How to Protect your Plants from Extreme Summer Heat

To say that this Summer has been hot is an understatement.  June 2021 was America’s hottest June in 127 years of records. Remember the deadly late-June heatwave that hit the northwestern US and western Canada?

Obviously, humans are thankful they can get out of the heat and cool down in air-conditioned buildings.  But what about our garden plants? We can’t just dig them up and bring them inside when temperatures soar.

Thankfully there are several ways to reduce heat stress in plants.


Don’t transplant or plant

Seedlings won’t survive in soil that’s too warm. Postpone any transplanting until the cooler temperatures of fall have arrived.


Don’t prune your shrubs and trees

In really hot weather, the leaves that will become exposed from what you’ve pruned away will actually sunburn. This also can leave them vulnerable to damaging insects.


Hold off on the fertilizing

It’s not ideal to encourage new growth during a heatwave.


Steer clear of chemicals

Some plant types, like conifers and succulents, can be hurt further when you apply any kind of chemical treatment, including soap or neem oil, during extremely hot weather.




Weed out the weeds

Weeds are generally hardier than your garden plants and will compete for water and nutrients.



Adding mulch will make much-needed moisture stick around longer by delaying evaporation. This is especially true in young plants.


Deep Watering

For mature plants, deep watering is generally better than shallow watering. Also, watering during cooler morning temperatures is helpful to heat-stressed plants.  This applies to plants and trees alike.


Water young plants more often

As their roots have not yet become well-developed, young plants are especially vulnerable to heat stress and will benefit from more frequent watering.


Get in the shade

Place your container plants in shaded areas, or provide shade cloth to protect them. Note that some periods of direct sunlight are beneficial. But hours and hours of exposure to intense sun can be harmful. Consider placing container plants in shade during the heat of the day, and move them into the sun towards the end of the day.


Allow them some humidity

In a garden setting, too much humidity on leaves can encourage mold and increase susceptibility to disease. But a light misting overhead during the morning can help garden plants overcome heat stress.


Having extremes in air and soil temperature will slow down the natural chemical activity and growth in plants. Ideally, plants grow best when the range of temperature falls between 59 to 86 degrees Fahrenheit.

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