As June melts into July, I try to get into my garden early and back inside before the heat builds to an intolerable level. I may return to pick blueberries at dusk. As the daily heat index soars, it’s important to listen to my body and head indoors to cool off before I get dizzy from heat stress. Extreme heat is dangerous. For gardeners in our area, extreme heat is a summer fact.
Daily predictions for the heat index are routine. Simply put, the heat index is a “feels like” temperature. The heat index assumes body mass, physical activity and individual heat tolerance. Each of us does experience heat differently. Those who regularly work outdoors often tolerate more heat than those spending days in air conditioned comfort. But, by considering the relative humidity along with the actual temperature, the heat index can alert anyone working outdoors to take extra care. For example, if the temperature in the shade with a light breeze blowing is 90 degrees with 70% relative humidity, the heat index will be 106 degrees. Exposure to full sunshine can increase heat index values by up to 15 degrees. At a heat index of 106 degrees, heat exhaustion is a real possibility.
We know the drill. When heat rises, drink plenty of cool (not cold) water, wear loose light clothing and a hat, and take frequent breaks. Pay attention. If you cannot think clearly, before you get dizzy, or experience muscle cramps, or develop a headache, get out of the heat. No one wants heat exhaustion. No one should push oneself past a comfortable level to a point where heat stroke may become an emergency situation.
Several of my Master Gardener friends routinely set smart phones to remind them to take breaks when working outdoors. It’s easy to lose track of time or to push oneself to complete a task, so a reminder to stop, drink water, and rest can be helpful. The National Institute for Occupational Safety & Health offers a free, convenient app that provides real-time heat index information, with customizable alerts to take breaks. Download this free app.
Fortunately, most home gardeners can stop working outside when heat rises to dangerous levels. Those whose jobs require them to be outside must be extra careful in the heat. Use the heat index as a screening tool. Supervisors should recognize when preventive options must be implemented. As heat increases, more water and rest breaks become necessary. If conditions are extreme, then reschedule non-essential work. Every year, almost 70,000 visit an emergency room because of heat stress, and over 700 people die because of heat stroke. Our public safety and EMT workers have to work in this heat; let’s not ask them to risk their lives to save ours.
Plants are also susceptible to extreme heat. Obviously, plants need more water. Check containers at least once a day, or more during really hot weather. If you find yourself watering a plant that doesn’t seem to retain moisture, you may have to break up a dry crust of peat moss and loosen the soil at the top of the container so that water can be absorbed. You can also set a container into a bucket for awhile so that water can be taken up through the drainage holes; just be sure not to overwater. Re-pot if the container has become root bound. Add damp potting mix to the bottom of the container to help keep the soil moist.
Fertilize summer container plants. A water-soluble or liquid complete fertilizer help as plants take up more nutrients in the growing season. However, as temperatures climb above 85 degrees, plants will slow or even stop metabolic processes. If applying systemic herbicides to control weeds, apply them early in the day. Chamberbitter is notoriously prevalent now. See the Clemson Home and Garden Information Center factsheets to identify and choose the correct formulations to control the specific types of weeds in your lawn and flower beds. To reduce the chances of the herbicide vaporizing and moving with the breeze onto unintended targets, avoid applications when temperatures are over 90 degrees or during periods of little to no rainfall.
Take care of pets and wild birds in this heat as well. My dogs let me know that they are not interested in a mid-day run for now. Typically, they are happy to run early and late, but with hotter temperatures at midday, they are content with a quick walk and an immediate retreat to the comfort of our screened porch under a fan, or better yet, the cool recess of a living room. I change their water every day, and sometimes twice a day. I also replace my hummingbirds’ sugar water more often.
With extra attention and consideration, the extreme heat and humidity typical of July and August in the CSRA will eventually pass us by. We can look forward to cooler temps by late September. For now, if working or playing out in the summer heat, take care and stay cool.
The Aiken Master Gardeners will be at the Farmers Market early Saturday mornings, in the shade, to assist you with all of your home gardening questions.