There are many important reasons for transplanting: (i) Some crops can be matured much earlier by starting the plants in hotbeds or greenhouses, transplanting in about a month and finally setting in the open ground. (2) Operations are concentrated. It is much less expensive to combat weeds, insects and diseases on a very small area than in a large field. Then, again, it is less expensive to water and to give the plants the necessary care when confined to a small plat. (3) On small areas ideal conditions can be provided for the growing of delicate plants that require nursing. (4) The ground to be used is often occupied with another crop, hence the necessity of growing plants elsewhere and of having them ready at the proper time. (5) A more ramified root system is developed. In lifting the plants, some of the small, tender roots are broken, and branching occurs to a greater extent. Severance of the roots is therefore regarded as an advantage by many practical gardeners. There are instances, of course, where it is a decided disadvantage. (6) Some writers claim that transplanting increases the earliness of certain crops, which if frequently shifted produce their salable parts sooner than if grown without transplanting. The tomato is a notable example. The theory is, that a frequent disturbance of the root system induces fruitfulness and hastens maturity.
Transplanting may or may not be a severe operation. When plants are pulled, and stripped of all soil and fine roots, it is extremely severe and often results in the death of the plants. If the shift is made with considerable soil adhering and very few roots broken, there may be no retarding of growth. While root pruning is sometimes desirable, it should as a rule be practiced as little as possible. Plants which have a great many small, fibrous roots can usually be transplanted without difficulty. To this class belong cabbage, tomato, lettuce, eggplant, pepper, parsley, celery, onion and some others. It is difficult to successfully transplant pea, bean, corn, beet, turnip, radish, melon, squash and other vegetables, because they have relatively few fibrous roots. The transplanting of these crops is simple enough, provided their roots are not disturbed, hence the popular practice of starting some of them in pots and other receptacles and of shifting without disturbing the surrounding soil.
Transplanting is decidedly more successful in humid climates than in arid regions. It is difficult in many parts of the West to transplant to the field because of low humidity and of drying winds.