I would suggest getting 1 5gallon sized atrovaginata that has as many culms as possible meaning it has already been through a shooting cycle in the pot. Several plants will eventually compete for light and get too dense while a single larger plant will make larger culms right off.

I bought a 2 gallon atrovaginata off bamboo gardens last year which had 3 culms all just a bit over 2ft tall. This spring, it put out 10 upsized culms which range from 5-7ft in height and rhizomes have spread as far as 7ft away this summer so I'm expecting a straight up grove by next year.

If you buy one now, chances are you might be getting a more developed plant that was hopefully up-potted from a smaller pot size since those perform the best and if you tarp it over with plastic from December through March, I don't think it should leaf burn. My atrovaginata did not get protected and it got through several nights of single digits here without leaf burn, but I don't know if it gets colder in your area so I would suggest protection.

I agree with Stevelau on this one. The larger the plant you start with the faster it will spread and the faster it will put up large canes. Small plants take forever to spread and mature out. Plus you'll be able to dig off of them sooner. To spread your grove even farther. 3 years versus 5 for the smaller ones. A good 6-9 ft tall plant with 3 or more canes will spread 5-10 ft in one year. A small pot with 2-3 canes 3 or 4 ft tall may only spread 3-4 ft if you're lucky. The bigger the plant the more energy it has. A small plant usually means small rhizomes. Small rhizomes put out small canes. Large rhizomes put out large canes. The bigger the rhizome the more energy it has stored inside. Always choose the bigger plant. Hope this helps. I've been growing for 10 years and have 29 different species. Atrovaginata is very hardy. I just got mine about a month ago. It was getting ready to be sized up to a $65 dollar pot I got it for $45 its about 8 ft tall with about 6 canes in it. The grove it came from had some 3 inch diameter canes that were amazing I can't wait. It was a steal. Brad Salmon at Needmore Bamboo really took care of me and gave me some great deals. And the plants were all very healthy. I got six new species and they are all in the ground and looking great. Good Luck

I think the difference between a 2 gal. and 5 gal. is probably a year, but they're not directly comparable. Put that 2 gal. in the ground one year, and the next year you'll have a larger plant (more culms, taller, more spread) than the 5 gal. pot has right now.

I think I agree with Steve -- the 5 gal. will size up faster than the 2 gals. Not sure about spread though.

Try and find out when in your area the soil temp reaches 40 F. That's the cutoff temp for root growth that you read most often. I think you're ok to plant 6 weeks (or is it 4?) before that date in order for the plant to be established enough to survive the winter -- provided it's cold-hardy enough to begin with.

Do not grow it indoors. That won't help and will most likely set the plant back a bit I think.