Greenhouse hoses are usually three-quarters of an inch in diameter and flexible for easy handling. They must either extend the full length of the benches they are to water or at least reach the center if the water supply is at both ends of the greenhouse. An assortment of nozzles is manufactured for greenhouse use. Some are breakers, which diminish the force of the water but not the rate of flow. Others are foggers, which permit the water to be applied as a fine mist to seedlings and other tender plants. Water should never be applied at a rate of flow that furrows the soil in the bench or the container. To do so creates a condition favoring uneven water absorption thereafter.
When watering, a hose should first be stretched down the aisle to its full length. The crop should then be irrigated while moving with the hose back toward the faucet. Two benches may be watered from one aisle. A pattern of watering should be established and followed so that the technique becomes almost habitual. For example, the nozzle and hose can be extended between rows of pots and both rows irrigated from the rear of the bench forward. Regardless of the pattern, each pot should be filled to the top with water as a means of assuring that each container receives the same amount each time. The technique is
imprecise but the best possible with hand application (Figure 20-10). Hand-watering is more effective with potted crops than bench crops. The rate of application to a bench can be very inconsistent. NOTE: To avoid possible contamination by pathogens, the hose end should rest in a clip between uses. It should not be allowed to fall on the ground. Also, the sun can heat the water in a hose to temperatures that will injure the crop. So let the water run until cool before applying to the plants.