Building the Raised Planters for the Edible Learning Lab
Our raised planters in the Edible Learning Lab are customed designed for our specific needs. We use short legs so our younger students have good access to the planters. We recommend between 24″ and 30″ for the leg height. We also use shallow planters using 2×8 or 2×10 lumber for the sides to create the depth. For the most part, we are growing greens so we don’t need to waste material and water on deeper planters. But even at 10″ deep, we’ve had great success with indeterminant tomatoes and some root vegetables like radish, beet, and turnip.
Our planters are lined with a commercial grade PVC liner and we have drain plugs installed at the far end so we can let them drain when overwatered.
The large majority of these pieces can be cut at the hardware store for you if you can supply them with the dimensions (see above). Some of the miter cuts may need to be done in-house. Once you have all your pieces cut and ready to go you can begin the assembly. You’ll need a drill with a 1/2″ bit and a 1″ boring bit, a nail gun or hammer, a crescent wrench, and a staple gun if installing the PVC liner.
Assemble the long and short sides of the container on the floor and use a nail gun to tack the box together. Place the plywood over the box and nail about 6″ on-center along the edges.
Set the legs in place about 16″ in from each edge and drill holes for the thru-bolts. Push the bolts through the holes and use the washer and nut to tighten them in place. You may need to lift or prop up the planter box to get to the inside to tighten the nuts.
While still up-side-down install the cross support 2x4s and the bracing. Laying down some wood glue before nailing will help hold everything together better. Drill a 1″ diameter hole in the plywood at one end of the planter for drainage. If you are installing a drain plug, be sure to drill the appropriate size hole for your plug.
Turn the table right-side-up and install the PVC liner or brush on liquid waterproofing. Be sure to cut off any excess length of your thru bolt and file any sharp edges. Also make sure none of your nails are sticking through that could puncture the PVC liner. Install the drain plug at the hole drilled through the bottom of the planter.
Now you can fill your planter with good, organic soil and compost and give it a good watering. Make sure your soil is good and moist before planting your garden. You may have to water it several times and let any excess drain out through the plug.
Be sure to use a heavy plywood for the base to prevent sagging. a good 3/4″ to 1″ plywood should be strong enough to support your planter if you place the legs and supports where we show them. If you do experience any sagging in the plywood, we recommend installing an additional 2×4 support post in the very center of the planter (see below).