Grow bags are plastic bags filled with potting soil that can be used to plant an assorted range of plants. Although you can manufacture your own grow bag using potting soil and a plastic bag, you can just as easily plant transplants or seeds directly into a store-bought bag of potting soil for an instant grow bag. One popular novelty using grow bags is to suspend them from hooks to make upside-down tomato plants.
Inspect a bag of potting soil before purchase to ensure that there are no tears in the bag.
Choose potting soil in at least 5 -gallon increments. A single tomato plant requires at least 5 gallons of potting soil to thrive.
Puncture multiple tiny drainage holes into the bottom of a bag of potting soil with an ice pick. An ice pick will create holes large enough for water drainage, but not so large that that soil will leak from the bag.
Turn the bag over so that the drainage holes are on the underside of the bag. Cut an X-shaped slit in the top of the bag. The slit should be large enough to accommodate the stem of a tomato plant.
Strip away the lower limbs of the plant up to the tomato's topmost true leaves. Hollow out a planting hole in the bag deep enough to cover the root ball and stem of the tomato plant. Drop the tomato plant's root ball in the hole and fill in around the root ball and stem with soil. The tomato plant will put out new roots wherever you removed a branch.
Water the grow bag so that the soil remains as damp as a wrung-out sponge.