I'm not sure because I have not experimented with that process outside. I do have seed heuchera come up in my gardens but not too often(zone 7). My greenhouse was only about 55-60 at the time of germination and as you can see germination was outstanding.

Thank you for the information.

I think my house is often colder than your greenhouse ... I heat with wood and altho' my fireplace insert is efficient, I often don't get up to feed my night fire, so the house gets quite cold at night.

Smiles,
Lyn

Some plant seedlings do like cooler nightime temperatures----as long as it does not freeze.
I do not know whether Heuchera seedlings like cool nights.
You may have to time your seed starts to the requirements of the plants.

Thank you.

Smiles,
Lyn

@Badcat. Try this again.

Yes I looked at these too!

Ok, I may try this again this year.

You want too!!! haha Im excited about the new ones I just picked up from the nurseries that were bloomed out ... they will be a surprise!

This is my first attempt at growing. Heuchera from seeds. This one is melting fire.

Those look healthy and happy. Keep us posted as they mature.