Hot Plants -- How Midwest Plants Can Survive Extreme Heat

How much heat can a plant take?
She said yes!  Then, the robust hydrangea planted in the yard in anticipation of the firstborn's wedding  suddenly collapsed, brilliant blooms curling inward. 

For the past week temperatures have topped ninety degrees by mid-afternoon.  How can tender and newly planted flowers and shrubs survive this persistent heat?

Water is essential, but not the only defense.  Early morning watering helps, but if a plant is located in hot afternoon sun, it may still wilt.  If wind accompanies the heat, supplement water intake with hydration.  Direct a sold stream of H2O to the root and drip line of the plant.  Water on the leaves could act as a magnifier in the hot sun--so minimize overspray.

Some sagging isn't hazardous to the long-term health of a plant, particularly if it's well established.  Plants, like people,
tend to droop in high heat, but normally the luster's restored as soon as temperatures are back in the seventies to mid-eighties. 

Heat scorched leaves may be unavoidable and should be snipped away.  They won't hurt the plant, clipping only improves aesthetics and promotes regrowth.

Nevertheless, more than a couple days of significant wilt ,( i.e. reduction of the plant to less than a third of  normal height) can be deadly. 

If that's the case, the solution isn't terribly pretty--but it works.  Throw shade!  Fashion an open sided heat shield.  Nothing fancy, prop up some cardboard or a sheet.  Don't lay the material directly on the plant.  Leave room for air to circulate,  or a "hothouse" effect will follow. 

Once the heat wave passes, trim any permanent damage and increase water for a few weeks.

Don't fertilize until the plant is back in fighting shape.


By the time fall nuptials occur, the hydrangea should be big and blooming. 

But all eyes will be on the bride ...

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