The “Square Foot” Container Garden

OK. What I am going to introduce to you is some square foot gardening things that I have been doing. My wife and I homeschool and one of the things we started was to begin a “square foot garden” as promoted by Mel Bartholomew. I originally built a two-foot by two-foot container garden so it was easy to demonstrate square foot methods at homeschool presentations. However during practical use in the back yard it would dry out quickly.

I constructed an improved model for demonstration purposes. It featured vertical garden netting for climbing vines and I could wheel it around like a wheel barrow. It was more practical as far as demonstrating but again it would dry out quickly during real use in the backyard.

The Cistern Garden Is Born

The thought came to me to put a little water reservoir on the bottom as has been done in other container garden designs. I assembled a secondary container to be attached beneath the box I had made for the garden bed. I used plastic sheeting to line the box for retaining water. I cut a hole for a two-liter pop bottle in the center of the top container. I drilled additional smaller holes for drainage allow air to reach the root systems. Then I prepared a two-liter bottle by cutting off the top portion where it meets with the cylindrical portion. Finally I drilled a hole in the bottom of the bottle to be covered with landscaping fabric placed inside the bottle.

I inserted the two-liter bottle into the garden and filled the garden with dirt. This design would wick the water into the soil and watering would be more manageable for my little container garden. However the garden still dried out and it still did not do so good. I had to keep filling the reservoir until I put a plastic liner in the upper container. So that was my first experiment in square foot gardening and the development of the cistern garden.

The Production Models

My next model was for production purposes in the backyard. It is a four-foot by four-foot model. This garden is placed on a very strong and sturdy stand. The water reservoir and the moist soil is very heavy and the garden cannot be moved without emptying it. I do not want this to fall on my little children or myself or someone in a wheelchair. An accident of this nature would be serious and possibly fatal. The stand will be checked annually and fixed immediately if any deterioration is found.

Also underneath my production garden I decided to put some soil mix and I am going to grow some shade tolerant plants. I put some wintergreen in there and I hope to enjoy some this Fall.

My largest cistern garden is my four-foot by eight-foot garden. The stand that it sits on is screwed and glued to maximize the strength of the structure. I started a mushroom garden underneath so I hope it will do well in such a protected area. I have a series of videos available on my youtube.com channel. Just search for “cistern garden”. You may just want to see the main assembly video for the 4'x8' garden: Garden Assembly Video

Winter Preparations

Over the winter I watched for ice damage from expansion in the cistern. Although the plastic garbage can under the downspout suffered damage from having been left full of water during the winter, the wooden frame of the cistern garden seemed to have stretched to accomodated the expanding block of ice. I refrained from mulching some mint that was growing in one of my cistern gardens and it had a hard time recovering from the winter. I will likely purchase some sheets of polystyrene insulation to cover the sides of the garden structures. I will place a mulch of compost on top of the garden and wrap the whole thing in a black plastic sheeting covering. I have a compost thermometer with a long probe that I can use to check the internal termperature of the garden throughout the winter. A great research activity for home educators this winter!

Design Purpose

The cistern gardens that I have designed are meant to be bed gardens about waist-height so that tending the plants can be done without bending too far over for those who prefer to work mostly upright. The design is also meant to accommodate those who prefer to work sitting or are confined to a wheelchair. The watering is done solely by adequate rainfall or by filling the cistern as needed during drought.

Design Costs

So how much did this experiment in gardening cost? The cost ranged between five and eight dollars per square foot. The cost of the material used in making the four-foot by eight-foot garden totaled to around $187. (Keep in mind that the costs for bulk supplies, tools, electrical power and labor are not included in the cost of each garden but only the materials actually used.)
The tools I used to get started are as follows:

• Power Saw $33.00
• Quick Square $3.00
• Flexible Steel Rule (Tape Measure) $4.00
• Driver Bit
• 1/8" Drill Bit
• 2 Saw Horses (home made) $12.58 each
• Chalk Line $4.00
• Framing Square $5.00
• Level $5.00
• Utility Knife $4.00
• Jig Saw $20.00
• Power Drill (for drilling and driving) $20.00
• Cordless Drill (for drilling) $40.00
• Paint Brush $5.00
• Staple Gun

Approximate Startup Tools $200

I had to buy materials in bulk and they are as follows:

• 3/4" plywood 4'x8' $16.50 per sheet
• 8" boxcar siding 8'$6.50 per board
• 2"x4" pressure treated 8'$2.30 per board
• 2"x4" untreated 8'$1.50 per board
• Angle clips (metal brackets) $0.98 each
• Titebond II exterior wood glue$7.50 per bottle
• 1lb. 3/4" all purpose screws$4.00 per box
• 5lbs. 1 5/8" all purpose screws$12.50 per box
• 5lbs. 3" all purpose screws$12.50 per box
• Staples for staple gun
• 8 mil plastic sheeting 8'x100'$65.00 per roll
• 1 mil plastic sheeting 9'x250'$20.00 per roll
• landscape fabric 4'x80'$16.00 per roll
• 1gallon contact cement (54 sq. ft. per qrt)$21.00 per can
• duct tape 30'$1.50 per roll
• 3/4" Extruded PolystyreneR-4 below grade 4'x8'$9.00 per sheet
• sphagnum peat moss 2 cubic feet$6.00 per bag
• vermiculite 4 cubic feet$29.00 per bag

Approximate Startup Supplies$350

Thankfully I had many of the tools already. Of course I had to buy beverages in two-liter bottles and drink them but I did not include these costs since they are minor. Perhaps I will have garden parties in the future and buy plenty of two-liter beverages to serve my guests as they help me assemble my next garden.

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