Some products are simply not suitable for use in a container. Without being surrounded by all of the complex physical and chemical activities goings on in an outdoor (garden) soil, they often turn to something like cement or muck. Terrific for the garden, but terrible for containers. Also, any packaged product that is especially labeled for garden use had been done so for good reason. The manufacturer knows that it just won't work in a pot. Compost is almost always one of those ingredients that can cause problems when used as a potting soil. It simply turns into a terrible prisoner when under confinement. To take a step backwards and address your other question, it's a terrific idea to start iceburg in containers. For one, you can space the young plants properly in the garden when it's time to plant! Iceburg shouldn't be crowded. Germination flats or pots should be kept warm until the seeds have sprouted, then the plants prefer to be grown on in much cooler temperatures. For germination, soil temperature is what matters, not air temp. Good luck to you, and I hope you take a look into the Growing From Seed Forum here in the GardenWeb.

It is just called "Lettuce, Iceberg" By "American Seed", and has been certainly showing red pigment right from the start, although compared to my "flame" lettuce, it is not quite so red. Now that I look at the package again, the picture looks like a plain old grocery store head of iceberg. I don't think it is too cold, it has not been below 60 in my seedling room, usually mid 60's, I would think lettuce would like that. My "winter cos" lettuce is all green, as it should be. Seed starting is so fun, I will try and update later on what it turns out to be.

I am confused, are you saying that the cultivar "Great Lakes" headed up but a cultivar labeled "Iceberg" did not? There are over a hundred cultivars of iceberg type lettuce of which several are named Great Lakes. There are three of the older cultivar that actually have Iceburg in the name. If that is the case I would continue to go with the Great Lakes or a try a more modern cultivar. It may be that the cultivar labeled Iceberg was a generic cultivar that is not suited, or has a longer growing season etc. But if the cultivar Great Lakes heads satisfactorily go with that as your base line.

Sure it gives you a head start. It allows you to plant an established transplant at the proper time rather than just planting a seed and waiting for that seed to germinate etc. DTM = days to maturity or to harvest so one has to have a plant to plant first right? The given DTM of a variety assumes one recognizes that you have to add 6-8 weeks to that for germination of the seed and the seedling to develop. This is true whether you start indoors or direct seed in the garden. First there has to be a plant. DTM is approximately (DTM is just a general guide at best) when that plant will mature and be ready to harvest. If I put the plants out in march, they will have to stay there until June. Our temps are WAY too warm and they will be bolting by the end of May. And that is one problem with iceberg lettuce - its long growing season. So you can either plant it outside much earlier then March (which in zone 8 should be easy to do either with or without protection on freeze nights), or plant it in a final container that can be moved in and out as the weather permits, or grow it in a greenhouse like the commercial growers do, or plan to artificially shade it outside as the weather warms, etc. That's why most southern gardeners grow leaf lettuces instead as they have half the DTM of iceberg. Dave