You are correct in surmising that the Department of Agriculture’s plant zones are utterly no help for Western gardeners because we have too many plant zones here. For example, according to the editors of Sunset, San Diego County has 11 different planting zones, but the US Dept. of Agriculture’s map showing the planting zones for the west puts Phoenix Arizona in the same zone as coastal California. This is obviously asinine. Due to this problem, Lane Publishing, the original publishers of Sunset magazine and books created far better plant zones for the west. Campo California shares the climate of California’s Gray Pine Belt and Oregon’s Rogue River Valley, and Southern California’s Mountains. You have sharply defined but mild winters and hot summers. You can grow flower bulbs, peonies, eastern lilacs, flowering cherries, and deciduous fruit trees, including pears, apples, peaches, and cherries. Grow these things and if you want a lawn try one of the new varieties of buffalo grass developed by the Dept. of Agriculture. It goes dormant in winter but is very drought resistant and easy to grow. By choosing these plants, you can have a lovely and productive garden.

One is the exposure. If it is very hot in summer where you live, plant your hydrangea in partial shade, preferably against a wall on the east side of your home where the plant will get full sun all morning and full shade all afternoon. Morning sun is great since it is cooler and just when your plant has had enough it will be able to cool off in the shade. If on the contrary, you plant your hydrangea facing west, where it will get full shade all morning and full sun all afternoon then it will be comfortable all morning and fry in burning hot sun every afternoon. This is a recipe for disaster and the plant will burn and usually get sick and die, perhaps from spider mites that always attack plants put in the wrong places. In Sunset Zone 24, right along the coast, exposure does not matter, but where you live it does matter and hydrangeas definitely need to face east or they will die or do badly.

Secondly is the matter of soil. Hydrangeas like loose, well-drained soil with plenty of organic matter worked in. If your garden is solid clay with poor drainage, amend the soil and be sure to dig a coffee can full of gypsum into the bottom of the planting hole to improve drainage. If last time you failed to do this, chances are that your hydrangea died from root rot.

The third important necessity is water. Hydrangeas are not drought-resistant. They need constantly moist soil. So make sure that you provide adequate irrigation. If you only water once a week with the hose, put a watering can next to the plant, fill it with water every time you irrigate and then pour it over the roots half way between waterings. If weather is very hot you may need two or even more watering cans.

The last requirement is plenty of room for its roots. Hydrangeas will grow in the ground or in large tubs. If you try to grow a hydrangea in a small 8 or 10 inch pot, it will die.

And finally: Be sure to fertilize your plant. Our native California soils contain little nitrogen so it’s up to you to provide it. Feed your hydrangea throughout the growing season with a balance fertilizer containing bloom and growth ingredients. The variety you wish to grow, ‘Incredibals’ by Proven Winners, has extra large white flowers and these do not turn blue. Thus any good-quality, balanced, organic fertilizer can be used to feed it. But if you were growing a blue hydrangea you should be fertilizing it with Aluminum sulfate. Aluminum sulfate will turn hydrangea flowers blue if they are the type that will turn blue, or it will keep hydrangea flowers blue if you begin fertilizing in October with a solution of it, mixed according to package directions and keep it up every two weeks until bloom. Red hydrangeas and most white varieties also will never turn blue but most pink varieties will turn blue if grown in acid soil.