Plants
Choosing a plant for your zone
A hardiness zone tells you whether a plant survives the winter. It does not tell you whether it will flower — that turns on when your last spring freeze lands, and on whether the type you picked was holding its flower buds when it arrived. These pages separate the two.
-
Hydrangea
3a–9b
Why your hydrangea has leaves and no flowers, answered against your own zone’s measured last spring freeze.
-
Magnolia
4a–10b
Which magnolias open before your last freeze date, and which wait until after it.
-
Dogwood
2a–9a
Flowering dogwood against kousa, judged on your own zone’s measured last spring freeze.
How to read these
Each page carries two kinds of figure and keeps them apart. Zone ranges and bloom habit are a judgement — horticultural convention, the same standing as the heat ratings on our crop tables. The freeze dates are measured: NOAA 1991–2020 climate normals, ranged across every station the zone’s own ZIP codes cite rather than one station picked to speak for it.
⛔ We publish no temperature at which a flower bud is lost. NOAA’s normals give dates, not damage thresholds, and inventing a number to bridge the two is the one thing this site refuses everywhere else.
For edible perennials — fruit trees, nuts, berries — see what survives my winter, which runs the same zone arithmetic over a separate table of 74 plants.