I noticed that not much has been written on the issue of growing tomatillos in containers, and after growing some from seed this March, I now know why. I grew four tomatillo plants, but only three survived past transplanting. The one that did not survive broke at the main stem due to insufficient lateral support. I thought that this was an isolated incident perhaps due to improper light levels leading to a leggy plant. Then this month my more robust and almost tree trunk looking plant had its fruit bearing stems break off due to the weight of so many tomatillos.
The bottom line, cage tomatillo plants in containers and guide the stems with twine. The plant will try to expand laterally. Do not let this happen. Instead guide them so that they grow vertically. I have been doing this for about three weeks now with good results, my tasty salsas can prove it. Oh, and before I forget, I grew these bad boys in five gallon containers. I water kinda often, so maybe next season I will use 15 gallon containers. I would like to know if anyone else has given this a try.