RADICUMS: These plants are special in that their stems have roots that will cling as they grow vertically or grow over the ground. Ivy is a good example.
RAISED BED: Elevated garden bed offering better drainage, soil aeration and warmer soil than a conventional garden bed.
REED: Tall grasses that grow in shallow water.
RELATIVE HUMIDITY: The measurement of the amount of moisture in the atmosphere.
REMONTANT: Repeat bloomer. Plants that will bloom more than once a year.
RESTING PERIOD: The time when a plant has naturally stopped growing but when there is little or no leaf fall. Comparable to dormant period.
RE-SEEDING: Plants that drop their seeds for next season such as wildflowers and weeds.
RESTING PERIOD: The period of dormancy where energy is restored to the plant.
RETICULATE: Marked with a branched network of veins or fibers.
RETAINING WALL: A wall that has been built on a slope to keep the soil from sliding or eroding.
REVERT: Sometimes a particular cultivar might change back to one of its original species.
RHIZOME: An underground, horizontal stem.
ROCK GARDEN: An area constructed of larger rocks arranged to look natural.
ROCKWOOL: This really is the state of the art rooting medium, and is used in plant propagation.
ROOT BALL: The network of roots along with the attached soil, of any given plant.
ROOTBOUND: A condition which exists when a potted plant has outgrown its container. The roots become entangled and matted together, and the growth of the plant becomes stunted.
ROOT CROPS: Any vegetable that the roots are edible: i.e. carrots, potatoes, beets.
ROOT CUTTING: The root is used for propagation.
ROOTING HORMONE: A chemical in powder or liquid form which promotes the formation of roots at the base of a properly prepared cutting.
ROOT ROT: Quite common in plants that are effected by fungus diseases and have poor drainage.
ROOTSTOCK: The root onto which a scion or bud is grafted or budded.
ROOT ZONE: The entire area where roots are growing below the plant. Root zones are important for walking paths and future plantings.
ROSARIAN: Those hobbyists or professionals who specialize in the cultivation of roses.
ROSETTE: Term applied to a whorl of leaves arising at the base of a plant.
ROTATION: Specifically towards crop rotation: changing the plants in the same growing area. This will decrease the soil born diseased.
ROTENONE: Material used by a lot by gardeners. It is derived from the roots of tropical legumes.
ROW COVERS: Several types of semitransparent materials used to cover plants, trapping heat, enhancing growth, and provide protection from frost or winds.
RUGOSE: Rough and wrinkled.
RUN: A plant that runs will be growing rapidly underground. Great for ground cover but some plants take over an area by running.
RUNNER: A slender stem growing out from the base of some plants, which terminates with a new offset plant. The new plant may be severed from the parent after it has developed sufficient roots. Strawberry plants develope runners.
RUNOFF: When liquids build up and wash off quickly, a run off is created. Often pesticides and fertilizers are washed into waterways in this manner.