Size guide

 Small: Fits pots up to 16 cm (6 in) high, or all setups (water container and pot) with a height difference up to 13 cm (5 in)

Medium: Fits pots from 11 to 26 cm (4.5 to 10 in) high, or all setups with a height difference up to 23 cm (9 in).

However - its OK to play around!