While it is generally not so pleasant to be outside in summer in Florida, yard chores still need to be done. It is helpful to be an early riser, so that you can avoid the worst heat of the day before taking refuge inside your house.
But what about your plants and trees? They have no option of uprooting themselves and following you into the house. And, you can't grow your whole landscape in pots and then haul it all inside for the summer.
So what are the options? You can keep the plants adequately watered, mulched, fed, and planted in the correct amount of sun or shade. But all of this may not work if the plants are not capable of withstanding our high temperatures for so many days every year.
Instead, you need to grow plants that have the ability to stand the heat. Usually, the plants which cannot tolerate our conditions are not found in nurseries. But the plant label may or may not include heat tolerance, sometimes leaving you to do our own research.
The USDA Plant Hardiness Zone chart tells us how much cold weather that it will take to kill or damage our plants. But it says nothing about how much heat the plants can stand. Fortunately, we do have a little-known chart available. It is called the American Horticultural Society Heat-Zone Map.
Since Osceola County is in zone 9 for cold tolerance, does that mean that it is also in zone 9 for heat? Unfortunately, it does not. The entire county is in heat zone 10, getting 150-180 days annually of temperatures over 86 degrees. Many plants consider this temperature to be too hot, causing extra stress.
What if the label just says zone 9? Being in zone 9b, we would consider the plant to be appropriate since it should not freeze. However, our summer weather does not meet the standards for zone 9. Our heat zone rating is zone 10. If the label says zones 9-10, we should be able to safely buy that plant.
What symptoms does a heat stressed plant have? Of course leaves can wilt, but things can get worse than that. Flower buds can wither and die, leaf color can fade, roots can stop growing, and the plant may become more vulnerable to pests. Heat-stressed plants do not die quickly, but enter a slow decline, as the high temperatures have a cumulative effect.
Prevention of heat-related death in plants begins with choosing the right plants. Starting with bedding plants, here are a few examples of heat tolerant ones: vinca (periwinkle), coleus, caladium, torenia, and zinnia.
Perennials include scarlet salvia, pentas, shrimp plant, and lantana. If you like herbs, try rosemary, Mexican tarragon, ginger, cumin, and summer savory.
For veggies, you can go for okra, Southern peas, Sweet potato, and various hot peppers. We also have some tropical veggies such as calabaza, chayote, and Seminole pumpkin. For tomatoes, the best bet would be the cherry tomato, as most full size ones will not set fruit with day temperatures over 85 degrees and night temperatures over 70 degrees.
In the veggie garden, we also have another option. Why not take a break and solarize the soil instead? Soil Solarization is a process in which clear plastic is laid over the earth to create enough heat to kill nematodes, weeds, and pathogens. This process will enable you to do better in the fall when you feel like planting again. Just anchor down your plastic and leave it for six weeks.
What about palms and trees? Most palms can take heat, so just check for cold hardiness instead. As for trees, some can take heat, and some won't like it. You can try loquat, crape myrtle, yellow tabebuia, pink tabebuia, red maple, live oak, sand live oak, bald cypress and pond cypress.
For a more complete guide to plant selection, check the Florida-Friendly Landscaping Guide to Plant Selection & Landscape Design. Find it at this link: https://ffl.ifas.ufl.edu/media/fflifasufledu/docs/FFL-Plant-Guide_v03222022_web.pdf
Need to talk to someone about your landscape? Reach the UF/IFAS Extension Osceola County at 321-697-3000.
