Please define normal conditions? Normal conditions here in central Mississippi aren't going to be the same normal conditions in say Illinois.
So they won't just break down on you within 3 years. But obviously they are fabric, so a 200 gallon bag for instance, after year 2, might not be a good idea to be dragging it around full of soil. Basically just common sense type stuff. Since we sell heavy duty stuff everywhere else, we just say normal conditions to relate that these are still just fabric bags that will last you 3 years, unless you're doing something a bit too aggressive or unusual with them. Hope this helps!
If you buy more than 20 are there fixing on them?
Yes you can buy more than 20 grow bags. Just submit a request on our contact form with the details and we can give you custom order pricing: https://www.bootstrapfarmer.com/pages/contact-us
How do these bags hold up against gophers? Will they chew through the bottom?
Good question which im afraid I don't have a definitive answer. It takes a lot of effort to rip the fabric. I imagine a gopher would need to put some effort into it but it could get through.
These are made out of a leach free food safe polypropylene fabric woven plastic. A gopher could probably chew through but it would not enjoy doing so. We have never heard of anyone mention that they had a gopher chew through yet. If this was something you were really concerned about you could line the bottom with hardware cloth which is a steel mesh available at any hardware store.
Would either the 100 or 200 gallon bags be good / deep enough for root crops such as beets, carrots, parsnips, etc?
Yes either one would work nicely. 100 gallon might be better since you'll have to move less dirt. Just remember to replenish soil with organic material such as compost after harvest to keep soil healthy for next crop.
How will you know when the bag is done with it's use? Will the bag start decomposing, and if it does will it leach any chemicals into the soil?
We've only had to replace our bags just because they will look worn after a while. If aesthetics aren't a huge concern, and you leave the pot be, they will last a long time. After a few years, if you move them around to much, they'll eventually just rip.