I think you have a fine idea there. Should work fine. Don't let them go dry in the pots

As someone who has plenty of ostrich ferns in zone 4, northern Minnesota, with new babies cropping up continuously - plant it or sink the pot outdoors now. This is the time of year they're starting to yellow and get ready to die back for the season, so expect that with yours. They're perfectly hardy down to -50 degrees Fahrenheit which is probably somewhere in, I don't know, zone 2? And the fastest way to do it in is to treat it as a houseplant and kill it with kindness.

Actually, I was referring to planting it in the ground rather than a pot. Ostrich is an aggressive fern and I'm thinking it will not prosper over the long haul stuffed in any size pot. It will quickly fill even a 16-20" pot w/roots. These are native ferns and will thrive in your Zone 6/7 garden. If you leave it in the pot over the winter it could become dinner for hungry voles, mice, etc. that get in the pot and eat the roots right off the poor thing and you'll have to make sure the pot doesn't dry out during thaw cycles also. There are many good ferns suitable for pot culture but, IMO, Ostrich fern isn't one of them. Again, this is due to its aggressive growth habits...this is no wimpy, delicate, 'help me or I'll perish' plant. They are awesome interplanted with Oriental lilies since the Ostrich fern can take 1/2 day of sun just fine if it has the classic "well-drained, moist but not wet" soil. The large fronds hide the rather ugly lily stems and the blooms peeking out of the ferns is lovely (smells lovely too!). I like omphalodes cappadocica 'Parisian Skies' planted at the feet of Ostrich ferns too. Anyway, don't worry about your fern...it will do fine.

After some winds and rain last night the looked worse, so I gave them a hearty cut back this morning.... Hope they still have enough tops to feed the roots! :-)