they grew back by fall. I left SU in 2002, but I still have nightmares about battling suckers! By the way, I’ll bet you can guess how many flowering cherries are in my garden!

Ciscoe Morris:; “Gardening with Ciscoe” airs at 10 a.m. Saturdays on KING-TV.

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