This section is from the book "The Gardener V2", by William Thomson. Also available from Amazon: The New Organic Grower: A Master's Manual of Tools and Techniques for the Home and Market Gardener.
Few early vegetables are more appreciated than these, and few are of easier culture. Those who have every facility for growing them in pots in forcing-houses, and later on in pits and frames, are not called upon to make extra exertions to forward them on warm borders. At the same time, the sooner the houses and frames are relieved the better, and on this account it is advisable to grow a few Beans as early as possible in a sheltered position. Unfortunately they are very tender, a slight frost completely crippling them. Beans, in common with other seeds, were badly harvested last season, and probably if sown early, taking into consideration the cold wet state of the soil, they will germinate badly. To secure a few pickings, of a certainty, in succession to those obtained with the assistance of a glazed frame, or a rough frame and mats, it will be found the best practice to raise a few plants in pots, and transplant. 3-inch pots may be employed, using moderately rich soil, placing two good seeds oppositely, and near the sides of the pot. They may be placed in a warm house or frame, transferring to a shelf or a cold frame in time to prevent the plants becoming drawn, hardening off, and finally transplanting, if possible, at the foot of either a south or west wall.
Early in May will be soon enough to plant, and even then they will require protection from late frosts. This protection may easily be given at any time, if a few branches of Spruce Fir, or some other evergreen, are kept in readiness. Hand-lights, as they are taken off the earliest Cauliflowers, may also be placed on a warm border, and be each filled with about eight plants in two lines: this of course will forward the Beans considerably. The seed should be sown about three weeks before the plants are required; and if only fifty plants are put out, they will yield several small and acceptable dishes.
To maintain the supply, seed may be sown on a warm border, should the ground be in good working order, about the middle of April, otherwise it is advisable to delay sowing till the end of the month, sowing again about three weeks later, also on a warm border, unless the spaces between the trenches got out for Celery are utilised for the purpose. Osborn's Forcing is the best for the earliest sowings - Canadian Wonder and Negro Longpod forming good successions. Moulding up is sufficient support for the former, but the two latter well repay staking, moulding up then being unnecessary. The soil should be moderately rich for Kidney Beans. The rows may be placed from 24 to 30 inches apart, according to the growth of the variety. On poor sandy soils, the rows of Osborns and other dwarf sorts may be placed 18 inches apart, thinning out the plants to about 5 inches. The stronger growers well repay being given plenty of room, say from 9 to 10 inches apart. All of course require to be kept clean by frequent hoeings.
Watering is seldom necessary; and it is difficult to apply in sufficient quantities on a warm sloping border.