Gardening guides
Plain-English explanations of the data behind this site, with original analysis and links to the original sources and Cooperative Extension publications.
- How to read your hardiness zone — and what it can't tell you
What the USDA zone number and a/b letter actually measure, how to read plant labels, and why cities in the same zone can have frost seasons months apart.
1,417 words · updated October 19, 2026 - Frost dates explained: what 10%, 30% and 50% really mean
How NOAA computes last and first frost dates, how to read the 10/30/50% probabilities, frost vs. hard freeze, and which date to use for each crop.
1,342 words · updated October 19, 2026 - Why the 2023 hardiness zone map looks warmer
What changed in the 2023 USDA zone map, with our ZIP-by-ZIP comparison of the 2012 and 2023 PRISM listings, and what it means for gardeners.
1,213 words · updated October 19, 2026 - Microclimates: why your yard's frost date isn't the station's
NOAA stations a few miles apart can differ by weeks in frost dates. How cold-air drainage, walls, water and pavement shape your garden's microclimate.
1,226 words · updated October 19, 2026 - Succession and fall planting: counting back from your first frost
How to calculate last sowing dates for fall crops and plan succession plantings, with worked examples using real frost dates for Denver, Akron and Atlanta.
1,251 words · updated October 19, 2026