When to Prune Hydrangeas in Arizona
Hydrangea pruning in Arizona doesn’t follow the calendar most gardening advice assumes.
Home & garden, state by state
Everything we have worked out for Arizona: what to plant and when, which varieties finish in time, the pests that actually turn up here, and the jobs that pay off month by month. We also cover the rest of the property, from lawns and soil to home care and energy, because a garden rarely stops at the vegetable bed.
The numbers first, because everything else follows from them. Measured at the weather station in Phoenix, the last spring freeze falls around no freeze in most years; a rare cold snap can bring 32F between late December and mid January and the first fall freeze falls around no reliable fall freeze; see the note, USDA zones 4b-10b, 8,014 growing degree days in the year.
Heat, not frost, is what shortens the season here: above 86 °F tomato pollen goes sterile, so growers run a spring crop and an autumn one rather than a single long season. Garlic is the awkward one: only 0 weeks below 40 °F, where it needs six to split into cloves. Chill the cloves before planting, or grow a softneck type.
Elsewhere on the property in Arizona: the pests that turn up here.
Figures from NOAA's 1991-2020 climate normals. A state is not one climate: elevation, a large lake or the coast can move these dates by two weeks either way, so check your own county with the extension service before you spend money.
Hydrangea pruning in Arizona doesn’t follow the calendar most gardening advice assumes.
Arizona homes cool almost entirely with air conditioning, and most of it runs through central systems rather than window units or mini-splits.
Phoenix’s design wind speed for roofs is 101 mph under ASCE 7-16, the figure that sets nailing patterns, sheathing fasteners and uplift connections.
Arizona has no statewide hedge height law. There is no chapter of the Arizona Revised Statutes that sets a number in feet for how tall a hedge can grow.
In Arizona’s low desert, the answer comes down to soil, not the calendar most lawn guides use.
Arizona doesn’t have a single frost date, because most of the state barely freezes at all.
In most of Arizona, picking time isn’t set by frost at all. It’s set by heat.
In Arizona’s low desert, garlic comes out of the ground by late spring or early June, once the lower leaves have gone brown and the tops have flopped over.
In most of Arizona, the answer depends less on the calendar than on elevation.
Hydrangeas can grow in Arizona, but only if you treat the desert as the limiting factor, not the frost.