Gardening in Extreme Heat

The extreme heat takes a toll on living beings, like animals and people. But plants too need additional help to endure the heatwave.  

In the near 100 degree weather, a garden should be watered early in the day or late at night in order to increase water retention in the soil and not to burn water-splatted greenery. In extreme heat, watering on both ends of the day may be necessary. That is especially true for annuals since they don’t develop deep branched root systems, and herbaceous plants because there is no protective layer on the stems.  

While a drip system delivers water with minimal loss to evaporation, watering with a hose or cane can accomplish the same when done carefully — that is watering the soil close to the plant. Plants do best when the moisture seeps to at least 6 inches deep while watering. Remember that plants in sandy soil don’t get the same water retention as plants in clay soils do. 

In general, plants in pots require more frequent watering than those in the ground, while hanging baskets are more exposed to the heat than pots on the ground. Seedlings are more fragile than mature plants and therefore need extra attention to keep the soil moist. Inserting a finger in the soil next to the plant base about two inches below the surface, will be a good way to check for soil moisture at the root level.  

Mulching with grass clippings or compost helps water retention as well. Acid–loving plants can be mulched with saw dust or pine needles to help lower pH with each watering. Weeding removes other plants competing for moisture. 

Labels of purchased plants or online information will generally tell the gardener about required growing conditions. But a wilting plant is a cry for help — shade may be needed. Shade cloths are available in garden stores, but they require some form of frame, designed or improvised. And such protection needs to be placed at least a foot above the plant to allow for air circulation. Ultimately, the shade cloth should lower the air temperature by about 10 degrees. Potted plants can be moved to a shady spot. 

In extreme heat, which causes stress, transplanting, pruning, or fertilizing should be avoided. Those activities cause plants to re-orient their metabolism and add to the stress.   

As for the gardener? Don’t garden outside in the hottest part of the day, wear a large brim hat, apply sunscreen, and drink enough water to keep you hydrated as well. Don’t chance a heat stroke — your garden needs you. 

By Joanna Rosińska