Types of Mist Irrigation Systems Recommended in Poly House

Overhead Systems

• In overhead misting systems, lines or sprinklers are installed under the roof framework of your poly-house, and these "rain" water down onto your plants. This type of irrigation system is easy to automate and produces high humidity. This high humidity allows you to protect crops against frost damage. For the best coverage, space overhead sprinklers to around 50 to 60 percent of the wetting diameter of the sprinkler.

Bench Misting

• Bench misting uses a central line of sprinklers or hoops placed at or just above the level of your plants. Bench misting requires plants to be placed on raised benches, and these must be made of materials that are impervious to water, such as a metal. You can also use a self-contained misting bench, in which the bench is partially covered with a "roof." This allows you to have just a single misting bench in the poly-house, and a different watering system in the rest of the poly-house.

Benefits

• Both types of misting system are well suited to plants that need to be kept moist, such as seedlings, and to reducing temperatures in a poly-house. Misting is commonly used for propagation and for growing tropical plants that require constant humidity. Some misting systems can also be used to spray fertilizers evenly and finely. Fertilizer applied this way is more easily absorbed into the plants than fertilizer applied on the soil. By allowing you to vary the humidity within the poly-house, mist systems also allow you to vary the temperature and control the growing conditions.

Drawbacks

• It can be easy to over-water with either type of mist irrigation system. To prevent this, you can use a timer to turn the water on and off. Misting nozzles have very fine holes that can clog up if you have hard water. Misting also works best if your poly-house is completely enclosed, as a breeze can disrupt the fine spray and cause areas to remain dry. Misting may not be suitable for all types of plants, so if your poly-house contains many different types of plants, with different water tolerances, you may need to water each type of plant individually, or use individual benches, rather than use an overhead mist irrigation system.