How to Care for Your Garden in Extreme Heat

Most garden plants in our region start to struggle when temperatures rise above the mid-80’s. Here at Wellfield, we use the following measures to keep our gardens looking healthy in extreme temps:

Water the turf and don’t drive on it (a mistake I am guilty of making!). Consistent water on our turf before it turns brown helps keep the ground moist for the shallow roots of turf grass. Thankfully, many areas of our grass are in the shade! This is one of the main reasons manicured turf lawns are losing their luster in favor of planted beds, extended vegetable gardens, or native landscapes. 

Wellfield is lucky to have an abundant source of groundwater to use in our automated irrigation systems. The irrigation is programmed to turn on each morning in a different section of the garden; you may notice the tall sprinklers running in the Island Garden throughout the summer. These are some of the many manual watering systems we have in place to supplement areas out of reach of the current irrigation system, or areas that just have a lot more sun and need some help! We make sure to water early in the morning to avoid losing water to evaporation and to allow time for the leaves to dry off during excessive humidity. 

We try to avoid fertilizing in extreme temperatures, as well. The plants take a little break from actively growing under these conditions, so added fertilizer will just build up and cause burn injuries to the plant (as well as salt buildup in the soil). Extreme heat can also be detrimental to herbicide uptake, for the same reason. 

Mulch (specifically wood chip mulch) helps keep moisture in the ground, and the sun off of shallow roots. This is another reason groundcovers are advocated in landscape design. Bare, open soil with large spacing in between plants will require more water, more frequently. 

Wellfield has a shade frame for some of our plants-in-waiting. Shade covers are popular for vegetable plants, especially. At home, we can use old white sheets, old window screens, or even cut down old shade cloths thrown out from a commercial greenhouse to protect some of our more tender species. Make sure to check on cooler spring crops, such as brassicas, lettuces, and root crops to either harvest or cut out any bolting that is bound to occur. Blossom end rot of tomatoes and peppers is prone to occur in extreme heat, as well. Combat this by adding calcium to the soil and keep it evenly moist. 

And you know this next point is going to come up! Using native plants adapted to the environment is a great way to conserve water and lower maintenance requirements. We almost never have to supplementally water the Children’s Garden Prairie (at the entrance to the Children’s Garden). Aside from natives, it’s important to choose the right plant for the right place. If we have a sunny, dry side of a wall or building, we plan appropriately for drought tolerant species. The opposite is true also for our shoreline and shade areas. If we discover a plant isn’t happy where it’s located, we try to rehabilitate it in a more tolerable area and choose a better match for the vacated spot. 

Sometimes the best thing we can all do in extreme weather is to wait it out, and resume our work when conditions are more tolerable. The plants (and weeds) will also be waiting it out with us! 

Mary Wojcik, Lead Horticulturist

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