Peas are a rewarding crop, but they are not for the absent-minded gardener. Into the ground they must go, as soon as the soil has lost its winter sogginess, so they can make their growth during cool spring weather. Most need some sort of support, even the “bush” type, to keep the vines clean, upright and easy to pick. (I like nylon string netting, but any mesh — or even leafless birch branches stuck in the ground — will do.) They need an inch of water per week to keep the pods growing.

But it’s harvest time that really demands your attention. With leaf, stem and root crops you can be a little casual, picking a few outer leaves from a kale plant, pulling off a stalk of young celery and even robbing a hill of potatoes for delicious little spuds as soon as the flowers appear. Fruiting crops, on the other hand, have a time window — a month or so if the fruit is an apple, at most a week if it’s a tomato, and a mere blink of an eye if it’s a pea.

Today’s pea-growers are blessed with three options when deciding what type to plant. All are wonderful, and all have specific criteria of ripeness you must watch for. The classic green pea (often called English pea or garden pea) is picked when the seeds have fully formed inside the pod, which happens 20 to 30 days after flowering. Look closely at the pod with its inner seam facing you and you’ll come to know just how fat and rounded it must appear before the peas are worth gathering. This stage lasts, at most, two days, before the peas toughen and lose their sweetness. You can confirm this by tasting them, but the eyes and fingers tell a quicker tale. The surface of the pods will turn rough and lose their shiny bright green color.

Fortunately, not all the peas in the patch will ripen at the same time, and you can stretch the harvest to a couple of weeks as long as you keep up with the picking. If you stop, no new pods will form. Try to pick them every day. They’re best eaten immediately but will retain their sweetness — the reason we grow peas — for a few days in the fridge.

With the Asian-type peas, often called snow peas, you don’t let the seeds get round. They are edible-pod peas, but only when the pods are very flat, so that you can feel only the slightest little bump of seeds inside. These are great in stir-fries, or raw in salads, and if you’ve ever bought them in the supermarket and found them limp and tasteless, you’ll realize how important it is to catch them at the right moment and then eat them promptly.

Barbara Damrosch’s English peas. (Barbara Damrosch)

The snap pea is a more modern addition that was created by crossing the two types described above. Known as sugar snap peas (the name of a seminal variety), they’re eaten pod and all, even after the peas have swelled — the best of both worlds. Busy cooks love them because their sweetness is a bit less elusive and because they don’t require shelling. Everybody loves them for their crunch. A simple bowl of them set on a table is a celebration. But when it comes to picking, they wait for no one.

Damrosch’s latest book is “The Four Season Farm Gardener’s Cookbook.”

Tip of the week

Moonvines, or moonflowers, should be started from seed now for their spectacular and fragrant white trumpet blooms, which appear in late summer. The vines need sturdy support and can be used on railings, trellises and fences, in full sun or light shade. Rub seeds against a metal file or soak them overnight before planting, to speed germination.

— Adrian Higgins