Q: I work in a garden center. A customer believes that we "train" our plants to need water every day because we water them regularly. Is this true?

Walter Reeves / Special (ENLARGE)

Tomato seeds must be fermented before they are stored for planting the next spring.

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PHILDA STARKS, e-mail

A: The plants were "trained" long before they came to you. In moist soil, plants take what water they need and leave the rest. If surplus water keeps the roots soggy, they get root rot and die. Greenhouse growing media are very fast-draining because growers don't want to fight root rot. Therefore, at the garden center you have to water often because your plants dry out quickly. Normal soil doesn't dry nearly so fast, so homeowners should water their plants sparingly the first week or two, to allow the roots to acclimate themselves to the new drainage conditions. In this case, it's the homeowners' responsibility to "train" their plants, not yours.

Q: Why do some people paint the trunks of trees white? A neighbor recently did this to three large trees in their front yard. I have seen this in the countryside and guessed it was to reflect light so cars on a dark country road would not crash.

LEN BROWN, Chamblee

A: Pecan farmers sometimes paint the bottom of their trees white. When the trees are young, the southwest side of the trunk becomes hot on sunny January days. When temperatures drop at night, unprotected bark will crack. The white paint prevents heat buildup and averts tree damage. Old-timers also believed that white paint would repel bugs by confusing them. I think most white-painted trees you see in the countryside are decorated because the owner thinks it looks cute or old-fashioned, not for traffic signals.

Q: On your radio show you mentioned fermenting tomato seed in order to save them for next year. Can you provide details?

JOEY TATE, e-mail

A: Tomato seeds are each surrounded by a jelly capsule that inhibits germination. To remove the jelly, scoop the seed you wish to save into a glass jar and half-fill with water. In a few days the water will be covered with a thick mat of mold. Five days later, fill the jar with water, cover and shake gently. Allow it to sit for an hour. Viable seed will sink to the bottom of the jar while mold and debris will rise to the top. Pour off everything except the good seed and rinse a few times with fresh water. Put the cleaned seed onto a Styrofoam plate and allow to dry thoroughly. Store in a cool, dry place until next year.

Q: I have some Styrofoam packing. Can I break it up and mix into garden soil to make it lighter and easier to drain? I know potting mix has Styrofoam mixed in already.

SAMANTHA TAYLOR-BRADY

A: The white balls in potting soil are perlite, not Styrofoam. Perlite is made by superheating a glassy rock that occurs in the western U.S. as well as in other parts of the world. The rock contains water, so when it is heated, it expands like popcorn. Because perlite is very porous, it holds moisture and nutrients. Styrofoam is not porous and it tends to float out of soil and blow in the wind. You are welcome to try it, but I think you will be disappointed.

Listen to Walter Reeves Saturday mornings on WSB-AM (750) from 6 to 10. Call 404-872-0750 or e-mail georgiagardener@yahoo.com to ask questions. Tune in to Walter on "Gardening in Georgia" at 7 p.m. Thursdays and 12:30 and 6:30 p.m. Saturdays through October on GPB.