How the summer heat causes stress in plants
Last week brought some of the warmest temperatures we’ve seen in almost four years in Mid-Missouri. Temperatures climbed above 100 degrees, with heat indices approaching 115 in many spots. It’s these temperatures that caused some plants to show signs of heat stress. However, the “cooler” weather that returned to Mid-Missouri allowed plants to take a breather.
Giving Gardens greenhouse manager Tammy Cundiff says that those cool days are good for plants. Even plants that are heat tolerant were in great need of cooler weather.
According to Cundiff, plants can usually tolerate the heat if they are native to an area. For Missouri that would include:
– Cardinal flower
– Black-eyed Susan
– A variety of coneflowers
– Southern Blue Flag
– Palm Sedge
– Spice Bush
– Columbine
– Prairie Blazing Star
– Little Bluestem
Those are just the most common flowering plants native to Missouri. Even those plants can take a beating from the heat and the most common mistake during the hot months is when to water.
“When something is really, really dry you shouldn’t be giving it fertilizer at that point in time, you should water it first and then go back and give it some fertilizer,” Cundiff says. “But when it’s really, really dry, it’s best just to go with plain water.”
Cundiff says the best time to water is in the early morning before the heat of the day sets in, but even some heat-tolerant plants can fall ill.
“In my yard in particular we have lots of coneflowers, which are very very heat tolerant, but even right now they are stressing some,” Cundiff says. “I won’t lose any of them, but I know when I have to water those, we are having a really hot and dry summer.”
Some signs you need to watch for when it comes to heat stress include:
– Wilting of the leaves. Even the most heat-tolerant plants can wilt in the hot summer months
– Bleached leaves, which indicates a sunburn of the leaf
– Yellowing of the interior leaves
– Dropping of the leaves
– Crunchy leaves
Unlike last week, the heat building into Mid-Missouri will be brief. For more on that stay tuned to ABC 17 Stormtrack Weather and follow us on Twitter @ABC17Stormtrack.
