Step 1: Materials, tools and build time
*1 burlap coffee sack. Feed sacks and food aid sacks work, too, as would any large bag.
*3 cubic feet of soil. We used organic compost, but a soil-manure mixture would work, as would compost from an ecological toilet, a household waste compost bin or any nutrient-rich soil.
*Gravel. *A large yogurt container with the bottom cut out. Coffee cans or other similar-sized containers also work.
*Starter plants. We planted serrano and habnero chiles, sweet potato, sweet pepper and two kinds of basil.
*Trowel or shovel (optional)
We spent about one hour gathering the materials and 1.5 hours putting it together the first time. It could go much faster once you know what you're doing.
Step 2: Begin making the center column of gravel and fill the bag
Start by putting a shallow layer of soil in the bottom of the sack, place the yogurt container (or coffee can or a similar container) in the center and fill it with gravel.
Shovel the soil around the rock-filled container and fill out the sack to the edges. When the soil reaches the top of the container, pull it up gently, leaving the rocks in a column in the center. Repeat until the bag is full with a center column of gravel. The column is for drainage and water distribution throughout the sack.
Tip: In hindsight, wire mesh (ckicken wire) or (maybe) a wide PVC pipe (or some other material that makes a cylinder) would make it easier to create the central column of gravel. Shape the wire into a long cylinder, put it upright on the bottom of the bag, fill it with gravel then fill in the bag with dirt around the thing. You could leave the wire mesh inside when you're finished. And if you used a PVC pipe, you would have to pull it out when the bag is full of dirt.
Step 3: Plant it
Plant the top of the sack. You can plant herbs, veggies, flowers or whatever you want that you think will thrive in this space.
Tip: Try putting root crops on top and leafy vegetables and herbs in the sides.
Step 4: Plant the sides
Cut a small hole in the sack for planting along the sides.
Tip: We cut the holes too big. Try making a small cut that looks like an upside down "T," then scoop out soil from below the cut to make a little shelf for the plant.
Step 5: Ta da!
Finished. We settled on six plants, but a sack this size could hold more. Now, you just have to water it, keep it in a sunny spot and cross your fingers.