Cowpea Growing Calendar: What to Do at Each Stage

The shape of the cowpea year

Cowpeas occupy the hottest part of the year and nothing else. The season starts when the soil passes 65F (18C) and rising, not when the frost date says it can, and it ends either when picking has exhausted the plants or when the crop has dried down for seed. In between there are four clearly marked stages, and each one asks something different of you.

The first three weeks are slow and unimpressive above ground while the taproot goes down. The next three or four weeks are rapid growth and, in climbing types, vine run. From about week seven flowering begins, and this is the single stage where water and attention matter most. From week nine onward you are either picking every second day for young pods, or letting the last flush dry down.

Because the whole cycle is short, cowpeas fit well as a second crop after early potatoes, garlic or overwintered greens, and equally well as a summer green manure on a bed you want improved rather than cropped. In climates with a long hot season, two sowings comfortably fit.

Setting the sowing date by counting backwards

For a snap-pod crop the sowing date barely matters as long as the soil is warm, because you can pick until the weather turns. For a dry seed crop it matters a great deal, because the last three weeks are a drying-down period that needs dry, breezy weather. Rain on ripe pods splits seed coats and sprouts seed inside the pod, and a crop that looked finished can be lost in a wet fortnight.

So work backwards. Find the last settled dry stretch of your year, count back about a hundred days from the end of it, and check whether the soil is warm enough at that point. If it is not, either accept that you are growing for green pods rather than dry seed, or find a way to bring the crop in early and finish the drying under cover.

Succession sowing changes the arithmetic for snap pods. Three short sowings three weeks apart gives you young pods continuously from the first sowing's peak through to the last, rather than one heavy glut and then nothing.

1. Identify the dry weeks you are aiming at For dry seed, the last three weeks of the crop must fall in settled dry weather. Pick that window on the calendar first, before you think about any other date.
2. Count back a hundred days Ninety to a hundred and ten days covers sowing to dry seed for most cowpeas. Count back from the end of your dry window to find the latest sensible sowing date.
3. Check the soil will be warm enough by then If that date falls before your soil reliably reaches 65F (18C), the dry-seed plan will not work this year. Grow for snap and shelling pods instead, which have no such constraint.
4. Split the bed by intention Mark which stretch of row will be picked young and which will run to seed, and mark it physically with a stake. Once pods are forming, the two look identical and the decision gets made by accident.
5. Book the trellis job into the first week For climbing types the support has to be standing before the seedlings are three inches (8 cm) tall. Put it on the calendar as a sowing-week job, not as something to do when the vines start reaching.

The decisions that actually come up

Three judgements recur every season and each has a clear answer. The first is whether to water: the honest rule is no water at all until the first flower buds show, then a deep soak weekly through flowering and pod fill, then nothing once the pods have reached full size. Leaves folded shut at midday are normal heat behavior; leaves still folded at dawn mean the plant is genuinely dry.

The second is whether to feed. The answer is almost always no. A cowpea with working nodules supplies its own nitrogen, and added nitrogen buys leaf at the expense of pods and pulls in aphids. The only exception is a row that has gone uniformly pale by week five with white or gray nodules, where a single light feed is a rescue rather than a routine.

The third is when to switch from picking to letting the crop dry. Picking young keeps flowering going, so the longer you pick the longer the plant produces, but a plant still being picked in cool, damp autumn weather will never dry a decent seed crop. Stop picking about six weeks before your weather turns, and let the pods already set run through to dry.

If the season turns wet while pods are still filling, pull whole plants once the pods are full sized and hang them under cover. Seed that has reached full size will finish drying off the plant; seed left out in the rain will not.

Clearing up and what the crop leaves behind

Cowpeas are one of the better things you can do to a tired bed, and how you clear them decides how much of that benefit you keep. The nitrogen the crop fixed sits in the root nodules, so cut the plants off at ground level and leave the roots in the soil rather than pulling them out. The tops go on the compost pile unless the crop showed blight or leaf spot, in which case bin them.

Used deliberately as a green manure, the crop is cut and dug in at full flower, before any pods form. That is the point of maximum nitrogen in the plant, and turning it in then rather than after cropping puts far more back into the soil. It is a real trade: you get the soil improvement or the harvest, not both in full.

Whatever follows should be something that wants the nitrogen. Leafy greens, brassicas and sweetcorn all do visibly better on a bed that grew cowpeas. Do not follow cowpeas with another legume, and keep at least three years between cowpea crops on the same ground so that the soil-borne rots and any nematodes do not build up.

The record that makes next year's calendar

A cowpea calendar written for a region is a rough guide; a cowpea calendar written from two seasons of your own notes is a working plan. The dates worth capturing are the ones that mark transitions, because those are what everything else hangs off: sowing, emergence, first flower, first pick, and the day three quarters of the pods went tan.

Add the soil temperature you measured on sowing day and the weather during the drying-down weeks, and you have enough to set next season's dates without guessing. Note which bed the crop occupied as well, so the rotation stays honest, and note what you planted after it so you can see for yourself what the nitrogen was worth.