Q How much should I trim my tomato plants? Some are in the garden and some are in pots.

A How much to trim tomato plants -- and even whether to trim them at all -- depends on whether they have an indeterminate or determinate growth habit. (The seed packet or plant label should indicate this.)

Most tomato plants are indeterminate, which means they continue to grow taller all summer. You often see indeterminate tomatoes pruned to one main stem, which is tied to a tall stake. This keeps fruit and foliage off the ground and allows for good air circulation, which in turn, keeps the plants healthier. But it also removes much of the potential foliage, leaving the fruit more vulnerable to sunburn, and reduces the plant's total yield.

A better solution is to remove most, but not all, of the suckers so there are two or three strong, upright stems, which produce more leaves and ultimately, more tomatoes. To trim an indeterminate tomato, cut most of the sucker growth (the young growth that develops in the axils or crotches between the main stem and the leaves or branches) until the plant has only a few stems.

Determinate plants grow several feet tall, then fill out, rather than continuing to grow upward. Determinate plants often are grown in cages for support. They typically need no trimming, except for the few leaves that might droop down and touch the soil, which makes them more susceptible to fungal diseases.

Determinate tomato varieties will be easier to manage in containers, but you can grow any tomato variety in a container if it's large enough and has drain holes. (A container that's too small allows the soil moisture to fluctuate widely, making tomatoes more likely to develop blossom end rot.)

What, no pawpaw? Q I'm a recent transplant to Minnesota and wonder if I can grow two of my favorite fruit trees here: pawpaw and persimmon.

A Unfortunately, neither the pawpaw (Asimina triloba) nor persimmon (Diospyros virginiana) can be grown successfully here. You might keep a persimmon tree alive in a very protected location, but it wouldn't produce fruit.

If you want to grow small trees that will provide fruit, at least every few years, try Sungold and Moongold apricots. Two sour pie cherries do well here also -- Northstar and Meteor. Beyond that, there are several reliable plum and apple trees that produce tasty fruit and bloom beautifully each spring.

Controlling quackgrass Q Help! How can I control quackgrass?

A It's easier to control, even eliminate, quackgrass in a garden than it is in the lawn.

Gylphosate (sold as RoundUp) kills quackgrass, but it also kills surrounding flowers, vegetables and grass.

It's almost impossible to pull quackgrass out of the lawn because its roots become entangled with those of other grasses. Even if you do get some of it out, the parts left in the ground will sprout anew.

If you see small tufts of quackgrass in your lawn, you can spot-treat with glyphosate. The surrounding grasses should fill in the area killed by the glyphosate. If there are larger patches of quackgrass, treat the entire patch. Then, once you're sure it's dead, dig out the patch and reseed or resod so more weeds don't move in.

If quackgrass is running through the entire lawn, about all you can do is mow very, very frequently -- as soon as you see the quackgrass is a little taller than the surrounding grasses. Frequent moving won't harm your slower-growing turfgrasses, but it will weaken the quackgrass and eventually it will diminish, and, it is hoped, disappear.

In a garden, you may be able to pull up long runners of quackgrass when the soil is damp and a little soft. If it's growing in among your plants, you can carefully daub glyphosate directly onto quackgrass leaf blades without getting any of the material on your flowers or vegetables. (The chemical will move internally down into the quackgrass roots and eventually kill them.) You may have to do this several times if it resprouts.

To apply glyphosate directly to the weed leaves, attach a small sponge to a stick and dip the sponge in a jar of herbicide. You also could put on a rubber glove and a cotton glove on top of it. Dip your fingers in the herbicide and simply wipe the quackgrass leaves with your gloved hand.

Deb Brown is a garden writer and former extension horticulturist with the University of Minnesota. To ask her a gardening question, call 612-673-7793 and leave a message. She will answer questions in this column only.