It seems much too early in the season to be talking about heat waves, but here we are! Last week, Massachusetts saw its first heat wave of 2021. A heat wave is defined as three or more consecutive days of 90 degrees or higher. This coupled with below average rainfall is creating uncomfortably hot temperatures for many of our early crops. 

The first crops to go into the ground are typically things that prefer cooler temperatures such as lettuce, spinach, peas, broccoli, escarole and bok choy. If the temperatures get too high, there is a chance they may begin to bolt, which means they flower and then go to seed. This is the plant’s way of saying, “Oh it’s too hot to continue growing so it’s time to produce an heir to come back when the conditions are better”. This season, we lost our first seeding of bok choy and our broccoli was ready to harvest two weeks too early! But don’t worry, the bok choy is making its way to a local family that keeps about 40 birds and the broccoli was donated to St. Bridget’s Food Pantry. 

For the rest of the crops that need help staying cool, we’ve been constantly irrigating to try to reduce the soil and air temperature right around the crops. Wet soil absorbs heat more slowly than dry soil and therefore can help to reduce the soil temperature and the air just at the surface. Sprinklers are also helpful as the water in the air stimulates evaporation, which slightly reduces the air temperature.

Another trick we have when we absolutely need to, is to temporarily stop weeding. Seems a little counterproductive, right? However, on very hot days, with no rain in sight, it’s important to keep as much moisture in the soil as possible. When we weed, we disturb the soil surface and expose the lower, cooler, wetter layers of the beds. This will increase evaporation of what little moisture there is and risk stressing the crops out more if we are unable to irrigate right away. In some situations, it can actually help to keep the weeds and leave the soil undisturbed. And in some extreme cases, if the weeds are taller than the crop, it can even provide some shade! 

So there you have it, a few techniques we use to battle the heat. I certainly hope we have a break from such high temperatures for a little while, but I’m not holding my breath! As we move forward into the season, we will continue to take care of our crops as well as ourselves on these extremely hot days.

Until next time,