Are you Giving Up on Your Plants Due to the Heat?: Let’s Talk Plant Survival
By Connie Whitlock
Publishing Editor
If you walk by the average flowerbed in Pleasant Hill you might have noticed some aren’t looking as vibrant as they did when the planting season began.
The plants are drooping, leaves turning brown around the edges, and hanging baskets need water every time you turn around. Have you seen the tomato plants? I think they have given up altogether.
Welcome to late summer heat wave in Missouri. The prolonged heat and dry conditions are putting plants under some serious stress. University of Missouri Extension reported this week that high temperatures combined with declining soil moisture are taking a toll across the state.
But before you drag out the hose and start drowning everything in sight, there are a few things to know.
Wilting Doesn’t Always Mean “Give Me Water”
I can see your eyebrow move up with a look of skepticism. When we see a wilted plant, the natural reaction is to grab the hose. But a drooping plant doesn’t necessarily mean the soil is dry. Plants lose water through their leaves in a process called transpiration. That evaporation actually helps cool the plant. During extremely hot weather, however, a plant can lose water faster than its roots can replace it. The result is a plant that looks pretty miserable in the afternoon.
It may perk back up when temperatures fall in the evening. So before adding more water, stick your finger into the soil or grab a small trowel and check it. University of Missouri Extension recommends checking the soil several inches below the surface. The goal is moist soil, not soggy soil. Too much water can deprive roots of oxygen and cause another set of problems for an already stressed plant.
In other words, don’t diagnose your plant from the leaves alone. Check the dirt.
Deep Drinks Are Better Than Little Sips
If your garden really is dry, give it a good drink. Frequent, shallow watering encourages roots to remain near the surface, where the soil heats and dries quickly. A slower, deeper watering gets moisture farther into the root zone.
If you really want to give your plants what they need, use a good soaker hose and drip irrigation. These are very useful because they put the water near the soil rather than water evaporating in the air. According to the MU Extension checking after watering to see whether moisture has reached roughly the top six inches of the soil is prudent.
If you have planted trees recently, they will need basically the same care. A quick spray around the trunk isn’t the same as slowly soaking the root area.
Morning Is Your Friend
MU Extension says the best time to water your garden is between 6 and 8 A.M. Temps are cooler and there is less water evaporation around this time. Evening can be good too although repeatedly leaving foliage wet overnight can cause plant disease. Try to avoid watering mid day when it is the hottest. Your water will evaporate fast. The worst time to water is generally right in the middle of a blazing afternoon, when evaporation is highest. And while you’re at it, save yourself from the heat too.
Pay Extra Attention to Pots and Hanging Baskets
You might love those hanging plants and even though in May you will be watering them every other day, during the heat wave, your watering habits will have to shift. Containers have a limited amount of soil to hold moisture, and wind increases the amount of water plants lose. Outdoor potted plants will need more water than indoor plants.
Also, check where your pot is sitting. A container baking on the concrete in the full afternoon sun is absorbing heat from below and above. You might consider moving it to a shady grassy area in the afternoon to give it a break.
And Then There Are the Tomatoes
You might notice your tomato plants are not producing as much fruit and this can be due to the high heat. According to the MU Extension sate horticulturist, David Trinklein, fruit set can suffer when daytime temperatures rise above 0- degrees and nighttime temperatures remain above 70. High temperatures can interfere with pollen development and fertilization, meaning blossoms may appear but fail to become tomatoes. It also interferes with ripening.
Don’t Panic Over Every Brown Leaf
You might notice brown edges scorched leaves, and if you are like me, you have some yellow leaves and even see more leaves dropping on the ground or table. Plants have survival mechanisms too, and dropping foliage can reduce the amount of water a stressed plant must support.
This isn’t necessarily the best time to start aggressively cutting, fertilizing and otherwise trying to force a struggling plant back into looking like it did in June. Keep it adequately watered, watch it and give it some time.
Once temperatures moderate, you’ll have a much better idea of what was temporarily stressed and what suffered permanent damage.
A Little Mulch Can Go a Long Way
If you’ve got bare soil around your plants, mulch can help. A layer of organic mulch helps reduce evaporation from the soil and moderates soil temperatures. Just don’t pile mulch directly against plant stems or tree trunks.
Your Yard May Not Look Perfect Right Now and That’s OK
Perhaps the most important thing to remember is that a Missouri garden in September isn’t supposed to look exactly like it did in May. Plants have been through months of sun, storms, insects, humidity and now prolonged heat. Some will look rough, some flowers will stop blooming, some leaves will scorch, and some tomatoes will take a break, and unfortunately, a few plants may not make it.
The answer isn’t necessarily more water, more fertilizer or more work. Sometimes the best thing we can do is keep the soil adequately moist, protect vulnerable plants where we can and wait for Mother Nature to turn down the thermostat.
If you are tired of this heat, chances are your plants are too.