Harvesting Mung Beans: Picking Over Black Pods Before They Shatter

Why this crop is picked over, not harvested

Mung beans ripen unevenly on purpose. A plant carries flowers, young green pods and fully black pods at the same time, and it goes on doing that for three to six weeks. There is no single day when the row is ready. Anyone who waits for one gets a row of empty split pods and a scattering of beans on the soil, because a ripe mung bean pod dries, twists and springs open, flinging its seed out.

So the harvest is a routine rather than an event. Every two or three days through the ripening period you walk the row and take the pods that have gone from green through brown to black and feel dry and brittle between finger and thumb. Twist or snip each one off at the stalk; pulling can tear the branch, and a torn branch stops producing. Leave everything still green or only part colored, because those pods are still filling and will be ready on your next pass.

In hot dry weather the gap between a pod being ripe and a pod shattering can be as little as two days, so during the peak of the crop this becomes an every-other-day job. In cooler or duller weather it stretches out and you can go three or four days between passes. The cue is the pods themselves: if you find split pods or loose beans on the soil, you are going round too slowly.

Pick in the morning while there is still a little dew on the plants. Slightly damp pods shatter far less in your hand than pods picked in the dry heat of the afternoon, and the difference over a whole season is substantial.

The picking routine

The whole thing takes ten minutes on a home-sized block once you have the rhythm, and doing it properly is the difference between a jar of beans and a disappointing handful. The two rules that matter are to carry a container you cannot spill from, and to keep the pods you pick each visit dry and separate until you are sure they are fully hard.

Expect to make eight to fifteen passes over a crop before the plants stop producing. The first few passes yield very little, the middle ones yield most of the crop, and the last ones are mostly a matter of clearing up. When new flowers have stopped appearing and the plants are yellowing all over, take everything left including the part-colored pods and finish drying them indoors.

1. Walk the row every two to three days More often in hot dry weather, less often in cool. Loose beans on the soil under the plants mean your interval is too long and pods are shattering before you reach them.
2. Take only fully black, brittle pods Twist or snip at the stalk rather than pulling. A pod that feels leathery rather than papery is not ready and will not store well if you take it now.
3. Collect into a lidded tub or a deep bucket Pods pop as you handle them and a flat basket loses beans over the edge. A tub with a lid also means you can set it down mid-row without a gust emptying it.
4. Spread each picking out to finish drying A single layer on a tray in a warm airy place indoors for a few days. Do not tip fresh pickings straight into a sealed jar with earlier ones; any residual moisture spoils the lot.
5. Clear the plants when flowering stops Take every remaining pod, green ones included, and dry them under cover. Cut the plants at the base and leave the roots in the soil for the nitrogen in the nodules.

Shelling, drying and storing the beans

Dry pods shell easily and need no equipment. For a small quantity, rub them between your palms over a bowl and the pods split and release the beans. For anything larger, put the dry pods in a pillowcase or a lidded tub and tread on it or beat it against a step for a few minutes, then lift out the empty pod cases by hand. Winnow the remaining chaff away by pouring the beans slowly from one bowl to another in front of a fan on its lowest setting, or outdoors on a breezy day.

The beans must be genuinely dry before they go into a jar. The test is a thumbnail: a properly dry mung bean is glassy hard and will not mark, while one that dents is still around 14 percent moisture and will mold in storage. If in doubt, spread the beans on a tray in a warm airy room for another three or four days and test again. Do not dry them in direct sun on a hot day, which cracks the seed coats and ruins them for sprouting.

Store in airtight glass jars somewhere cool, dark and dry, labeled with the year. At the right dryness they keep for several years for eating and stay good for sprouting and sowing for three to four. Watch the jar for the first two weeks: any condensation on the inside of the glass means the beans went in damp, and they should come straight back out onto a tray. Freezing a sealed jar for a week before shelving it kills any bean weevil eggs laid in the pods before harvest, without harming germination.

Picking them green instead

You do not have to take the crop to dry seed. Mung bean pods picked while still bright green and plump, at around three to four inches (8 to 10 cm) long and before the seeds harden, cook as a slender snap bean with a distinct flavor of their own. They are thinner and slightly more fibrous than a snap bean bred for the job, so pick them younger than you think and cook them briefly.

Picking green also changes the plant's behavior. Removing pods before the seed matures keeps the plant flowering, so a row picked green produces for longer than a row left to ripen. That makes a reasonable compromise on a small plot: pick the earliest flush green while the plant is at its most productive, then let the later pods run through to dry seed for storing and sprouting.

The shoots and young leaves are edible too, cooked like any bean leaf, but take them sparingly and only from strong plants.

What to record at harvest

Note the date of your first picking and the date of your last, and count how many passes you made. That span is the real length of the ripening window where you garden, and it is the single most useful figure for planning next year, because it tells you whether one sowing is enough or whether the season has room for two.

Weigh the cleaned dry beans and write the weight next to the row length you sowed. A home row gives a jar rather than a sack, and a bean that costs very little to buy is not grown to save money; the honest reason to grow it is your own seed to sprout, and a weight per row tells you exactly how much row you need to keep yourself in sprouting seed all winter.

Also note how much shattering you saw and after what weather, and set aside the best beans from the healthiest plants as next year's seed before you start using the jar.