Richard Bogren, Gill, Daniel J. | 4/19/2018 8:05:17 PM
By Dan Gill
LSU AgCenter Horticulturist
(04/20/18) As May approaches, we transition from the warm days and cool nights of spring and early summer to the hot days and warm nights that will be with us until September. With the increasing heat, you should be noticing the inevitable decline of your cool-season bedding plants.
Now is an excellent time to plant warm-season bedding plants that will brighten your landscape all summer long. Whether replacing cool-season bedding plants with warm-season bedding plants or planting them in an empty or new bed, you should make a few decisions before you head out to the nursery.
First, decide where you want colorful flower beds in your landscape. Flowers are beautiful but are a high-maintenance part of our landscapes. Make sure you do not put in so many flower beds that they become a burden on you as you maintain them through the heat of summer.
Color powerfully draws the human eye and demands attention. Never try to beautify something unattractive by planting flowers around it. You will simply draw attention to something that should be ignored. Around the front entrance of your home, near outdoor art and around outdoor living areas are good spots.
Next you must determine the growing conditions of the areas where you intend to plant the bedding plants. In particular, note the sunlight the bed receives; this is critical in selecting the right bedding plants for the area. The terms full sun (eight hours or more of direct sun), part sun (about four to six hours of direct afternoon sun), part shade (about four hours of direct sun in the morning) and shade (about two hours of direct morning sun or dappled light through the day) are used to distinguish various light conditions. If you have full sun to part sun, choose from the sun-loving bedding plants at the nursery. For beds that receive part shade to shade, choose shade-loving bedding plants.
Look at the size of the area to be planted and try to estimate how many plants you will need to purchase. On average, bedding plants are spaced about 8 inches apart. Keep a record from one season to the next of how many plants are used in a bed to make this process simpler.
Also, consider the desired heights of the plants you will use. You can use plants of various heights; generally taller to the back of the bed and shorter to the front. Decide how tall the tallest plants should be before you go to the nursery.
Decide on a color scheme, too. It’s flabbergasting that gardeners who take the time to choose which colors to combine in their living room will grab anything in bloom at the nursery and plant them together in a flower bed.
No one can tell you what colors you should use together in your flower beds — you know what you like. The point is to think and consider which colors you think will look good together. Generally, avoid purchasing bedding plants in cell packs of mixed colors so you have control over which colors you will combine.
Prepare your beds carefully before putting in the summer bedding plants. A common mistake is to remove the faded plants, half-heartedly turn the soil and then plant the new plants. We must give back to the soil if we expect each new planting of bedding plants to do their best.
First, remove any weeds or other unwanted plants from the bed. Use a herbicide, such as glyphosate, or dig them out by hand. Turn the soil to a depth of about 8 inches. Spread a 2-to-4-inch layer of compost, rotted leaves, aged manure, finely ground pine bark or peat moss over the bed, and then evenly sprinkle a light application of a granular all-purpose fertilizer. Or use your favorite organic fertilizers. Thoroughly blend the organic matter and fertilizer into the bed and rake it smooth, and you’re ready to plant.
Bedding plants are commonly purchased in cell packs and 4-inch pots, but these days you can even find them offered in gallon containers for those who have the budget to indulge in instant gratification. Make sure you plant the transplants into the bed no deeper than they were growing in their original container.
Transplants in cell packs are the most economical, and planted this early in the season they have plenty of time to grow and produce spectacular results. For larger transplants, choose 4-inch pots, but expect to pay several times more per plant. Sometimes it’s worth it, especially for tender perennials grown as annuals, such as pentas, blue daze and lantana, which are generally only offered in 4-inch or larger pots.
Tender perennials grown as annuals are especially good for Louisiana summer flower gardens. They have the strength and stamina to reliably last from now until October or November, when you will replace them with cool-season bedding plants. These are marked with an asterisk (*) in the lists below.
Warm-season bedding plants for sun to part sun: abelmoschus, ageratum, alternanthera, amaranthus, *angelonia, balsam, *blue daze, celosia, cleome, *coleus (sun-tolerant types), coreopsis, cosmos, *dusty miller, gaillardia, gomphrena, *lantana, marigold, melampodium, narrow-leaf zinnia, *ornamental pepper, *ornamental sweet potato, *periwinkle, *pentas, portulaca, *purslane, rudbeckia, *salvia, *scaevola, sunflower, tithonia, torenia, verbena (hardy perennial types), zinnia (especially Profusion and Zahara zinnias).
Warm-season bedding plants for part shade to shade: balsam, *begonia, *browallia, caladium (perennial tuber), cleome, *coleus, *impatiens, *pentas, *salvia, torenia.
Henna coleus is a Louisiana Super Plant that grows in full sun to part shade. This tender perennial is treated as an annual in Louisiana. LSU AgCenter file photo by Allen Owings
Melampodium is a warm-season bedding plant that does well in sun to part sun in Louisiana flower gardens. Photo by Rick Bogren/LSU AgCenter