This is one question many have a tough time finding a good answer to.
Knowing the dimensions of the tomato plant would enable you choose a comfortable sized bag for it.
The planting depth of tomatoes is usually 1-2’ and they have a depth (root growth) of 6-8”, bringing the total height for consideration to 10-12’.
From there, you’d see that a 5 gallon or 7 gallons sized grow bag would be suitable for growing one tomato plant.
If you want to grow several tomato plants and don’t want to buy ‘too much’ smaller sized grow bags, you could choose to use the grow bags that look like sacks and come ready with soil.
You could use the larger sizes to grow an amount of two to three tomato plants, while taking into consideration the spacing required by your tomato plant.
Don’t be afraid to try planting in grow bags larger than what is necessary for growing tomatoes.
However, the bag shouldn’t be unnecessarily large unless you want to grow several tomatoes at once like in a really small patch of land.
The same goes for other smaller plants.
Be willing to spend on buying quality grow bags. After all, they don’t cost much and many of them are reusable as long as you wash after use and store them properly.
A little tip…