width across rim. nice diagram!

As weatherwise says, across the rim. With a 'standard' shaped pot rim and depth are the same but many plants are sold in 'half' pots (half the depth) or long pots.

Thanx WeatherW/BulbA uv helped lots :) Glad u like the Diagram:)

Also, it usually means the diameter of the inside of the pot, Jacque, in case it has a broad brim.

Thanx TugB im learning everyday ;) :)

Not in Rock Garden Club shows, Tugbrethil. If the show schedule says that the size of the pot in a particular class is, for example, 'not to exceed 19cm' then the judges will use a pair of calipers to measure the outside diameter of the pot.

Bulbaholic, I suspect that's just to make sure it will fit on the show table! : )