Use frost dates as a starting point
Start with a measurement
Find last spring and first fall frost information from your local extension or weather source. You choose the dates; this tool does not guess your location or derive planting dates from a hardiness zone.
Worked example
Spring offsets are preparation windows for a frost-season garden. Soil temperature and the forecast still matter. No frost date? Select relative dates to keep the spacing, buying list and before/after-frost windows. Calendar downloads remain unavailable until dates are entered.
Check the real conditions
Fall windows subtract a cultivar maturity range and a 14-day planning buffer from the first fall frost. Warmer summers, shorter days and cultivar differences can move the workable window. Update the inputs and compare actual crop growth with the packet.