Louisiana summers are long, hot, and humid. Temperatures during the summer months from mid-June to mid-September average 90 °F or more with overnight lows averaging above 70 °F. We do have many subtropical characteristics because of the Gulf of Mexico and may experience strong isolated showers, tropical storms, and even hurricanes.
Even in the summer chores in the garden continue. Try to work outside in the early morning, before 10 am, or the late afternoon, after 3pm, when the temperatures are cooler. Keep hydrated with plenty of cold water, stay in the shade as much as possible, wear a hat that shades your face, ears, and back of your neck, and wear loose, comfortable clothing, use sunscreen. Finally, take frequent breaks.
- Control thrips, aphids, cucumber beetles and spider mites on roses by using a recommended insecticide or miticide. Also continue blackspot control by using a recommended fungicide at seven-to-10-day intervals.
- When irrigating, water the soil area thoroughly. Try to irrigate less often, but irrigate well each time. Light, overhead sprinkling is not the best way to water.
- Continue to plant warm-season bedding plants such as Mexican heather, ornamental peppers, ornamental sweet potatoes, angelonia, coleus, impatiens, periwinkle, cosmos, begonia, pentas, globe amaranth, ageratum, salvia Victoria, marigold, portulaca, blue daze, perennial verbena, purslane, dusty miller, rudbeckia, abelmoschus, narrow-leaf zinnia, Profusion zinnia, wishbone fl ower, caladium, balsam, gerbera daisy, gaillardia, celosia, lantana, scaevola, melampodium, butterfly weed, shrimp plant, cleome, four o’clock, perilla, hardy hibiscus (mallow), sunflower, salvias and cigar flower.
- Plant sunflowers in late summer for fall flower arrangements. Flower colors include yellow, orange, red, bronze, white and combinations of these. It usually requires about 60-80 days from sowing seed until first flower color.
- Prune azaleas no later than mid-July. Pruning azaleas after early to midsummer may remove next season’s developing flower buds. This applies to most spring-flowering shrubs as well as hydrangeas and gardenias.
- In early summer, gardenias may have aphids, whiteflies and the associated black sooty mold. For optimum plant performance, control the insects with Orthene or a light horticultural oil spray.
- Keep caladiums well-watered during hot, dry weather to keep the foliage in good shape through the summer. You may apply a fertilizer now to encourage vigorous growth. Break off any flowers that form.
- Prune repeat-flowering roses in late August or early September. This stimulates vigorous growth for the fall blooming season. Cut the bushes back about one-third their height, and remove any dead growth. Fertilize with a general-purpose fertilizer or rose fertilizer following package directions after pruning.
- Louisiana irises are semi-dormant in late summer. Prune off seedpods and yellow or brown foliage to help keep the plants more attractive. You may transplant or divide Louisiana irises beginning in August.
- Cut faded flowers from flowering annuals and perennials to encourage new growth and flowers. Ol blooms and seed heads left on the plants can retard continued flower production.
- Finish any pruning you may need to do to shrubs in the landscape, particularly those that bloom in winter or spring. Pruning later (after June) may interfere with flowering.
- Keep up with weeding. This time of year, weeds can get out of hand very fast. Use mulches wherever possible. If you need help with herbicide recommendations, contact GroundHOG. Avoid applying most lawn weed killers during summer because high temperatures increase the chance that they will damage your lawn grass.
Source: LSU AgCenter