Planting cubes, a convenient way to start seeds indoors, tend to be overpriced. Rather than paying a premium, reuse some items you may have around the house to create a planting cube form. Once you've got the form maker, you can create hundreds of planting cubes with little effort. Then sow seeds in your cubes, and when seedlings are ready for the garden, just place the whole planting cube in the ground. Be sure to cover them completely with garden soil.
Create Cube Maker
Use the box cutter to cut the top off one bottle so that it is about 25 percent deeper than it is wide. For example, if you have a bottle with a 2-inch diameter, cut the bottle to 2 1/2 inches tall.
Cut the bottom off the second bottle so the diameter or perimeter is about an 1/8 inch smaller than the cut bottle.
Set the flat piece inside the cut bottle and use the soldering iron to melt holes through the center of both layers.
Assemble your planting cube maker by first putting one washer and then a nut on the bolt. This forms the handle. Insert the bottle with the hole toward the nut you have just added. Put on another nut and screw it about halfway up the bolt. Add a third nut right next to the second.
Put on a washer and then the flat piece of plastic (from Step 2) to form the plunger piece. Put on a third washer and then the last nut so about one thread from the screw is sticking out past the nut on the end.
Place a drop of glue between each of the pieces that hold the plunger in place and tighten the nuts around the flat plastic piece using pliers. Tighten the nut on the handle piece as well, after adding a dab of glue between the handle washer and nut.
Making Planting Cubes
Add water to the potting mix until thoroughly moistened. Firmly pack moistened soil into the block-maker.
Press the plunger to push the block out onto a planting tray.
Repeat until you have the desired number of planting cubes. Then proceed with planting. Sow seeds in the divot made with the tip of the bolt.