I just bought this romaine plant. It has about 5 heads really close together. Do I have to untangle them and plant them separately? Or do I leave them be? I was going to put them in a bigger box, 8x6in, but do I need something bigger because it's more than one?
I think you can separate in multiple potted plants. If you wish so, you can leave them as they are, fertilizing them often when needed. It doesn't matter what you do, it's going to bolt anyway sooner or later. Separating them and leaving them to grow individually will drain less nutrients as each plant will have ample nutrients from soil as well as more room for roots to grow. Also, by the look of it, a majority of your lettuces are way past its preferred tenderness, they will probably taste bitter or unappealing (i.e. bolting). So harvest the most tender ones and leave the older ones to go to flower. That way you'll have 100s of seeds to regrow them the upcoming season.