What causes "Leggy" seedlings?

I planted sunfolwer seeds in cell packs, and now they're tall with a pair of
leaves, some with 2 pairs, but they're staarting to fall over! Too soon to
plant outdoors... should I repot them and stake them now? They're only 2-3"
tall and can't stand on their own?! Is this normal?
Thanks!


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TAKETHISOUT budysbackagain(@)THAT TOO a-oh-ell dot com