Hi, 

We would generally not advise to prune in high heat in the middle of the summer beyond any broken or dying branches. 

It also depends on the plants and if it is the right time of year due to blooming etc. Most plants don't need to be pruned beyond perhaps some general shaping; if you are pruning to maintain a certain size, this can stress the plants and overtime cause health issues. 

As a general rule of thumb though it would not be great to prune in high heat and if they need to, then early morning when it isn't so hot would be best. 

Here are some links to our pruning resource pages to help with additional guidance. 

https://extension.umd.edu/resource/pruning-tree-and-shrub-basics/

https://extension.umd.edu/resource/pruning-shrubs-and-hedges-home-garden/

https://extension.umd.edu/resource/pruning-trees-home-landscape/

https://extension.umd.edu/resource/pruning-tools/

Let us know if  you have further questions.

Emily

Thank you! Very grateful.

you're welcome!