How to grow beans

This is the whole crop, and it is where most people go wrong. Our calendar puts beans in a week after the last spring frost rather than on it, and that gap is deliberate: beans want warm soil, not merely air that will not freeze. Sown into cold ground the seed simply rots, and a sowing made a week later routinely overtakes one made on the frost date.

The rule of thumb is soil at about 60°F. If you have no thermometer, the practical test is whether you would kneel on the ground comfortably.

The 1912 manual explains why depth matters so much for this crop, and the explanation is correct botany applied properly. Beans germinate epigeally — the seed leaves are pushed up out of the soil rather than staying below it — and the book notes that a large expenditure of energy is required to accomplish this, and the more compacted the soil and the deeper the seed is planted, the more time and energy are required. Which is why an inch to two inches is right and three is a real cost.

The same fact explains a common panic: a crusted seedbed after heavy rain can trap seedlings that have already germinated underground. Breaking the crust gently with a rake saves them.

Bush beans grow knee-high, need no support, and crop heavily over two or three weeks before winding down. That concentration is useful if you are freezing or canning a batch, and it is why succession sowing every three weeks is the standard advice.

Pole beans climb six to eight feet, need a structure, take a few weeks longer to start — and then crop continuously until frost. For a household eating beans as they come, one sowing of pole beans usually beats three sowings of bush.

Solomon adds a third consideration that only matters in a dry summer, and it is worth quoting the substance: heirloom pole beans once climbed over serious competition while struggling for water, and modern bush varieties tend to have puny root systems. In a garden that will not be irrigated, pole beans are not merely more productive but more likely to survive.

Against that: pole beans need a structure that will stand up to a wall of wet foliage in an autumn wind, and picking the top of an eight-foot row is a genuine nuisance. Both types are worth growing.

Like peas, beans fix their own nitrogen through root nodules, so a nitrogen-rich bed gives you a magnificent leafy plant and disappointing pods. Feed the bed for the crop before, not for this one.

What they want is drainage, warmth and a soil that is not acid. Phosphorus and potassium help; nitrogen does not.

Beans are shallow-rooted and dislike disturbance, so hoe carefully close to the plants and mulch rather than cultivating deeply once they are established.

Water matters most at flowering and pod set. A plant that dries out while flowering drops its flowers, which is the usual explanation for a bean plant that looked healthy and then simply did not produce.

A bean plant exists to make seed. Let a few pods swell and mature and the plant reads its work as done and stops flowering — so picking is not just harvest, it is what keeps the crop going.

Pick snap beans while the pods are slim and before the seeds inside show as bumps. That is earlier than most people pick and it is the difference between a tender bean and a stringy one. Modern varieties are bred stringless, but even a stringless bean goes tough and leathery if left.

Pick every two or three days at the height of the crop. Missing a week during a warm spell can effectively end a bush planting.

Use two hands. A bean pod is attached more firmly than it looks, and yanking one-handed tears whole shoots off the plant.

If you find over-mature pods, take them off anyway and compost them. Leaving them costs you far more than they are worth.

Slugs take seedlings, particularly in a damp spring, and this is the commonest cause of a gappy row. Beans emerge with large fleshy seed leaves that slugs find very attractive.

Black bean aphid colonises growing tips in early summer. Pinching out the top few inches of an affected shoot removes most of a colony and does the plant no harm.

Halo blight and bacterial blight show as water-soaked or yellow-haloed spots on leaves and pods in wet seasons. They are seed-borne, so the practical answers are buying clean seed, not saving seed from an affected crop, and not working among the plants while the foliage is wet.

Bean rust appears as orange-brown pustules on leaf undersides late in the season, usually as the crop is finishing anyway.

And the failure that is not a pest at all: flowers that form and drop without setting pods, which is almost always heat above about 90°F or drought at flowering. It corrects itself when conditions ease.