- Raceme
- Along flower cluster on which individual flowers each bloom on small stalks from a common, larger, central stalk.
- Rhizome
- A thickened stem which grows horizontally below or on the soil surface.
- Ringing
- The removal of a narrow strip of bark around the periphery of a stem to obstruct delivery of nutrients beyond that point. It is used to stimulate a fruit to bear.
- Rock Garden
- A garden consisting of low-growing, spreading plants growing among rocks, often set on a slope.
- Root
- The part of a plant, normally underground, that functions as an anchorage and through which nutrients are absorbed.
- Root ball
- Matted roots plus enclosed soil within a the pot of a container grown plant.
- Root bound
- The condition resulting from growing a plant too long in the same container. When there is no room for the roots to expand, they become tangled and grow in circles. These roots must be loosened before transplanting or the plant will not thrive.
- Rooting hormone
- A chemical in powder or liquid form which promotes the formation of roots at the base of a cutting.
- Root stock
- The swollen, more or less elongate stem of a perennial herb.
- Rosette
- Term applied to a whorl of leaves arising at the base of a plant.
- Row Covers
- Several types of semitransparent materials used to cover plants, trapping heat, enhancing growth, and provide protection from frost or winds
- Runner
- A creeping stem which produces small plantlets along its length. Sometimes called a 'Stolen.'
- Rust
- A fungus that infects ornamental plants. Each type of rust is specific to a certain type of plant.Warm days, cool nights and moisture contribute to rust development.
