I have problems with squirrels digging and pulling plants out, window sills are the only safe place.
Eastern exposures killing roots through rapid freeze thaw...I never considered that. My 15 sq ft of garden is precious, there's not much room for failure.
ClifflineGardens dot com
Fort Collins, CO zone 5b
Here's my update, as of 10.18.2013
Survivors - Acantholimon armenum, Arabis x kellereri, Campanula betulifolia, Daphne 'Lawrence Crocker', Penstemon uintahensis
Species which were propagated this summer and proved to survive the Chicago 4th floor in 90% equal parts sand, diatomite, perlite and 10% peat;
Aquilegia caerulea, Aquilegia jonesii, Aquilegia canadensis, Penstemon digitalis, P. hirsutus, P. grandiflorus, Helianthus occidentalis, Houstonia longifolia, Delosperma nubigenum, Sempervivums, Solidago sciaphila, Aster macrophyllus, Aster laevis, Koeleria glauca, Eragrostis spectabilis, Opuntia humifusa, Sedums (duh), Petrorhagia saxifraga, Phemeranthus calycinus, Phemeranthus rugospermum, Viola palmata, Allium sikkimense, Viola adunca, Silene regia, Antennaria neglecta, Scutellaria leonardii, Arenaria stricta
It is of note, that on the 4th floor, it seems that everything becomes rather choice, and small. All species of Aquilegia are the same size. Jonesii is quite small, conversely, A. canadensis can be three feet. On my sills, they're maybe 4 inches tall.
Thanks for the useful information, GreenRoofer. I've never seen Phemeranthus rugospermum before. It is just as nice (or nicer) as the Phemeranthus parviflorus in western Minnesota. The two species are nearly identical, botanically speaking. I hope you didn't let the seeds drop to the sidewalk below!
Rick Rodich zone 4a. Annual precipitation ~24 inches
near Minneapolis, Minnesota, USA
Gathered all I could, I am hoping that the seeds crossed with the Phemeranthus calycinus to make something new. There's some overlap in their blooming times, but I'm not sure if this genus is 'promiscuous'.
I can only say that I have had two species of Phemeranthus, calycinus (to 8 inches) and an unidentified species kinda like brevifolia (to 4 inches), that hop around in my pot menagerie for at least five years. I have never observed any intermediaries.
It will be interesting to see how the plants do over winter.. Have the pots been insulated at all? I find a few plants here will survive in small pots sitting out on top of the soil, but very few. Any plants I have outside in pots are sunk into the soil for winter.. There is some point where the pot becomes large enough sitting on the soil for plants to survive, but I'm not sure where the line is...
west central alberta, canada; just under 1000m; record temps:min -45C/-49F;max 34C/93F; http://picasaweb.google.ca/cactuscactus http://urbanehillbillycanada.blogspot.com/
ill put them in the shade, in a group most likely. my porch should accomplish that quite nicely. I think they'll survive...we'll see.
Grouped should help give them some soil mass to keep temps more consistent. I'd probably try to insulate in some way as well, but my climate is more severe than yours- even pots sitting on the surface of the ground, under snow most of the winter, with no freeze thaw, are not safe- but of course we have the freeze/thaw in spring and fall..
Looking forward to your spring update.