play4abuck

As others have said they need more sun light or a artificial light source.
You may also be over watering them, use a spray bottle to mist them as
needed.

My broccoli is leggy again this year, as is a one of my tomatoes varieties.
Two years ago this happened and I planted the broccoli anyway, it just laid
on the ground the first 24 hours looking doomed, but it took off after 2
days in the ground.

After you correct the real problem (light/water), you may want to prop the
plants back up that have folded over.

1) Stick 2 tooth-picks in the dirt, in a X pattern, next to the plant to
support it upright.

2) Or cut a large soda straw (like from a fast food place) in half, then
cut the half up the middle, so you have 4 U-shaped pieces. Insert these
pieces next to the plant for support.

I would thin the seeds now, I'm not sure you will be able to separate the
plants successfully before planting, better safe than sorry.

You might start a second batch of seeds, use Seed Starter Plant mix and
paper Egg cartons for a starter tray. When you transfer the plants to the
ground, dig the hole bigger than needed and add some of that left-over plant
mix.

Cheers,
Jim