Drainage

Marijuana Horticulture

by Jorge Cervantes

All containers need some form of drainage. Drainage holes allow excess water and nutrient solution to flow freely out of the bottom of a container. Drainage holes should let water drain easily, but not be so big that growing washes out onto the floor. Containers should have at least two half inch holes per square foot of bottom. Most pots have twice this amount..

To slow drainage and keep soil from washing out of the large holes, add a one inch layer of gravel in the bottom of the pot. Surface tension created by the varying sizes of soil and rock particles cause water to be retained at the bottom of the container. Line pots with newspaper if drainage is too fast or if soil washes out drain holes. This will slow drainage, so be wary!

Put trays under containers to catch excess water. Leaving water-filled saucers under pots often causes root rot. To avoid water logging soil and roots, set containers up an inch or two n blocks when using trays.

Nursery trays used for rooting cuttings and growing seedlings must have good drainage throughout the entire bottom. Once clones and seedlings are in place in the tray, the tray should always drain freely with no standing water in the bottom.