Probably nothing. The iceberg types grow lots of leaves ( like a cabbage)before forming the head in the center.

Sounds like buttercrunch and iceberg. Iceberg lettuce can be trickier and is why a lot of people don't grow it. It is quite normal for the first leaves to splay outward. Cabbage grows the same way and the head is formed by later leaves who, in succession, bend in and eventually form the tighter head.

I am looking at your zone number and wondering how far along this crop is. I don't do iceberg every year and only save it for the years when I can get it planted very early and it has an adequate cool season to grow. Iceberg doesn't like heat and can bolt rather easily. I start my iceberg in a greenhouse early and it's set out in transplants instead of direct sowed because it takes a rather long season for it to mature and most of that season needs to be cool. So I guess I'm asking how long our crop has been in ground? If not very long, keep watching it to see if the later leaves don't start to curl in to form heads. If it's been in ground a long time, and your weather is heating up.........it's more at risk for not developing heads and bolting.

Summertime is a good iceberg for growing where the weather heats up.

I'm in Central Maryland and we've had a really wierd spring. I planted these in Mid-March but I also planted them in partial sun because I didn't want them to heat up too much.

So far, we haven't had any really really ho weather for extended periods. I only have 3 iceberg plants growing, just to see how they turned out. I figured it couldn't hurt to try.

They take up a lot of space, which is another reason home gardeners often don't grow them. Unless they have room, they won't head properly.

No, it certainly doesn't hurt to try. Partial shade is a good hedge for your bets. It can be done, and like ltilton says, some varieties are better than others for holding up in heat. Space is not an issue for me for planting, but I have put iceberg in potager situations just to get them out before our main garden goes in. This year they are loving it in a tiered bed usually reserved for annuals on a little hillside near my kitchen. Prolly have three dozen in and cranking along. When I start harvesting them I'll pop a petunia in the empty hole. Head lettuce, especially organic head lettuce, never really gets cheap here and is 100% shipped in. It's a crop with high dollar return for people who eat a lot of greens, and that's what I like to grow.......crops who give me back as high a return on my investment and work as possible.

Another thing, just back from the lettuce rows - iceberg seems to grow more slowly at first, so it can take longer to maturity with the desirable heads. The IB seedlings in my garden are all noticably smaller than the other varieties.

But this year, with the extra month of growing time, looks like it will be a good season for it. I'm expecting to get some nice heads. If all goes well.