Greenhouse Management



ABCISSION – The normal shedding of a senescent plant part or organ (e.g., old leaf or ripe fruit).

ACRYLIC – A plastic greenhouse covering consisting of two layers of material separated by air space to provide insulation.

ACTIVE INGREDIENT – The chemicals in a pesticide product that controls the target pest.

ADJUVANT – Chemical added to a pesticide formulation or tank mix to increase its effectiveness or safety.

AERIAL ROOTS – Aerial roots are roots that are above ground.

AGGREGATES – The structures, crumbs, or clumps formed when soil minerals and organic matter are bound together with the help of organic molecules, plant roots, fungi, and clays.

ALKALINE – The opposite of acidic; having a pH greater than 7.

AIR INFLATED – Separation of two layers of flexible film by sealing the edges and inflating with pressurized air.

AMENDMENT –  Any material, such as peat moss, processed bark, and sand, added to a
growing medium to improve its ability to support plant growth.

AMMONIFICATION – The biological process by which ammonium is released from nitrogen-containing organic matter. Ammonification is nitrogen mineralization.

AMMONIUM – A form of nitrogen (NH4+) that is available to plants and is produced in the early stage of organic matter decomposition.

ANION – A negatively charged element or molecule such as chloride (Cl–) or nitrate (NO3–).

ANNUAL – A plant living one year or less, usually planted in the spring after the last frost. During this time, the plant grows, blooms, produces seeds, and dies.

APICAL DOMINANCE – The inhibition of lateral bud growth by the presence of the hormone auxin in a plant’s terminal bud. Removing the growing tip removes auxin and promotes lateral bud break and subsequent branching, usually directly below the cut.

AUXILIARY BUD – The bud that forms in the angle that the leaf makes with the main stem.

AUXIN – A group of hormones that induces growth through cell elongation.