SalemNews.com, Salem, MA

Q: I have several lilac bushes that sat in 6 inches of water during the 2006 Mother's Day flooding. It took approximately five days before the water receded. The leaves on half of the bushes turned brown and fell off. This spring, two bushes produced about 10 percent of their normal foliage, mostly at the top. I pruned here and there where the branches looked completely dead. They are 7 feet tall and an eyesore. What are the odds that these plants will recover? I have invested much time and energy and will wait another growing season if you think they will come back. Should I give them another year and see what happens or just take them out?

A: I'm a plant-saver! Seven-foot-tall lilacs are irreplaceable, and I think they would be well worth another season's wait. I know it will be painful for you to look at dead branches for another year, but be very careful with what you prune until you're sure it's dead.

Flooding will certainly destroy roots. While a week doesn't seem like enough time to kill the plants, remember that the ground remained saturated for days after the water drained off. My vote would be to wait until next spring to make your decision.

Q: I am in the process of repotting my mandevilla, and I am not sure what to do. I took it out of the large pot it has been in for two years. I wanted to put some new soil in. When I washed the old soil off the roots, there were so many tubers attached to the plant that I didn't know whether to pull any of them off or just repot the plant as is. I would appreciate your advice.

A: There's no need to remove the tubers. However, there is some debate over whether new plants can be grown from the tubers. It might be worth a try if you're game. If you do attempt it, be sure there are several eyes on each tuber. Otherwise, leave the tubers alone. Tubers store food, and the plant is obviously healthy and using them.

You are doing a very complete and thorough job of repotting by taking the time to rinse the roots. I admit I would have just removed the plant from the pot, shaken off any excess dirt, loosened the roots, if necessary, and replanted it in fresh bagged soil, perhaps giving it a larger pot. Your method, though, should show superior results later in the summer when the plant blooms.

Q: As a beginning gardener, I went to a nursery to buy some mulch for my young lilac trees only to be confused by the many types available - pine, dark mulch, spruce, hemlock, cedar and some red dyed types. I knew I didn't want mulch that had red dye in it because I assumed it would not be good for the environment. Could you enlighten me on the differences with mulches? Are price and color the only considerations?

A: Wood mulch is used to hold the moisture in the soil and control the soil temperature. (Your lilacs will appreciate it.) Mulched beds are slower to warm up in the spring and slower to cool down in fall. As you mention, there are differences between the kinds of mulch you see at the nursery, price being just one of them.

Most of the wood mulches are colored, and come in a variety of hues to match your house and even your eyes. Mulches are also colored red, brown or black for gardeners who want a natural, uniform color that looks like rich composted material. Colored mulch does hold its fresh look longer than naturally colored wood mulch. The dyes used are generally safe, but read the bag or ask to be sure. Most dyes on mulches won't rub off on clothes.

If you choose to use colored mulch, be sure to buy enough to cover the given area so the color will be consistent throughout your yard. How much should you buy? Use this equation - multiply the length of the area in inches by the width, then multiply by four (to allow for a four-inch depth). Take these figures along when you buy the mulch.

Mulches are available in many size chips and chunks as well as shredded varieties. Mulch that is fine will decompose faster and is more apt to blow or wash down a hilly area than a larger chunk. But a larger chunk might float away in a very wet area. Ask to see a sample of the mulch before you buy it.

Bags that are labeled "bark mulch" must contain 85 percent of the stated material - cedar, pine, cypress, etc. Bags labeled "mulch" have to be only 70 percent of the stated variety. Here are a few types of mulch that are available:

Pine bark: For general landscaping and garden use. Pine bark tends to hold its color better than other mulches and it smells good, too. It's probably the cheapest and most commonly available mulch in the Northeast.

Red cedar is light brown and smells wonderful, like a cedar closet.

Cedar chips are coarser than cedar mulch, and are good for paths and play and picnic areas. Chips are cheaper than mulch.

Cypress is from the deep South and lasts longer than other wood mulches. It is light in color.

Mulch is sold by the bag or, more economically, by the cubic yard. Have it delivered by the truckload and share it with a neighbor for real economy.

Colored mulch may fade after a year or two, and can be restored by replacing the mulch completely or by adding a fresh layer to the top. A light raking will often restore a new appearance to a mulched bed as well.

Be sure to water the area well before or immediately after applying mulch. Otherwise, the mulch could form a barrier to needed water or soak water away from the plants, just as a layer of dry peat moss will.

Termites are attracted to wood fiber, so if you have trouble with termites, keep wood mulch at least one foot back from wooden buildings. Some gardeners put down a termite barrier in the space between the mulch and the building. Generally, termites prefer a larger chunk of wood, not shredded mulch.

This week's dirt: We're more than halfway through the grass-growing season. Have you sharpened your mower blades lately? By now, they need it. Dull blades tear the grass, and grass that is torn rather than sharply cut will look yellow/brown a few days after mowing instead of a healthy green.

And continue cutting high during hot weather for the health of your grass. Don't remove more than one-third of the grass blade in a single cutting.

nnn

North Shore Gardener by Barbara Barger of Beverly is a regular feature of the Home North section. Reach Barbara by e-mail at nsgardener@comcast.net or write to her c/o Essex County Newspapers, 32 Dunham Road, Beverly, MA 01915.