How to keep garden cool in hot temperatures
Create natural shade areas. Plant suitable tree/ large shrub so the dappled shade brings temperatures down. Combining different heights of plants and creating layers of shade is most effective for reducing temperatures.
Cover house walls with suitable vines, ornamental or edible, to cool the areas by as much as 7 degrees and providing cooling places for insects.
Reduce any hard no permeable surfaces like macadam and substitute with permeable materials like wood or mix paving with grass or other low planting.
Increase rate of evaporation of the site by introducing water feature or using drought tolerant plants like rosemary, lavender, Echinacea or Yarrow.
Apply additional layer of mulch of compost around the roots of plants in the autumn to improve water absorption.