Muskmelon (cantaloupe) should be harvested when the rind changes from green to tan or yellow between the outer netting, and the stem slips easily from the fruit.
Summer squash should be harvested while fruits are young and tender-skinned, 6-8 inches long or 3-4 inches in diameter for round types.
Sweet corn is best harvested when kernels are plump and tender and yield a milky juice when pressed with your thumbnail. Kernels that are past their prime tend to yield thick, doughy pulp, while immature kernels will yield a watery juice.
Cool and Moist Storage (45-50 degrees F)
Cucumbers are best harvested while immature and before seeds have a chance to fully develop. The timing will vary with the cultivar. Most slicing cultivars will be 1 1/2-2 1/2 inches in diameter and 5-8 inches long. Pickling cucumbers will be short and blocky, compared to slicers.
Eggplants are best harvested when fruits are nearly full grown but while they are still immature; they get seedy rather quickly. Eggplants are not adapted to long storage.
Green bean pods will be most tender when the small seed inside is one-fourth mature size and not yet visible from the outside. Past this stage, the pods become more fibrous as the seeds mature.
Okra should be harvested daily as young, immature pods when they are 2-3 inches long; the pods get woody if allowed to mature on the plant.
Peppers, both bell and hot types, are usually green while immature and red, or some other color, as the fruit matures. They can be harvested when fruits are firm and full size. Picking them while green will encourage further flowering and fruit set. If red (purple, yellow or orange for some varieties) fruits are desired, leave on the plant until color develops.
Potatoes can be harvested as “new” potatoes, before maturity, if they are going to be consumed right away. If storage potatoes are desired, harvest after the tops have yellowed and/or died back. Carefully dig the underground tubers, and then cure (air dry) for about a week in a shaded, well-ventilated place (open barn, shed or garage). Remove excess soil from potatoes, and discard those that are diseased or damaged. Avoid exposing tubers to light; they will turn green with even a small amount of light. Store in as cool a place as possible but above 40 degrees F. Ideal storage conditions are hard to find in late summer - cool basements are often the best storage available. Keep humidity high and provide good ventilation.