Making your own vegetable planters allows you to make a container superior to the plain plastic pots available at the garden center, often for much less money. A self-watering container requires just a little extra time and ensures your vegetables have all the soil moisture and nutrients needed to flourish---even if you forget to water them for a few days. No special knowledge is required to make this type of planter, and you can reuse them year after year, thus maximizing your investment of time.
Purchase two 18-gallon plastic storage tubs. Choose tubs of the exact same shape and ones with straight sides so that one tub slides into the second one.
Turn one tub upside down. Set a 5-inch diameter pond basket on top of the tub near the middle, also facing down. Trace around it with a marker.
Cut out the traced circle from the bottom of the tub. Use a utility knife or miter saw to cut through the heavy plastic.
Set the pond basket, open side up, next to the uncut tub. Mark the top of the basket on the side of the tub. Drill a half-inch hole in the side of the tub beneath the marked line to make an overfill hole.
Set the pond basket next to the tub with the large hole in the bottom. Mark the height of the basket on the side of the tub. Cut off the top of the tub using the marked line as a guide.
Turn this tub upside down and drill a 1-inch hole in one corner of the bottom. Slide this tub into the tub with the overfill hole. Set the pond basket inside and through the hole you cut out for it and slide a 3-foot length of 1-inch diameter PVC pipe into the smaller hole.
Fill the pond basket with soil-less potting mix then water it. Finish filling the rest of the tub with potting mix, until it is even with the top.
Sprinkle 1 cup of granular fertilizer in a narrow strip lengthwise down the center of the tub. Place a sheet of plastic mulch over the top of the tub and secure with a bungee cord or binder clips.
Cut an X in the mulch where each vegetable transplant is being planted. Avoid planting directly in the fertilizer strip. Water every two to three days by pouring water in the PVC pipe until it comes out of the overfill hole.