Lantana can be a colorful addition to a late-summer landscape. (Photo by Dan Gill)

Many retailers have a variety of plants available that can be used to freshen late-summer flower beds. (Photo by Rick Bogren)

For Release On Or After 08/01/14

By Dan Gill
LSU AgCenter Horticulturist

If you want to boost the color in your landscape now, don’t let the heat stop you. Nurseries have excellent selections of colorful bedding plants that will thrive in whatever heat summer throws at them. These plants come in a variety of heights, textures and colors, and are adapted to grow in everything from moist, shady areas to hot, dry, sunny locations.

It’s generally worth the investment to plant warm-season bedding plants as late as August, given that these plants will stay attractive until November.

You can create cool, elegant color schemes with pastels, or an explosion of bright, vibrant colors full of excitement. Bedding plants can be used in flower beds, mixed borders, containers and hanging baskets to provide the color you crave wherever you want it. Really, Louisiana gardeners are not greatly limited at all by hot, summer growing conditions, as long as they use the proper plants.

There are a variety of reasons you may want to plant colorful bedding plants now. Our long warm season, which lasts from May to October, is longer than many annuals can stay attractive. After months of blooming in your garden, these plants just run out of steam in late summer and begin to look tired. Petunias, cleome, cosmos and balsam are good examples.

Insects and diseases can also take a heavy toll by late summer. The loss of plants to insects or diseases can leave empty spaces in your flower beds. You don’t have to look at these gaps until it is time to plant cool-season bedding plants in October and November. You can replace what has been lost to pest problems with new heat-tolerant bedding plants now.

Or, you may decide you want to brighten up your deck, porch or patio with large pots or hanging baskets full of colorful bedding plants. This is a great way to add color to outdoor living areas without the labor involved in preparing new beds or getting existing beds in shape for planting.

Preparing beds

To replant your flower beds, first remove the old plants and put them in your compost pile. Avoid composting any weeds that have set seeds. Dig them out and throw them away. You could also spray the weeds with glyphosate herbicide (various brands) to kill them before removing them. This is especially recommended if you are dealing with tough weeds, such as bermudagrass, torpedograss or dollar weed.

Next cover the bed with a 1-to-2-inch layer of organic matter, such as compost, bagged or aged manure, landscape soil conditioner, grass clippings or peat moss. Sprinkle about one-half cup of 15-5-10 fertilizer per 30 square feet (or any general-purpose fertilizer following label directions) over the organic matter. Then, thoroughly incorporate everything into the soil. Rake it smooth, and the bed is ready to plant.

Try to do this work early in the morning or late in the afternoon when temperatures are cooler, and drink plenty of fluids. The heat is no reason not to refurbish your flower beds, but you should still be careful when working outside while the temperatures are high.

What to plant

When planting late in the growing season, make sure the plants you purchase are healthy and vigorous and have been properly cared for. Avoid plants that look wilted or leggy, have poor color or show signs of insect or disease problems. This is not the time of year to nurse struggling plants back to health. Start off with the highest-quality plants you can find.

There are lots of choices for planting now. For sunny beds or containers, choose periwinkle, melampodium, alternanthera, angelonia, blue daze, purslane, portulaca, pentas, torenia, perennial verbena, salvia, sun-tolerant coleus, lantana, zinnia, marigold, gomphrena, cosmos or celosia. For shady and partly shady beds and containers, choose impatiens, torenia, begonia or coleus. You’re likely to see other great choices available at the nursery as well.

When planting transplants, we often rip or pull apart their roots slightly if they are root bound. This is done to encourage the roots to grow into the surrounding soil and help the plant get established. But I caution against doing this when planting this time of year. Plants’ roots must absorb water rapidly to supply their needs when temperatures are hot, and transplants will not be able to tolerate such damage to their roots now.

Mulch with an inch or two of your favorite mulch and water the bed thoroughly when you finish planting. The mulch is important to prevent weeds and minimize watering. Watering is the trickiest part of planting this time of year. You may need to water the bed fairly frequently until the plants send roots out into the surrounding soil. Watch the plants carefully for wilting, and water when needed.

If you don’t feel up to replanting flower beds at this time, you can still improve the appearance of your landscape. Remove the old, unattractive plants, control the weeds and then apply a thick (at least 4-inch) layer of mulch over the area. An empty but clean and mulched bed is far more attractive that one full of weeds and struggling flowers. The heavy mulch will keep the bed weed free and ready for you to prepare it and plant cool-season colorful bedding plants in late October or November.

Rick Bogren