Hydrangea Love

Protecting your plants from intense summer heat in Portland Oregon

Here are several lessons in this story for you, O gentle reader………..how to successfully transplant a shrub or tree in July heat, how to prevent leaf and flower scorch damage to your plants when we have intense hot weather right on top of weeks of cool rain, (more critical if you agreed to have your garden on a fundraiser tour).  This will also work to restore plants in a container that you forgot to water??? These helpful lessons all fit into this story.

Mary and Oliver Beloved Hydrangeas

The story:  My mom and dad planted and named two hydrangea by the back patio, Mary and Oliver.  Mary was beautiful all summer long no matter what but Oliver had troubles.  Every year in early summer, Oliver’s flowers would get crisped.  Completely crisped. If they had planted Oliver a few feet closer to the covered patio there would be no problem and no story.   They planted Mary in the afternoon shade of the patio but Oliver got the early afternoon sun in June and July. He was just not a super sun tolerant kind of guy and most hydrangeas would have some difficulty in this situation.

He could handle the sun a little better once the leaves and petals had hardened off in July but in early June, while the leaves and petals were full of spring’s moisture and freshly unfurled, a 100 degree day or two would toast all the flower heads on the plant.  So Oliver’s flowers would scorch and my parents would then over water Oliver trying to get some water back into his petals. They did not understand that once petals are scorched they stay that way. Oliver would open up new flowers in July and they were fine initially but now the plant’s leaves looked terrible because? Over watering caused the roots to rot, the leaves to wilt and yellow. Oliver was a mess.  I offered to come over and protect Oliver from them. The humans, Mary and Oliver, old family friends (around before I was even born) had long since gone on.  These plants were symbols of their dear friends.

The Sheet Trick Protects Plants from Intense Heat in Portland Oregon

So how did I do this?  The Sheet Trick!  My first solution was to be sure the plants were watered deeply once or twice a week only.  No more overwatering. The second solution was to protect Oliver from intense sun.  If I was expecting intense sun,  I would drive over, get out some binder clips, drape a white sheet over Oliver to cover all his leaves and flowers and then clip the sheet onto various large stems so it could not come off.

Because the leaves were covered (this is science folks!) the cells int the leaves closed and held in the water rather than letting it go into the air.  This process is called transpiration. Transpiration is part of the plants photosynthesis process with the sun.  See Wikipedia on photosynthesis.  Since the flower petals and leaves kept their water, they stayed cool enough and did not scorch. I would not leave the sheet on for more three days at a time so I didn’t have to go over there every single day, just when I knew it was going to be hot.  Leave it on too long and you will starve your plant.  Plants eat sunlight.  3 days is the maximum.

Best Garden Tip Ever for Portland Oregon

What’s important for you gentle reader is that this sheet trick is handy beyond belief for all kinds of things.  Number 1  best tip ever for transplanting a shrub in the summer…….keep it covered for 3 days and I mean immediately after it is in its new place or cover it even during the digging of the plant if you are feeling compulsive.  Use it to protect flowering plants if we have intense heat while the flower petals are still new and soft. Use this trick if you have had an irrigation boo boo and your plants in one area didn’t get any water and  have wilted.  Presto, sprinkle the leaves with water gently, water the plants soil and cover for a few days……..your plant will have a better chance of recovery.  Its not just the flowers, as I have used the sheet trick to protect clients japanese maple leaves very successfully too.

Every generation loves hydrangeas, my parents loved theirs, I love them although confess I have none of my own down here on the floating river house,  They also look mighty fine with ornamental grasses so not just for an old fashioned garden but could be used in more modern gardens if placed thoughtfully. They are creating new hydrangea varieties whose leaves can handle more sun.  There are few varieties out there now (in 2026) and I promise to write a blog about them soon.

Gentle reader, please go forth better informed and be even more successful with your plants this summer.

Carol 

Landscape Designer (Landscape Design in a Day)