Much longer acclimatization in a controlled humid environment is necessary before planting out. Progressively increasing the ventilation over a period of weeks or months is the only way to gently harden-off your delicate moisture-dependent sporelings. They don't stand much chance otherwise.

Check out the propagation sections in a couple of good fern books - plus a website or two - and tinker around with your propagation set-up.

Thank you, I will do as you advise - guess I'll have window sills full of little ferns for a while - its worth it, such satisfaction having them actually growing.

Yes, just try and stretch out the hardening-off process a little more. Maybe commission another propagator box or two solely for this bit, and so not mix up the more advanced specimens with the more fragile ones. Gradually increase the ventilation each week. Prop the lid right open for the final few weeks and only then try your youngsters outside. Don't worry too much if headroom gets cramped - squashed hardened-off plants are better than sappy fragile things.

Certainly there are species that more readily adapt to the rigours of life outside a protected propagator box, but I'd still struggle to get anything to survive if I didn't have a little production line of humid micro-environments - each more ventilated than the previous set-up - to pass my developing ferns through. A glasshouse with some kind of auto-control over the misting makes things a great deal easier too.

Steve - Brighton, UK

Steve - I have the good fortune of a few woodland areas where tiny sword ferns and lady ferns are coming up- I call them my fern nurseries. Since they naturally handle the outdoors (I know, they started their lives there so they're more acclimated), I thought my indoor babies would go outdoors more easily. I truly appreciate what mother nature decided to do on her own, hundreds of babies that I can move around as they get large enough to survive a move. I figured if they could propagate themselves, how hard could it be for me to do? Well, not that easy but I'm happy with my success and will do my best to keep them alive and growing.

Yes, you'll notice that your existing 'outdoor' ferns accept less mollycoddling in the propagation process than more exotic varieties. Even so, it's not really possible to move stock from a sealed propagator box straight to an outdoor environment without acclimatisation. Anything raised in a sealed 100 per cent humidity environment will need a gradual toughening-up regime - weeks or months - before it's safe to expose it to the rigours of outdoor life.

Steve - Brighton, Sussex Coast, UK

I had luck putting my container of babies into a large plastic bag and then I could control the humidity by opening or closing the bag. Just take it slow. Nancy

this post is rather old so i hope i get some response!! I have some boston ferns that i just love!! i am interested in propogating them.......i am told that many ferns purchased from retailers are sterile.......and can not reproduce..........is this true?? if not......mine do not develop spores.........so do i propogate by some other method???? vicki

Easy day. Just knock your clump of boston fern out of the pot, take a sharp knife and carve it in half or in quarters, then pot them up.