Roots of trees planted above septic system may well damage it


January 09, 2000

Q. We just moved to an older home out in the county that has a septic system with grass planted over it. My brother suggested I plant willow trees to suck up water in the drainage field. I'd rather plant a perennial flower garden. Is it OK to grow anything other than grass in this area?

A. Brother does not know best in this case. The roots from any large tree can damage the underground parts of your septic system. Don't plant anything if there is a foul odor emanating from your drainage field or if it stays excessively wet. These are symptoms of a malfunctioning system. If your septic system has been checked out and is in good working order you can go ahead and plant a flower garden; vegetables would be fine, as well.

Q. My rowhouse has a concrete backyard. I'm envisioning a vegetable and flower garden this summer. Can I build raised beds over the concrete or should I try to remove it first?

A. Yes, you can construct raised beds directly over the concrete pad. They should be at least 8 inches deep. The deeper the bed, the greater the root growth, the bigger the vegetables, the prettier the flowers. Before building your raised beds, drill large holes through the concrete at any spots where water collects after a rain. Fill the beds with a 2: 2: 1 mixture of high quality topsoil, compost and sharp builder's sand.

Q. I'm an organic gardener and refuse to spray toxic pesticides. But I've had problems the past two years with ants in my home. How can I control them organically?

A. Bait stations work very well indoors. The baits contain sugar or a food attractant mixed with a small quantity of boric acid, pyrethrum or some other insecticide. Ant scouts locate the bait and carry it to the nest, where it is shared. Keep pets and children away from the bait stations. Follow the invaders next time to determine how they are getting into your home. Caulk and seal cracks in floors and walls that allow entry.

This Week's Checklist

1. Protect vulnerable trees and shrubs from winter burn by covering them with burlap or erecting a windbreak on the windward side, 18 inches away. Antidesiccants can be applied following label directions. The protective coating may wear off during the winter and need to be reapplied.

2. Prevent fungus gnat problems around houseplants by allowing the top of the potting soil to dry out between waterings.

3. Ticks remain active as long as temperatures exceed 45 to 50 degrees F. Check yourself and loved ones for ticks when hiking on mild winter days.

Garden tips are provided by the Home and Garden Information Center of the Maryland Cooperative Extension. For additional information on these questions, or if you have questions of your own, call the center's hot line at 800-342-2507, or visit its Web site at

Baltimore Sun Articles
Please note the green-lined linked article text has been applied commercially without any involvement from our newsroom editors, reporters or any other editorial staff.