Being the first time I wasn't too sure, so I bought all 3" pots.The seeds were started 8 weeks before last frost. Before I was able to move them outside the tomatoes were so large I ended up having to put them in pots for a few weeks. I'm hoping the larger pot and a two week delay in starting the seeds solves the issue. Planning 22 tomato plants this year as compared to 12 last year. I don't have enough room for that many large plants plus the other stuff. If they get too big both the tomatoes and yours truly will be in the garage!