If those are orchid cacti or holiday cacti in your pictures and your temperature drops below 50 degrees Fahrenheit, they probably won't grow in your climate. Orchid cactus, holiday cacti, etc. (aka epiphylliums) are all tropical cacti and although they can take significantly more water than many cacti and succulents, they don't like to get cold and wet. If I were you, I'd put them in hanging baskets in dappled shade, and then bring them indoors for the winter.

If you would really like to grow cacti in the ground outdoors, there are plenty of varieties of cold-hardy cacti and succulents. I live in Pittsburgh, PA, which is fairly cold and wet, and I have seen plenty of people growing various varieties of Opuntia (prickly pear) in their yards. You might also look into some of the Echinocereus species, although some are cold hardy I am not sure how they'd handle the wet.

Many people on this forum also grow their cacti and succulents outdoors in the warmer seasons, then move them into the house in colder weather. This offers quite a bit more flexibility in choice of plant, but you'll be limited by your window space unless you want to install grow lights in the house =)

If not just cacti, but other succulents also interest you, there are several semperviviums (hens and chicks), sedums, agaves, and yuccas that grow quite well in cold climates that get significant rain.

I know that soil mixture isn't AS important to outdoor growers as it is to us container gardeners (maybe someone else will chime in about appropriate soil amendments), but I would want to put the plants in the sunniest, best-draining spot on my property. They probably wouldn't be happy in a shady bog.

This post was edited by kataclysm on Sun, Sep 8, 13 at 8:33

Even here in Texas with a rainfall average of 34" ( 11"-34 with a curve bustin very ocassional 50") we create raised berms of soil that have had gravel and sand added to the soil in a 1-1-1 ratio. I grow echinocactus, coryphanthas,Trichocerious and LOTs of opuntias outside. There are some other families that have cold hardy members , but I haven't got around to them yet. I protect marginal ones with blankets and Styrofoam cups overturned leaf stuffed plant pots, bubblewrap when we have cold fronts.. I have seen photos of people in the midwest cover their xeric berm with a hoop house and plastic and then heat using electric bulbs and heaters. There's get covered in snow. We are not that wet in winter, but sometimes it gets bad. It is all knowing aboutthe type of cactus. The E. grusoni was scared and half killed, The Trichcerious made it through mostly intact. This was a three day freezing rain and ice storm. What a mess.

I bring my epi in at about 40F. My Epi oxipetalum is much more cold hardy. It stays out till 32. It often gets bagged with frost cover and shoved under a porch up against the house , but then it is brought in and installed high up in the wood shop.

Its possible, but it takes thought , a plan and effort.

Below is me before my plan.Well, actually, the first photo is some wild Opuntia in the front field.

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You could always create a raised bed, and maybe a plywood cover over them. - depending on species, some need more sun than others.
I have lots of opuntias in pots, and its a real pain keeping them dry.

The weather in New Orleans is...
rain, sun, rain, sun... then its afternoon :)

The other day i poured down for 15 mins, then the sun was out again. Its killing my dragonfruit, i cant bring it in fast enough sometimes

I am afraid that without sun , more air , severe soil amendment and mounding up, those little cactus are not long for life. The epis will be happier in a hanging pot like grrenman62 said. They grow in trees and kinda like having their roots crowded . AND they just LOVE TO HANG over a pot edge and further. I have seen a huge more xeric epi relative cover whole cliffs when they are not in trees.

This is one persons idea of how to plant a dry garden below. I know people that take there native soil and add the gravel and coarse builders sand to it and pile it over the construction trash. You want a mound. But the illustration below will give you an idea. I put cardboard down before ai start my mounding to keep some of the weeds from coming up through it. Other people say to poison it or strip the topsoil out before the mounding.

Here is a link that might be useful: How to plant a dry garden