leggy sunflower seeds

[sacbina]

4 seeds sown indoors 2 weeks ago, all unexpectedly germinated but 2 are a bit, shall we say, limp. probably about 6" fall already but falling over.

they were sown Into big yoghurt pots as the spot they will grow in is not yet free.

dd worried about her sunflowers

Probably too warm indoors, and pots not big enough, or watered too much: or ALL of these!

Are they a good brand of seed? Plant a few more, keep in coolest room, but as much light as possible and no draughts.

spot to grow in should be free this weekend, should I just transplant straight outside our will it be a bit of a shock? would they do ok if I planted them deeply to cover up the stem, a bit like tomato plants?