Greenhouse Management
Glossary
H
HEADHOUSE – Separate or attached building to the structure used as a preparation area.
HEAT TRANSFER COEFFCIENT – A numerical value given to the relative amount of heat transmitted or transferred through a material.
HERBACEOUS – A plant that dies back to the ground in winter and returns again in the spring.
HERBICIDE – A chemical used to destroy undesirable plants and vegetation.
HIGH INTENSITY DISCHARGE (HID) LIGHTS – High intensity discharge lights include both metal halide (MH) and high pressure sodium (HPS).
HIGH PRESSURE SODIUM LIGHTS – High pressure sodium bulbs emit an orange-red glow. This band of light triggers hormones in plants to increase flowering/budding in plants. They are the best grow lights available for secondary or supplemental lighting (used in conjunction with natural sunlight).
HOOP GREENHOUSE – Hoop houses are constructed from bent tubular pipe for the framework, which is then covered with some type of plastic. Hoop houses are low cost alternatives to even span structures. Hoop houses are often used as temporary holding houses or long term growing structures.
HORIZONTAL AIRFLOW FANS – These fans are hung from the ceiling and are positioned to blow air in one direction down one side of the greenhouse and in the opposite direction down the other side of the greenhouse.
HOTBED – A hotbed is a miniature greenhouse that is heated to protect new seedlings from cold. The hotbed differs from a cold frame in that it has an internal source of heat while the cold frame is heated only by the sun.
HUMIDISTAT – A control for the operation of a fogging or misting unit that operates on the relative humidity content of the air.
HYDROPONICS – The culture of plants in root substrate consisting exclusively of water and dissolved nutrients.
HYPHA – A single filament of a fungus.
