Senorita Rosalita cleome (Photo by Dan Gill)

Virginia Sweets heirloom tomatoes (Photo by Dan Gill)

Butterfly pentas (Photo by Dan Gill)

For Release On Or After 07/25/14

By Dan Gill
LSU AgCenter Horticulturist

Oppressive heat and humidity are part of late summer in Louisiana as much as good food and music are part of our local culture. Despite the heat, garden activities continue for those who can stand it.

Be sure to work in the cooler times of the day, stay in the shade as much as possible and drink water before during and after working outside. Don’t forget to take frequent breaks to cool down.

Fix up flower beds

Forlorn flowerbeds past their prime and overrun with weeds are an all-too-familiar sight in late summer landscapes. Our long growing season and abundance of insect and disease problems generally make it unreasonable to expect all bedding plants to hold up from the beginning of summer in May until its end in October.

Unfortunately, many gardeners give up with the attitude that it is too hot to plant or grow anything now. This is the perfect excuse to simply allow the beds to remain unattractive.

But heat is no excuse for ugly flower beds. You can work during the cooler times of the day, and the nurseries are full of exciting colorful plants that thrive in late-summer heat. It is still worth the investment to purchase and plant summer flowers now. We would expect these plants to provide color until November. That’s over three months of color.

To replant your bed, remove any old bedding plants and put them in your compost. If the bed is badly infested with tough weeds, like bermudagrass, torpedograss or nutsedge (nutgrass, cocograss), you should spray the weeds with glyphosate to kill them and wait a few days until they’re dead before proceeding further. After the bed is cleaned out, turn the soil and incorporate some organic matter before replanting.

Colorful plants that can be planted now include Mexican heather, ornamental peppers, ornamental sweet potatoes, coleus, impatiens, periwinkle, cosmos, globe amaranth, ageratum, salvias, marigold, portulaca, blue daze, perennial verbena, purslane, dusty miller, rudbeckia, narrow-leaf zinnia, Profusion zinnia, Zahara zinnia, caladium, balsam, gerbera daisy, celosia, scaevola, melampodium, butterfly weed, shrimp plant, sunflower and cigar flower.

And don’t forget the Louisiana Super Plants selections and their cousins. They include Serena angelonia and other angelonias, Little Ruby alternanthera and other alternantheras, BabyWing begonia and other begonias, Butterfly pentas and other pentas, Kauai torenia and other torenias, Mesa gaillardia, Bandana lantana and other lantanas, Senorita Rosalita cleome and Luna hardy hibiscus, For more information on the LSU AgCenter’s Louisiana Super Plants program, go to www.lsuagcenter.com/superplants.

Spring and fall vegetable gardens have a lot in common

August is right around the corner, and it’s an important month in the vegetable garden. Many of the same warm-season crops you planted in spring can be planted again for fall production, as well as some of the hardy cool-season crops.

Transplants of tomatoes, bell peppers and eggplants should be planted in August. The fall tomato crop is generally not as good as the spring or early-summer crop, but it sure is nice having homegrown tomatoes in November and early December.

If you still have peppers or eggplants growing in the garden from the spring planting, they will generally produce very well in fall. Stake them if they need support, continue to control insect and disease problems as needed, and provide some additional fertilizer.

Many other vegetables can be planted as seeds in August – either in pots for transplanting later or directly into the garden where they will grow. Vegetables that may be planted from seed in August include broccoli, kohlrabi, Brussels sprouts, cucumbers, cabbage, collards, mustard, lima beans and green beans (choose the bush types, late August), squash and Southern peas (early August).

Expect insect and disease problems and act quickly to prevent extensive damage. Also, watch for dry periods combined with high temperatures and water when necessary. A mulch of leaves or pine straw will help control weeds and conserve soil moisture.

Don’t be your plants’ worst enemy

Grass and weeds grow rapidly in summer, and the string trimmers we use to control them can be very damaging to young trees, which have relatively thin bark. A line that hits the trunk will remove part of the bark with each contact. If you’re not careful, you might even remove an entire ring of bark all the way around the trunk, girdling the tree. This can kill a young tree. Mowers pushed hard or dragged around the base of young trees can be almost as damaging.

To prevent these problems, don’t allow grass to grow close to the base of young trees for the first five years after planting. Maintain a grass-free area at least a foot out from the trunk. A mulch 2 or 3 inches thick spread evenly over the area, but pulled back slightly from the trunk, will help a lot. Tree guards placed around the lower part of the trunk of young trees can also be used to prevent this type of damage.

Rick Bogren