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Ask Dr. Hort: Sickly laurel oak should be removed

What to plant in shady areas

Q: At our school, we have a problem. Grass won't grow under our oak trees, and the students have their own ideas as to where they can walk. I would like some suggestions as to what ground covers you would suggest to place under the trees to improve the appearance of our campus without annual sodding. Any help you can offer will be gratefully appreciated. We do use sprinklers using reclaimed water.

John L. Suter, Clearwater Central Catholic High School

A: There are many ground covers but none that take steady foot traffic. I suggest you mulch the pathways where students insist on walking. Here are some ground covers that will improve the appearance of your campus, divided into their light requirements.

For very shady areas, consider partridge berry, Mitchella repens; fishtail fern, Nephrolepis biserrata 'Furcans'; or mondo grasses (Ophiopogon spp).

For shady to partly shady areas, any of the liriope family is a good choice. For these areas, you also can use terrestrial bromeliads of assorted cultivars and English ivy (Hedera helix, many cultivars from green to variegated).

For partly shady areas, you could use sword fern, Nephrolepis biserrata.

For areas that receive sun to shade, the traditional Boston fern, Nephrolepis exaltata 'Bostoniensis,' is popular, and for sunnier areas, you can use perennial peanut (Arachis spp.) or Asian jasmine (there are many cultivars such Trachelospermum asiaticum).

Sickly laurel oak should be removed

Q: One of our oak trees certainly doesn't look like the others. A tree man trimmed off a limb and gave the tree a treatment. You can see the "sickness" coming out of where the limb was cut off, according to him. Will the tree come back or should we have it cut down?

Yvonne James, Palm Harbor

A: You have a laurel oak, Quercus laurifolia, in serious decline, which is a hazard and should be removed, for storm season is upon us. The tree is sending out little tufts of growth as a last-ditch effort to stay alive. The only treatment is a chain saw. Always ask for International Society of Arboriculture (ISA) certification when choosing an arborist to better ensure a proper diagnosis and management plan.

Use triclopyr to kill Johnson grass

Q: Could you please tell me the best way to rid a yard of Johnson grass (clumps of tall, slender green grass)? I have tried weed killer, then digging out clumps, but have been unable to get rid of all of it and it keeps coming back.

Marla Hailstone, St. Petersburg

A: Probably the best product for your use would be Garlon 3A. It comes in a 2 1/2-gallon pail through a landscaping supply house like Lesco and it is expensive (about $250). The active ingredient is triclopyr. You may be able to find a stump and brush killer with triclopyr at a home improvement store.

Bougainvillea is a poor choice for an entryway

Q: I have two bougainvillea flanking my front entrance. They grow out of control in the summer and look awful in the winter when the frost hits. I'd like to replace them with something else that won't grow more than about 4 feet tall, will be reasonably hardy, drought-resistant and doesn't need much watering. Do you have any recommendations?

Carla Altman, Land O'Lakes

A: You didn't plant the right plant in the right place. Gardenias, Gardenia angusta (formerly known as Gardenia jasminoides), would give you a nice spring flower show with a beautiful fragrance upon entry. Another choice would be sweet olive (left), Osmanthus fragrans. This winter bloomer has small white flowers, hollylike foliage and a sweet aroma. Or perhaps dwarf Burford holly, Ilex chinensis 'Burfordi dwarf' — a true holly with red berries in winter. These are all hardy, drought-tolerant choices after establishment.

Need help?

Enter Greg "Dr. Hort" Charles, who for more than 30 years educated gardeners through the Pinellas Technical Education Centers. He answers questions about landscape and garden pests. E-mail your questions to drhort@tampabay.rr.com or to features@sptimes.com (put Dr. Hort in the subject line). Mail questions to HomeLink, Features Department, St. Petersburg Times, P.O. Box 1121, St. Petersburg, FL 33731. Describe your problem in full, and include your name, city and contact information. If possible, include a photo. We will print his advice on Saturdays in HomeLink.

Ask Dr. Hort: Sickly laurel oak should be removed 08/13/10 [Last modified: Thursday, August 12, 2010 5:33pm]

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