T4.2 Root Collar Diameter

general - root collar diameter - cell grown trees - seedlings, cuttings and transplants - stem diameter - girth

The Root Collar Diameter is defined as ‘‘the diameter of the main stem measured at or within a specified distance from the root collar.’’ The root collar is between the base of the aerial part of the plant and the top of the root system.

The collar is generally a lighter colour than the stem, except for trees of the genus Juglans, where the opposite is true.

The Root Collar Diameter may be specified for Seedlings (especially Cell grown trees), and cuttings and transplants, particularly where these are used as rootstocks.