The following gardening questions were submitted by readers. Have a question yourself? Contact gardening columnist Anthony Keinath by email, tknth@clemson.edu.

Q: I have a small garden, approximately 15-by-40 feet. Is there something I can plant this time of year and then plow under that will bring it nutrients?

A: Crimson clover, a winter cover crop that supplies nitrogen, should be planted at the end of October. Another option is Austrian winter peas that can be planted in December.

Q: I want to overwinter two medium-size geraniums. I read online to take them out of the pots, shake off the soil and store in a paper bag in a cool, not freezing, place.

A: Here in the Lowcountry, it is not necessary to take geraniums out of their pots for the winter. I keep mine outdoors but move them into the garage when the temperature is predicted to go below 35.

Q: My lantana has always been healthy, but now leaves have black edging, and they are shriveled.

A: Based on the photo sent with the question, the problem is lantana lace bug, an insect introduced into Florida to control invasive cultivars of lantana. Unfortunately, the lantana lace bug migrated up here and eats common (but not trailing) lantana. Prune damaged leaves. If necessary, spray with any insecticide labeled for lace bugs. Some cultivars, like ‘Dallas Red,’ seem better at regrowing after lace bug attacks than others.

Q: I remember learning years ago the times to weed and feed and fertilize based on certain holidays.

A: Pre-emergent lawn herbicides should be applied on Valentine's Day and Labor Day. Do not apply weed and feed products, as these dates are too early and too late, respectively, to apply fertilizer to any type of Southern turf grass.

Q: I read some time back that using the same amount of fertilizer on St. Augustine and centipede will gradually kill centipede. Is that true?

A: Yes, the maximum rate of nitrogen for St. Augustine, 4 pounds per 1,000 square feet, could harm centipede, as it is twice the rate that centipede can tolerate. Reference the online table ”Lawn Fertilization Schedules for Various Turfgrasses & Geographical Areas of South Carolina."

Q: My homeowners' association has storm water ponds with maintenance problems. Could you advise or direct me on plant information that would help solve algae build-up, bank erosion and plants that would make the ponds attractive.

A: Two fact sheets on shorescaping freshwater ponds: "Shorescaping Freshwater Shorelines" and "Aquatic Shoreline Plant Selection" are available in the Clemson Home Garden Information Center online, hgic.clemson.edu

There also is a fact sheet on blue-green algal blooms on the same website. 

Q: I would like to start a raised bed veggie garden. What types of bagged, ready-to-use material and in what ratio would provide a good growing medium and pH level for general veggies?

A: See Clemson’s Home Garden Information Center Fact Sheet 1251, Container Vegetable Gardening. You may want to modify the recipe by using half of the sand or perlite to reduce the need for daily watering. Large bags of perlite and vermiculite can be purchased online.

Q: You haven’t mentioned bacterial wilt disease on tomato plants in any articles. It is almost impossible to grow tomatoes in my area because of this disease.

A: There are no tomato varieties that are reliably resistant to bacterial wilt. The best solutions are (in order): move the garden; grow tomatoes in pots; add lime to raise the soil pH to 7.5; or grow sweet corn in year one and onions or garlic in year two in the infested area before planting tomatoes in year three.

Q: I have a problem with nematodes in pots with tomatoes and some ornamentals. Can I mix marigold leaves in the soil, or must the marigolds be planted with the other plants?

A: The leaves of marigolds help with some types of nematodes but not root-knot nematode. French marigolds (Tagetes patula) induce nematode eggs to hatch, but the juvenile nematodes can’t infect marigold roots, so they starve to death. A solid planting of marigolds is necessary, so the nematodes can’t survive by infecting other plants.

Q: How are climate zones established?

A: The USDA Growing Zones are based on minimum winter temperatures recorded during the previous 30 years. The zones were adjusted in 2012, and the changes in South Carolina were towards a slightly warmer zone.

Anthony Keinath is professor of plant pathology at the Clemson Coastal Research & Education Center in Charleston. His expertise is in diseases of vegetables. He also is an avid gardener. Contact him at tknth@clemson.edu.