One calculator, three planting seasons
Most gardens have three planting windows, and each works differently. Spring planting counts forward from your last frost: hardy crops can go in before the last frost, while tender crops must wait until the danger has passed. Summer planting is for heat-lovers that need warm soil to start and enough time to mature before fall. Fall planting counts backward from your first frost so cool-season crops finish before the cold sets in. Pick the season above and the calculator switches both the math and the crop list to match.
Spring vegetables: what to plant after the last frost
Spring is the busiest planting season. Cold-hardy crops like peas, spinach, lettuce, and onions tolerate cool soil and can go in weeks before your last frost. Tender crops — tomatoes, peppers, squash, beans, cucumbers — are frost-sensitive and should wait until after the last frost date, when soil has warmed. The calculator flags which is which so you don't lose seedlings to a late freeze.
Summer planting: heat-loving and succession crops
Summer is for warm-season crops that thrive in heat and for succession sowings that keep the harvest coming. The trick is making sure there's still enough time for the crop to mature before fall frost, so the calculator checks both ends: warm enough to start, with a finish line before the cold.
Fall vegetables: beating the first frost
Fall is the season for cool-weather greens and roots — kale, spinach, lettuce, radishes, carrots, and broccoli. Because days shorten and growth slows, the calculator adds a buffer and counts backward from your first frost to find the last safe planting date for each crop.
Understanding your frost dates
Two dates anchor the whole gardening year: your last spring frost and your first fall frost. Both are regional averages, not guarantees — elevation, microclimate, and a given year's weather shift them. Treat the calculator's dates as a planning anchor and watch your local forecast as each season turns.