YES! I have grown for many years and use 5 or 6 gallon buckets for growing indoors. I see a big difference in plant size and yield, regardless of fertilizing, in buckets with more than 1 plant in them. If I'm not mistaken, I believe that roots tend to keep other roots from competing, so the root mass might be smaller. I'm really not sure of the reason, but I have repeatedly noticed smaller plants and lower yields when growing more than 1 plant per bucket, regardless of feeding. FWIW, I have noticed a difference between plant size and yield between identical plants grown in a 5 or a 6 gallon bucket...again, regardless of feeding. Strange, but true... at least with my experience.