I am in the same boat. I live in st louis and the weather can get extreme in either direction. Winters can be very cold and summers very hot. I have done research on this topic before and I have heard of some Agave and echinopsis that can survive the fridged temps here. Of course to increase the survival rate a bed with a drainage basin is needed. Larger, more mature plants have a greater chance of surviving but I would still recommend covering them in a clear plastic to try to trap in some warmth and protect from rain and frost.

Another thing to consider, may be a lot of work, making holes in a bed large enough to set them in durring the spring summer and fall.( you could slip a plastic bucket in to the hole like the pots you can get roses, shrubs in.) Just up to where the lip on a terracota pot would be. They will be able to stay out longer this way too because the pot and the roots inside will stay cooler durring the summer and warmer durring autumn.

There is another thread posted not too long ago titled "cold hardy" or "cold hardy cactus" something along those lines. A poster put up the name of a book that has helped him raise cactus in Canada.

Hope this has helped :)
plant_junkie

I found that book suggested by another poster: 'Cactus in the Snow' by Bruce Brethauer - it's subtitled 'A Guide to Growing Hardy Cacti in the Wet and Frozen North'
plant_junkie

Drat, Amazon doesn't have it. I will continue to look. Thank you much for the advice plant junkie.

Its great having unusual plants growing in my yard. Stuff unusual enough even my apartment living friends ask about it. Think these cacti are the next step.

Marc, I have been looking for you, try Delosperma kofleri x D. nubigenum , Carnegiea gigantea with a broad thick stem, thick stem do better than thin stems, just like my San. stuckii will tolerate the cold better than, than flat stems and soft tip species. Cactus with thick old skins 'Old Man of the Andes' thick hair will also do better,
dried plants with less water in them also do better, so gradually dry them out starting now and give water less often starting now. Never water if your are expecting rain. When the forcast no rain to 10 days then you water, watch the temperaures at night, cover with plastic or build up 2 construction blocks, on each end and cover with plastic, and hold down with construction blocks on top at the ends as well, or or use a old piece of glass. I use discarded sliding glass doors. or you lean these doors up against your house, or wall. put the plants underneath, seal the openings with 8 ml plastic to keep warm and dry. My Shick hybrids got through 20 F for five nights, they survived but didn't flower this past year. Call the Missouri Gardens and ask them to make suggestions on what to grow or go to the Garden and look and see what they are growing out side. Norma

Probably a good choice. I'm due to take a fall trip to MoBot soon. Maybe if I go on a weekday there will be more employees wandering about.

Just typed a big reply and the system rejected the message ... Grrrrrrr.

The short form:

Carnegiea gigantea only listed as hardy to 28 degree F.

3 books:
"Growing Winter Hardy Cacti" by John Spain (available from
MesaGardens)
"Cactus in the Snow" by Bruce Brethauer (available from
MesaGardens)
"Hardy Succulents" by Gwen Moore Kelaidis (available from
Amazon)

Nurseries (all mail order):

ColdHardyCactus as you noted. Good source of hybrid
Opuntia.

MesaGardens - Good source of seeds and small plants
(concentraion on the species and variations
within species)

HighCountryGardens - Good source of xeric plants. Have
more cacti and succulents on their website than
in catalog.

SquawMountainGardens - sood source for Sedum and
sempervivums

ForestFarm - can be considered a source for some items.
High shipping to east coast.

I should also note that I know of a forum for strictly cold-hardy/outdoor cacti growing. If you're interested, contact me directly.

I too am interested in Cactus that will make it thru our cold wet winters here is eastern KY. I have a prickly pear,large spines, no name variety that thrives, but never bloomed. I also have a smaller padded cactus with no spines that bloomed yellow in early summer. both are planted, not in pots. Like the idea of using a glass or plastic against the house to protect during winter for those marginally hardly cacti in pots.