Each Planter Well will irrigate 9" of soil beyond its edge, so one 20" Planter Well reservoir will keep the soil moist in a window box or planter that is 38" long.
Rules Of Thumb for the 20"L x 6"W x 2"H Planter Well Reservoir
Using One (1) Planter Well
20"-38" Interior Length x 6"-12" Interior Width x 7"-12" Interior Height.
Using Two (2) Planter Wells
43"-67" Interior Length x 6"-12" Interior Width x 7"-12" Interior Height.
Using Three (3) Planter Wells
66"-96" Interior Length x 6"-12" Interior Width x 7"-12" Interior Height.
