Flower Seedlings Flopping

[Marb67]

All my so far healthy flower seedlings that have come up are starting to flop over for no reason after a week. Metal Tray is on a heat mat for germination with brand new seed sowing compost (sieved) and new plastic seed modules. It can't be lack of water as have kept moist so absolutely no idea why this is happening. It's bad enough not many have come up. Various seeds from new to at most 3 years old.

[Andraste]

I'm thinking 'metal tray' is going to conduct heat & combined with the heat mat I'm wondering if you might be cooking/overheating them?

I had this happen on a larger scale with strawberry plants at the plot I tried in a metal container - the top growth looked great but the sun warming the metal meant the roots were getting cooked so they never thrived even though you'd think they'd like the heat. Made it tricky to get the moisture levels right too as they dried out really quickly.

[Marb67]

Well I've taken them outside and even more are falling over. Oh the joy!

[Andraste]

Be careful they don't go into shock from being indoors on heat to straight outside. I'd be tempted to either keep them off the heat mat indoors for a little bit or move them to a greenhouse in the day but bring them in at night as temps are still dropping too low overnight for a lot of tender stuff just yet.

[Nicos]

I struggle with heat mats and seed trays in that all seedlings need removing from the heat as soon as they germinate…but then it’s just one or two modules and you are waiting for the rest, then the earlier germinated start to bolt and have longer, thinner stems before the first set of leaves…making them very vulnerable to stress factors and tend to flop over.

I’ve no idea how people manage full trays of different types of seeds, all germinating at the same time.
I do wonder if you early germinating ones have bolted. And keeled over in the heat…and then stressed by the cold.

I tended to put smaller module trays on the mat and pull them as soon as they show signs of germination.
It took me a while to realise that heat mats are only supposed to be used for germination…..but I’m happy to be corrected by someone who regularly succeeds with heat mats.

[Marb67]

I bought the seed trays as I thought it was a great economical (money and space) way of sowing many things in one aea. Clearly not

[Nicos]

Are you able to cut them into smaller strips so they still fit , but you can take sections out when they are ready?

[Marb67]

Are you able to cut them into smaller strips so they still fit , but you can take sections out when they are ready?

Possibly, I'll have to have a look and see thanks.