Staying alive

Dear Ed,
We want to keep about 20 plants alive for a month without supervision. We don’t need great growth or vigorous plants when we return, but we don’t want to have dead plants. Any ideas?

Closet Cultivator,

First, air circulation and temperature must be managed. Automatic ventilation and thermostat controlled cooling can take care of that. The very high intensity lighting should be placed 20-30 inches (50-70 cm) higher than normal.

There are many ways to deal with water. Plants growing in soilless mix can be watered passively using a wick system. Wick systems are easy to make. Before planting mix is added, several pieces of 3/8-inch woven nylon rope are placed through the bottom holes of the planting container so that they hang out about 7 inches (20 cm). After planting, the container is placed in a tray with sides 5 inches (15 cm) high. The container is raised using a pallet, blocks of wood, styrofoam blocks or other inert pieces. Water is added to the tray and the plants are also watered from the tops of the containers. Once the wicks are wetted, they draw water to the container using capillary action, the same way a tissue draws up a puddle. The wicks replace moisture in the pots as it is used, as long as there is water in the tray to draw from.

A ball valve can be used to replenish water in the tray from an overhead reservoir such as a working toilet tank. The valve keeps a stable water level, opening only to replenish water as it is used.

Hydroponic system reservoirs can be re-supplied with water from an additional reservoir using a ball valve. Watering is controlled using timers or a computer.

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