Knowing when to harvest is an important part of home gardening. It's one of the big differences between the vegetables you can buy and those you can grow. When you grow them, it's possible to enjoy vegetables at the peak of perfection by picking them at just the right time.

With some, it couldn't be easier. Tomatoes, for instance, are generally eaten when they're red and ripe. Some people jump the gun on the season and fry or grill green tomatoes, but most people have no questions about when to eat their tomatoes.

Zucchini is another story. The best zucchini are the young and tender ones, but since there's more profit to selling bigger, tougher ones, that's often the way they come to market. When you grow your own, you can eat them when they're just about six inches long. And you can eat the seeds, peels and all.

Beans have a similar story. They weigh up better for market when they're big, but they taste much better small, before the beans cause the pods to swell around them and toughen. Beans can be eaten any time they're big enough to make picking them worthwhile.

Peppers can also be eaten any time they're big enough, but they pick up more vitamins if they have time to ripen and turn red or yellow. Cucumbers, on the other hand, have to be eaten young. If you allow cukes to get really big and start turning yellow, all you can do is make them into ripe cucumber pickles.

Cabbages are ready when they appear to have stopped growing, and when the heads are good-sized and solid. Broccoli is fussier. It has to be picked young, even it it's small. Otherwise, the flower buds separate and begin blooming, and the broccoli is past its prime. once you pick the first heads, though, let the plants grow for a while. They'll continue to produce smaller heads in the leaf axils. Don't let these flower either. Keep them picked and they'll keep producing.

Summer lettuce has to be eaten young - even if it means continuous planting. Once it gets old and bolts to seed, it gets too bitter. Eat it young. When it passes its prime, pull it out and use the space again.

Root crops, like beets and turnips, can be allowed to grow big for winter storage, but they get tougher. It s the Ping-Pong ball-sized roots that you'll remember as the sweetest you've eaten. Young carrots are much sweeter too. Radishes, like beets and turnips, get woody when old. Their season is so short, though, that they get old much faster.

Onions have to mature to gain keeping qualities. As onions and shallots mature, their leaves turn brown and wither. Wait until the tops are completely dead before you pull the onions. Then set them out in the sun for a day or two, and they'll keep.

Potatoes can be eaten any time they're out there. You can eat them small and new, or let them grow big. If you grow them under a hay mulch, you don't have to dig, or damage the plants to get a few new potatoes. All you have to do is lift the hay and look.

Sweet potatoes are harvested after the vines have died down. Okra can be picked any time it's big enough to eat. So can eggplants and all kinds of summer squashes. Winter squash has to grow until the skin gets tough.

Corn, at its premium, has nothing tough about it. It's best just after the silk has withered and the kernels have filled out. When you peel back a husk, the kernels should be full, and, if you break one with a fingernail, it should release cream. If it gets old, the cream dries out, and it gets tough.

Most herbs are at their height just before they flower, when the concentrations of essential oils are highest. Harvest herbs at that time, but just do it by cutting them back, and they'll flower again before summer's end.

All of this information about when to harvest crops is useful, but if you spend time out in the garden, watching and tasting, you won't need it. Your taste buds have this information coded into them, and they can tell you what to pick when. Just relax and pay close attention to what they tell you. You'll get used to eating vegetables at their very best.