ASK WENDY: Eco-friendly mulch options for rose bushes

Knock Out roses need to be mulched for weed control.

Special to The Sun
Published: Wednesday, January 23, 2008 at 6:01 a.m.
Last Modified: Tuesday, January 22, 2008 at 6:03 p.m.

Q: I live out in the country and have a pest problem in the mulch around my Knock Out rose bushes. I would like to use an eco-friendly weed control other than wood mulch and chemical treatment.

The roses run along my porch and the wood mulch is infested with Asian roaches. I would like to put some type of ground cover around the rose bushes to replace the mulch, however many of the groundcovers I am reading about seem quite invasive. I'm also concerned about adding/deleting needed nutrients for the roses.

A: I think pine straw might be a good alternative. It would keep the weeds down, add to the organic content of your soil, and it comes from local renewable sources. Since it is not as dense, pine needle mulch may not be as hospitable to the small roaches.

I would not recommend growing a ground cover under the roses. Most ground covers are aggressive by definition and may compete with your Knock Outs for water and nutrients.

There is pre-emergent herbicide that is used by rose growers; it contains the active ingredient pendimethalin. This chemical solution is applied one to two times a year, and it will keep the weed seeds from sprouting under the hedge and won't harm rose plants if applied correctly.

Herbicide applications may not be in harmony with your gardening practices, but it would allow you to remove the mulch and the hiding place for the small roaches. Roses are sensitive to post-emergent herbicides like Roundup so always use caution if you are spray weeds in the rose bed.

A no-chemical approach would be to use a light layer of pine straw 1 to 2 inches deep and if weeds sprout through just pull them out by hand. Be careful using a hoe or other mechanical weeder, since roses can be shallowly rooted.

These roaches are attracted to the lights of your home. Use a lightbulb that doesn't attract bugs. They sell them at local hardware stores.

Q: The freeze earlier this month really burnt my St. Augustine lawn. I didn't know this could happen. Now what should I do?

A: St. Augustine grass has pretty good cold tolerance especially if it is tended correctly before winter. Floratam - one of the most popular varieties grown in the Gainesville area - is cold tolerant down to around 20 degrees and that was the low for many neighborhoods in town. If you drive around, you will notice that some lawns are perfectly fine and others do have a brown quality about them.

You didn't mention if the grass was newly installed; we know that turf that is not well established can be injured by the cold. Also, if you had not watered the lawn before the freeze that can have a direct effect on the damage you will see. Well-watered grass will not desiccate as readily during the freezing temperatures.

It is also a good idea not to fertilizer too much with high nitrogen in the fall months. This generates lush new shoot growth that is easily burned. Grass that is stressed by traffic or by growing in the shade will be damaged by low temperatures, too.

In fact, anything that stresses the grass - drought, shade, traffic, scalping and over fertilization - makes it more susceptible to freeze damage. Manage your grass to avoid these stressors and if possible make sure that you use potassium in the last fertilization of the year in September. Research has shown that potassium applied at the rate of  to 1 pound per 1,000 square feet can add to the stress tolerance of your St. Augustine.

When temperatures warm up and the days get longer, your grass should return to its former green self. You may have permanently lost a few patches in the turf that will need to be resodded or plugged in March or April. In the meantime, water the grass every seven to 10 days and plan on resuming the regular care of proper fertilizing and mowing in the spring.

Wendy Wilber is environmental horticulture agent for Alachua County IFAS Extension Service. Contact her via e-mail at

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