Brandi Keller and Paul Winsky, extension workers and horticultural experts from Texas A&M, answer readers’ questions about gardening.
Q: I need to cover a 625 square foot area in my backyard with grass. It is now under a large oak tree with bare soil. I’m thinking of St. Augustine. Can I plant turf in the winter? Which type of St. Augustine is best?
A: St. Augustine is the most shade tolerant warm season turf grass, but it still needs 4 to 6 hours of sun. This turf is perfect for the warmer months. Mid-April is the right time. ‘Lorry’ is the norm in our area, while ‘Palmette’ tolerates shade. St. Augustine should be cut to a minimum of 3 inches tall. This is usually longer than most grasses can tolerate, but more leaves on the lblades means more photosynthesis/food.
Be aware that large oak trees do not make an ideal habitat for turfgrass. We have aesthetics in mind and allowing the grass to die under the trees rarely fits in with the image of a beautiful landscape. I would like to challenge myself to accept the conditions and beauty that trees offer.
Large established oaks provide more shade as they age. They grow shallow roots that draw water from surrounding plants. These conditions naturally reduce the success of turfgrass.
You can have a professional Aboriginal grow the branches thinner to let in more sunlight, but be careful not to thin the canopy too much.
Consider replacing the lawn with a shade-tolerant groundcover or landscape bed. Asian jasmine (Trachelospermum asiaticum), holly fern (Cyrtomium falcatum), and vinca (Vinca minor) are all shade-tolerant options.
Q: How to identify and control this weed? It occupies and spreads out on the bare lawn of St. Augustine.
A: Lespedeza (Kummerowia striata) is a warm season annual weed that grows in dry compacted soils.
Non-chemical control includes proper lawn maintenance. A healthy, thick lawn can prevent infestation with regular mowing and proper fertilization. Do not over water the lawn. It prevents the lawn from developing a deeper root system, creating opportunities for thinning and weeding.
For chemical control, use a post-emergence herbicide once the portulaca is identified in the spring. Look for active ingredients like metsulfuron, thiencarbazone, and dicamba. Follow the manufacturer’s label for instructions. More on weed identification: Aggieturf.tamu.edu
Brandy Keller
overwintering potted plants
Q: I have 4 aloe vera plants in the ground (not potted). What’s the best way to overwinter them and what if there is frost/freezing?
A: Make sure there is enough soil moisture before freezing. There are two options for plant coverage:
Cover with a sheet or blanket. Use blankets, pins, or planks to hold the blanket in place and keep it from blowing away. Trapping heat from the ground helps protect plants.
Invert a large pot over the plant. Add weights to keep it from being blown away. If freezes are expected, this will be a quick and easy solution.
Q: I’m seeing black spots spreading on my aloe vera plant and I don’t know what causes them or how to deal with them. Any advice?
A: There are several possible reasons for the black spots on aloe plants.
1. Bacteria — It usually appears on plants as water-soaked lesions. If you cut a tissue and put it in water, the bacteria will flow out of the cut.
2. Anthrax (Colletotrichum sp) — The spots tend to be sunken and may take on a dry appearance as they progress.
3. Physiological — For some reason, with excessive moisture, anthracnose-like spots are observed. This usually occurs when there is irregular watering. Your best bet is to repot, monitor watering, and allow regrowth.
If one or two are suspected, submit samples (detached leaves) to the Plant Diagnostics Lab on the Texas A&M campus, plantclinic.tamu.edu/, for pathogen recovery and diagnosis.
Paul Winsky