Michael Bell wrote in
. uk:

I have germinated alder seeds in a Stewart thermostatted propagator,
on dishcloth soaked in water and baby bio. The seedling are now about
1.5" high and they have put their roots down through the weave of the
dishcloth. The ventilation slots were half open and the inside of the
plastic cover covered with droplets. Now I have opened the slots, the
inside has dried out. I now want to plant them out onto compost under
lighting grow them on. How slowly should I harden them to this new
dryer environment?

Michael Bell


Would a birch family seedling need to be hardened off?
Are they birch?

I am unsure, but if they are a native species throw them into their growing
space, lob a bit of soil on top and wait until spring. Honest, if as I
think they are native, don't worry.
Obviously if you want to spur them on a bit in growth, treat them to a bag
of compost. Sit back and watch them grow!

Baz