Dismal sunflower record

I sowed 8 plugs of sunflowers 3 weeks ago- Vanilla Ice. Just one has come up and that one looks like it's fixin' to die.

Most years the mice eat them but I'm fairly sure they didn't get them this year because the seed tray was indoors, in the propagator.

I don't recall that I have ever, in my whole life, grown a successful sunflower from seed. Yet they are supposed to be child's play, aren't they?

What am I doing wrong?

 

I think slugs and too much wet weather finished most of mine off up to now so ive popped some more( mixed types) in pots and just put seeds round the garden,fingers crossed i got double headed chocolate ones last yr but i seem to plant 50 and only get 4 so im not stressing about them this yr.....ive bought vanilla ice seeds previously but never seen one
I do have some mexican sunflower which seem to be doing ok so far,ive only lost half of them up to now

 

Yea they are suppose to be really easy lol

Try them in pots instead

 

I've grown dwarf ones this year, they've all come up, are planted out and thriving. Sorry to boast!

 

Bah!!
I have got them in pots indoors so it's probably not slugs - well, unless they creep round the dining room while I'm in bed. Anyway, nothing came up for them to eat!

I only sowed 1 seed per pot (cos I'm a right skinflint). Should I be a bit more generous with the seeding? On present showing I'd need 8 seeds per pot to get a result. Also, would the propagator have been too hot? It's ideal for the 68 degrees and above brigade, but maybe sunflowers prefer it a tad cooler?

 

I put one seed in a pot, as they are quite big seedlings when they appear. They were started off in an electric propogator and as soon as they appeared I took them out and put them on a window sill in my unheated porch. After a week there I moved them to the greenhouse, also unheated. They were hardened off three weeks ago outside. I think as seedlings/young plants go, they don't like to much heat.