ROCKERY: A mound made of rocks that have the spaces in between them filled with soil. It is usually used for planting small, choice plants that need quick drainage, such as ferns or alpines.
ROGUE: 1. A plant that falls short of a standard of horticultural quality required by nurserymen, gardeners, etc. 2. To uproot or destroy, as plants which don't conform to a desired standard.
ROOT: The part of a plant, normally underground, that absorbs nutrients and anchors the plant into the ground.
ROOT BALL: The roots and soil or soil mix that they are growing in when lifted from a container or the open ground.
ROOT CUTTINGS: Some plants are easily increased by root cuttings. Root cuttings are made by cutting off pieces of root, each about 3 inches long, and planting them in a frame, greenhouse, or outside.
ROOT GRAFTING: The process of grafting scions (shoots) directly on a small part of the root of some appropriate stock, the grafted root being then potted.
ROOTING COMPOUND: A powdery substance into which fresh cuttings are dipped before inserting in soil or medium, containing hormones to encourage root growth.
ROOT PRUNING: Cutting the roots of large plants, mainly trees and shrubs, to force more vigorous growth or to prepare the plant for transplantation.
ROOTSTOCK: 1. A robust plant which provides the root system in grafting. Also known as a stock. Scions and buds are grafted and budded to a rootstock or stock. 2. The elongated and often thick rhizomes of certain perennial herbaceous plants such as the Iris, Aspidistra and Solomon's Seal.
ROOT ZONE: The part of the soil in which plant roots grow.
ROSARIAN: A cultivator of roses; a rose-grower; a rose-fancier.
ROSE FORM DOUBLE: Describes a flower with imbricated petals (laid like roof tiles) showing stamens in a concave center when open.
ROSETTE: A group of leaves radiating from about the same point, often at ground level at the base of a very short stem, or at the tip of longer stems.
ROSTELLUM: Part of the median stigma lobe of Orchid flowers.
ROTATION OF CROPS: A recurring series of different crops grown on the same ground; the order of recurrence in cropping. It's found that the same kind of crop can't be grown on the same soil several years in a row with good results. Therefore, a different kind of crop is made to follow the one before it in repeated series. (Different soils and climates require different systems of rotation.)
ROTENONE: A broad-spectrum botanical insecticide derived from several tropical plants. One of the stronger and longer lasting botanicals. Also fairly toxic, especially to fish.
ROW COVER: Any of various types of semi-transparent materials that are draped or supported by hoops over vegetable crops. They increase growth, provide frost protection, and exclude pests.