LSU AgCenter Horticulturist
(06/21/19) Excuse me, did someone put the heater on? It’s getting hot out there, and summer officially began on June 21, the summer solstice. We are fortunate in many ways to live in a state that allows a year-round growing season for flower and vegetable gardens, and south Louisiana is considered to have a subtropical climate.
Louisiana gets on average 108 days of rainfall, dumping 63 inches of rain annually with 2,644 hours of sunlight. This makes the long, HOT and humid summers combined with mild winters conducive to biological growth of all kinds — including many tropical plants and some not-so-favorable things such as fungal and bacterial growth that may attack plants.
So, how do we get our plants through this hot summer, especially in extended periods of drought followed by downpours? Mainly by making sure that plants do not become stressed. As weather heats up, many plants, especially smaller, newly placed plants, will become stressed by the heat. And don’t forget about those container plants. They will become even more reliant on the gardener for help as heat builds up.
To combat the heat, plants have many defenses; however, they mainly combat the heat just as we do: with water. Well, kind of. Plants use evapotranspiration to cool themselves by transferring water to their surface, kind of like sweating for us in that it serves the purpose of removing heat and cooling.
We can do several things to help our plants this summer. But we must first take care of ourselves. Remember to work in the cooler mornings and evenings during summer, wear large-brimmed hats when out in the sun, apply sunscreen to protect your skin from damaging UV rays, and drink plenty of fluids and replenish electrolytes when working in the summer heat. Take breaks in the shade or go indoors frequently.
Here are a few tips to help your plants survive the summer heat.
- Ensure plants are established before the summer really heats up. We still have three more months of solid heat in Louisiana, with July and August being worst. Now is not the best time to plant; however, container plants can still be installed, but be sure to water heavily for the first couple of weeks to get good establishment.
- Mulch your plants. Pine straw, pink bark mulch or other materials should be applied to the soil at a 2-inch depth to keep the air from evaporating the water from the soil as quickly.
- Water in the mornings or late evenings. Mornings are the best to help prevent heat stress to plants, especially on hot days. It is also a great way to conserve water. We all know how much water bills go up in the summertime. Light watering every other morning will help when heavy, deep rains have been scarce.
- Use drip irrigation. Drip irrigation will both save you time and conserve water while reducing water costs. When you use drip irrigation at the surface of the soil, the water seeps slowly down to the roots of the plant and evaporates less rapidly than if watering by hand or by irrigation sprayers where the water droplets are exposed to the air. This will also cool the roots and prevent plant stress. Disease and pests love nothing more than an easy target. By keeping plants less stressed, you provide vigor against disease and insects. Additionally, overhead watering encourages both bacterial and fungal growth at the site of the water droplets on the leaves and stems. So, all in all, drip or soaker hoses are the way to go. Additionally, many types of automatic timers can be set to water on certain days for a given period at specific times, making this a cinch.
- Provide shade. Plants appreciate some good shade in the summer just as much as we do. Direct sunlight can be damaging to plants and even cause burning, especially new or unhealthy plants. You can use sun screen fabric that reduces temperatures as much as 15 degrees while also blocking UV rays. The fabric is breathable and allows air movement. These can be found at local garden and retail chain stores. You can also use light-colored landscape fabric.
- Control the competition. Control the weeds that compete for water. The best defense is often a good offense. Healthy lawns and gardens that do not have weeds will be thicker and more vigorous, making it harder for weeds to grow and compete for both water and nutrients that plants need to survive.
- Be on top of your game. The best gardens are those visited often. Just a walk around your garden helps you spot heat stress, disease stress and pest damage. Use a benchmark plant or sentinel plant to gauge the water needs and overall stress level of the garden. Large-leafed plants like zucchini will show signs of wilting long before some other small-leafed plants. This will help show you when watering is necessary.
- Don’t forget about vacation. No, I don’t mean go take a vacation to help your plants, although it will help you greatly. We all remember to set the alarm, make sure the dogs have a sitter, turn off the AC, take out the trash, start the dishwasher, lock all the doors and windows and ask a neighbor to pick up the mail and keep an eye on the house. But many people forget about their plants. It’s No. 2 on my vacation checkoff list after the dogs.
We gardeners put a lot of sweat and hard work into our lawns and gardens. We don’t want them dying while on vacation. Our lawns are an extension of our homes, and we put a great deal of money and hard work into them. If you don’t have irrigation set on timers, ask the neighbors to water once or twice if there is no rain. There will be enough grass to cut when you get back not to have to worry about pulling out dead plants or trying to raise plants from the dead this summer.
Container plants should be watered heavily for the first couple of weeks to get good establishment. Photo by Heather Kirk-Ballard/LSU AgCenter
Pine straw, pink bark mulch or other materials should be applied to the soil at a 2-inch depth to keep the air from evaporating the water from the soil as quickly. Photo by Heather Kirk-Ballard/LSU AgCenter
Watering in the morning or late evening help prevent heat stress to plants, especially on hot days. Photo by Heather Kirk-Ballard/LSU AgCenter