How to Tell When to Harvest

Monitor the size of leaf, fruiting and pod-producing vegetables. Harvest most leaf vegetables, such as spinach (Spinacia oleracea), when the outer leaves measure 6 to 8 inches long. Pick fruiting and pod vegetables, such as tomatoes (Solanum lycopersicum) and green beans (Phaseolus vulgaris), when they reach the full expected size for each variety.

Allow the vegetables to reach their full mature color before picking. Most tomatoes turn red or red-orange at maturity. Peppers (Capsicum annuum) develop to a full green, yellow, red or purple depending on the variety. Refer to seed packets and plant labels to verify the mature color. Winter squashes (Cucurbita spp.) grow to their full color and size, and the rind begins to harden, when they reach maturity.

Pick pods, such as peas (Pisum sativum) and beans, when the pods reach their full mature length and the seeds reach the desired stage of maturity. Harvest shell peas when the seeds are firm and full-sized but the pods are still green. Pick snap beans before the seeds begin to swell; harvest dry beans after the pods dry and the seeds rattle inside.

Check the stems of muskmelons (Cucumis melo), and harvest these when they begin to slip off the vine on their own. Harvest watermelons (Citrullus lanatus) and other melons that don't slip when the bottom of the melon, where it rests on the ground, turns yellow.

Harvest root vegetables when the tops die back, as with onions (Allium cepa), or when the visible top of the root reaches the desired mature size, as with carrots (Daucus carota). Dig up one or two root vegetables to verify the size, if necessary.