Garden Vegetable Yield Calculator

A well-tended home garden in zone-matched soil hits between 0.3 and 3 lb per square foot per year, depending on the crop. Tomatoes commonly land in the 1 to 3 lb range when staked and pruned, zucchini can reach 3 to 5 lb because each plant produces dozens of fruits over a long season, and dense root crops like potatoes return 1 to 2 lb of tubers per square foot. Leafy greens like lettuce and spinach are much lighter per square foot (0.3 to 0.5 lb per harvest) but get a multiplier from succession planting, since you can cut, regrow, and reseed two or three times in a single year.

The 1.4x expert multiplier in this calculator covers a stack of small habits that compound over a season. Experts build soil with compost and cover crops so it holds water and nutrients better, prune tomatoes and peppers for airflow so fruit ripens evenly, scout for pests at the first leaf damage instead of waiting until plants are stripped, and time transplants to soil temperature rather than the calendar. Beginners typically lose about 40 percent of potential yield to a combination of under-watering, overcrowded spacing, late frost transplants, and pest damage that goes uncaught for too long. The math is symmetrical: beginners run at 0.6x of the intermediate baseline, and experts at 1.4x.

Yes, with succession planting. Lettuce, spinach, kale, and other cool-season greens mature in 45 to 60 days, which leaves room for a spring planting (March to May harvest), a midsummer break or shade-cloth cover, a fall planting (August seed for October harvest), and in mild climates an overwintered bed under row cover for a March cut. Many gardeners cut outer leaves rather than pulling the whole plant, which stretches a single planting another 4 to 6 weeks before bolting. The calculator caps lettuce, spinach, and kale at three harvests per year because that is what most US zones realistically support without a heated greenhouse.

Mel Bartholomew published Square Foot Gardening in 1981 and rewrote the playbook for small-space vegetable growing. Instead of long single rows with paths between them, you build a 4 foot by 4 foot raised bed, divide it into a 16 square grid, and plant a different crop in each square at a density set by plant size: 1 tomato or pepper per square, 4 lettuce or bush bean plants per square, 9 spinach or beets per square, or 16 carrots, radishes, or onions per square. The method usually triples the harvest per square foot compared to traditional row gardening (Bartholomew's own benchmark) because every square foot is productive and there are no wasted paths. The yield-per-square-foot numbers in this calculator are anchored to that intensive style of growing.

Each crop has a temperature sweet spot. Tomatoes, peppers, eggplant, and melons need hot days and warm nights to ripen, which is why the calculator gives them a 1.2x bump in warm climates (USDA zones 8 to 10) and a 0.8x penalty in cool ones (zones 3 to 5). Lettuce, spinach, kale, broccoli, and other brassicas bolt and turn bitter in heat but thrive in cool weather, so they get the mirror image: 1.2x cool climate bonus, 0.9x warm penalty. Moderate climates (zones 6 to 7) handle most common crops without much penalty either way, which is why they sit at 1.0x across the board. The calculator's recommendation flags when your chosen mix matches the climate well, and when it does not.