Iceberg lettuces not getting hearts

Never had any success with lettuce in the past, but I found the remiander of a packet of Iceberg lettuce seeds, so I just bunged them all in a seed tray.

Of course they nearly all took, so I have about 20 odd lettuces all coming up at the same time.

My problem seems to be that they aren't forming hearts like proper Iceberg. They have many outer leaves which are all looking good, but no central core of folded leaves.

Could the hot weather recently be tempting them towards bolting?

Having said that they are darker than the light green of an Iceberg, so I suppose I may have planted something else - must learn to label things!

Good question, Aunt Sally.
As well as not labelling seeds I do not keep any records of when things were planted.
My gardening tends towards the "plant it and hope" system.
They were probably planted about 4-6 weeks ago and put out on the plot about a fortnight ago.
Are you thinking I may be jumping the gun and hoping for results too soon?

My mini icebergs take at longer than that to mature Aunt Sallys right there.  Rough guess 70 days.  Depends what time of year planted.  But they (mini green iceberg)stand well, so can plant a few and cut as when.

Thanks Aunt Sally and everyone else.

I thought, being salad stuff, that they would mature a lot faster than that, so looks like I'll have to wait and keep watering.

 :DGetting into gardening more has shown me that you do indeed need patience. I have always had a life of hurry, hurry, hurry (being a sales manager) and at last I am starting to realise that you don't have to rush when gardening. So what if it takes an hour to repot a load of seeds? So what if you have to stand for a while watering things?

I need more patience, anyone know where I can take a crash course?javascript:replaceText('%20:D',%20document.forms.postmodify.message);

When I was a kid my grandfather used to laugh at me because he'd give me some beans or peas to put in a little patch and I was forever furtling to see if they were growing.  I reluctantly admit that there are still times when I do it now.

And we all know what a cruel, fickle boss she can be at times.