I'm growing Cosmos from seed for the first time this year and mine are pretty leggy which I'm attributing to the fact that they didn't have enough light from an allround source. I thought I'd plant a few more and see if they get on any better with a more even light source. I'll be interested to see what anyone else has to say.

Like Gaia said99 times out of a hundred, long and floppy means too little light. since the human eye adjusts to the light level, almost the only way to be sure of getting sufficient light is to use a light meter, or remember what worked last year. Cosmos is particularly sensitive because it is such a sun lover.

I've grown cosmos from seed very successfully for the last few years and kept the seedlings in my little unheated plastic greenhouse where they get bright daylight until around 4.00 pm when the sun moves behind a mountain. Mine are sturdy and around 2" high at the moment and I will be planting them out during the next week, protected with plastic-bottle cloches. Perhaps if you start hardening them off by putting them outside during the day they may get sturdier instead of taller? :o)

Thank you all for your comments they are in a utility room which is bright and they have been out when its sunny but they just keep growing and flopping!!

Sorry, Neellan, but I wouldn't be surprised if the room only looks bright to your eyes. In order for the seedlings to get enough light, that utility room would need to have a large (at least 1/2 m larger than the flat they are in) window, which faces east, south, or west. The window should not have more than 1/2 m of overhang, eaves, or awning shading it. There also should not be shade trees or buildings blocking the direct sun from the window. The seedlings should be smack in the window, not on the shelf 3 m away.

In short, sun, sun, and more sun--the seedlings need a minimum of 6 hours of direct sunlight a day, almost every day, from the hour they emerge, to keep from stretching out and flopping. An hour or two outside when the weather cooperates just doesn't cut it. Failing ample sun, keep a full spectrum fluorescent tube or two shining on them for at least 12 hours a day, no more than 1/3 m away from the seedling tops.

Once they flop, it is difficult, if not impossible, to bring them back. Maybe one out of ten can turn its head up, thicken its hair-thin stem up, spread its leaves, and grow normally. Usually, it's better to start over again with new seeds.

Drat, having to bear bad news again!

AW my poor wee things it all started so well, I have more seeds I normally
sow them straight into the garden... back to that then I guess or a greenhouse on the shopping list lol
Thankyou for that Tuqbrethil I'd rather know so I don't make the same mistake again I'll keep the Utility room for the laundry as intended!