Windowfarm: how I built a self-watering vertical garden

Guestpost by Kellbot on Apr 19th

Now that we have a place with nice big windows I'm trying my hand at a windowfarm. Windowfarms are drip planting systems that are set up vertically, making them great for places without a lot of outdoor gardening space.

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Two dwarf sugar pea plants.

Windowfarms are made from plastic bottles stacked vertically. A small airpump lifts water from the reservoir at the bottom to the topmost bottle, where it then trickles down over each plant. The plants, which were started in root plugs, are sitting in 3″ net cups filled with expanded clay pellets. The pellets offer root support for the plant, and retain water while still allowing plenty of oxygen flow.

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My set up is, in a word, ugly. Eventually I plan on having four columns hanging in the window, and with any luck they'll get more attractive as I go along.

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I used a large plastic orchid pot to hide the water reservoir, which is simply an upside-down water bottle with a coil of 1/4″ tubing coming out the cap. The blue tray is leftover from a previous hydroponics experiment, and is there to hold the bottle vertically.

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To make the joint between the cap and the tubing water tight, I sacrificed the barbed end of a plastic hose connector and pushed it into the cut end of the tubing. This pushes out the sides of the tubing and keeps water from escaping.

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The water line is about 3 feet long and runs up to a t-joint, which you can just barely see in the photo of the reservoir. Airline tubing from the air pump comes in from the side, and the black tubing carries water up to the top of the plant column.

The basic theory of the system is that water comes up from the bottom and is then pushed up the black drip tubing by air from the air pump. Undergravel filters in aquariums work on a similar principal. Getting it to actually work is a trial and error process, and your reservoir needs to be high enough above the t-joint to keep the water pressure up.

The air pump also needed some tweaking to work well. Too much air and you get a noisy system that doesn't lift water well, too little air and you get a quiet system that doesn't lift water well. I found a nice four-way adjustable valve on Amazon which allows me to carefully adjust the airflow.

The system is on for 15 minutes every two hours, which I'll increase as the plants grow. I've planted dwarf sugar peas, tomatoes, and basil so far. With any luck I'll have something edible in a few months.