Grow bags are cloth bags typically made from thick, non-woven, pressed fabrics. In most cases, a thick (7+year) landscaping fabric is used. The non-woven fabric aspect allows for free air circulation around the roots allowing them to absorb water and nutrients more efficiently. As the plant’s root comes against the wall/air pockets at the sides of a fabric pot, they will self prune themselves. This allows for a much healthier root system that does not get root bound like in traditional plastic pots. As the roots are self-pruning, transplanting from a fabric pot will do less harm to the root system. Some non-traditionally transplanted plants with fragile root systems can be safely transplanted when using fabric pots.

Grow bags come in a variety of sizes, from one gallon to hundreds of gallons. Common sizes include 1-gallon size for single smaller plants and 5 to 7 gallon for tomatoes/peppers. With few exceptions, the 5-7 gallon fabric pots will grow nearly anything in your garden, including most varieties of squash. In some cases, like Giant pumpkins, they may not grow in the bag; however, they will let you transplant a fully grown plant from a 5-gallon fabric pot into the ground, increasing the growing season drastically.

Lettuce and smaller leafy greens can be grown as single plants in one-gallon fabric pots; 5 Gallon pots will grow a single plant of most types, including tomatoes. I’d recommend going up to 6 or 7 gallons for tomatoes – or even up to 10; I use 6-gallon pots that work well. A single squash plant will grow well in a 5-gallon pot (except the larger ones – Hubbard/giant pumpkins). Even root vegetables like beets and carrots can be grown as long as the pot is deep enough and the plants are spaced properly.

There are many pros to growing in bags, the largest, in my opinion, is that they can extend our growing season.

Pros:
They can be used anywhere – inside, out, patio, driveway—no need for much space or tilled soil.
You control the soil quality – if you have bad soil, then buy and fill your bags with quality soil.
Easy to use and move around. Plant on shelves, racks, steps, anywhere. If it gets cold, bring them inside for the night.
Breathable bags prevent root bounding.
Cannot overwater
Regulate heat much better than plastic.
Easy Storage.
Less/no weeds.

Cons
Durability – they tend to last a few years.
Must be watered regularly (daily in summer).
Must feed regularly (bi-weekly/monthly).
Larger ones can get heavy.
They dry out quickly.

Bags of various sizes are available online as well as in some local shops. They range in price from a few dollars for a five-gallon pot and up for larger pots. The more heavy-duty the bag, the longer the bag will last and typically, the more expensive it is. It is also possible to make your own grow pots of various sizes using heavy-duty landscape fabric and UV protected (outdoor) upholstery thread.

When picking landscaping fabric, try to get as thick as possible; 7-year or 25-year are typical ratings, with the 25-year being much thicker. Non-woven landscaping fabric is available in 32 inches or 36 inches wide by 25,50,100 and 300-foot rolls. A five-gallon cloth bucket requires around 26 inches by 36 inches to give you an idea of how many you can make on a roll.

A few folds, some pins and some sewing, and you have your own buckets ready to go. A design plan for making your own grow bags if you feel so inclined.
Items required:
Thick Landscaping Fabric
UV stabilized (outdoor) upholstery thread
Good Pair of scissors
Chalk pencil or something to mark on the landscaping fabric
Measuring tape
Sewing Machine and someone who can use it

The design plan is for one-gallon pots; however, the initial cut of 25″ by 36″ is the five-gallon pot size dimensions needed. To make a five-gallon pot, use a full 36″ wide by 25″ tall instead of the 25″ wide by 12″ tall in the pictures. The corresponding dog ears for five-gallon bags will be 6″ to 7″ to allow the bag to stand.
The dog ears are the most difficult. They are stitched perpendicular to stitch and fold ends; refer to the picture of a one-gallon pot. If the ears are to narrow, then the pot won’t be square and will fall over; if too wide, the bottom will be more “pointy” and fall over.
Once your bag is done, fold it inside out and fill it with soil to test it out. If you are happy with the final product, go ahead and make some more.