The brief venture into passive hydroponics was not met with a great deal of success. In early review, it seemed like an optimal system for easy closet cultivation. A passive hydro system can be built with minimal expense. Recycling two-litre bottles as planters was a novel idea. A cat litter box can be purchased at any grocery store for about five dollars. The system was built.

It failed miserably.

This article details the design of a new system, the transplanting process, and cultivation methods used through to harvest.

Passive Hydroponic Root Rot

The concept of passive hydroponics is to constantly oxygenate a stagnant nutrient solution. You bring the air to the roots rather than bringing the water. While this works well for some plants, marijuana is particularly demanding in its roots' need for oxygen. This system failed to provide enough air for the roots to breathe. When the roots are drowned, they quickly brown and rot. Nutrient solution in the reservoir becomes toxic and all plants are traumatized.

Adding to the development of sickly roots is rapid evaporation of the uncovered nutrient pool. When the water evaporates, salts and minerals are left behind. The total dissolved solid (TDS) count in the solution rises at a rapid rate. pH balance is impossible to maintain in the small wildly fluctuating reservoir. These imbalances cause a lock-out which prevents the plants from making use of the nutrients in the solution and stunts their growth or causes their outright demise.

Designing the New System

A new system which could revive the existing crop and make use of the available space was immediately required. The plants were already rooted in rockwool blocks and surrounded with Geolite. There was no way to separate the rootball from the grow rocks without major damage, so the new system would have to support the existing core.

Since Geolite is primarily used as medium in a large particle ebb&flow style system, this was the first consideration. However; long-term goals, plumbing issues, and financial contraints proved the logical choice to be a drip irrigation system. The drip system is easily expandable, it could be mobile if necessary, and it is suitable to support the future intentions of using rockwool slabs.

The basic principles of drip irrigation are simple:

• A reservoir at lowest point holds nutrient solution.
• Solution is moved up through a main irrigation tube by a water pump.
• Feed lines to each plant are connected to the irrigation tube by drippers.
• A stake holds the end of each feed tube over the plant.
• Solution drips down into and through the medium.
• Gravity draws solution down to the reservoir through a recovery system

Gathering Supplies

Most of the necessary supplies to complete this project are available at any large hardware store. The few items which were purchased at a hydroponics store could probably be replaced with improvised materials, with the exception of hydroponic nutrients. This is a basic list. Items from a garden supply shop have been marked with an asterisk (*).

• Lumber for ramp construction and light mounting
• Black plastic sheeting for lining
• One gallon pots as containers
• 10 gallon "under-bed" storage container as reservoir
• 75 gph pump
• Main tubing and irrigation line *
• Drip emitters and stakes *
• Geolite * and Perlite
• 5" funnel
• Heavy Duty timers for pump and light
• Miscellaneous screws, clamps, and brackets