Published on Organic Gardening (http://www.organicgardening.com)

Step 4: Square Up

Use the angle to square the two assembled sides. The center strips should be at a precise 90° angle to the horizontals.

Source URL: http://www.organicgardening.com/learn-and-grow/step-4-square

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[1] http://www.organicgardening.com/towerstep4jpg