Growing Cacti in the Garden

Hello I'm new I've spent about two days going through the forum and the information is awesome.

I've noticed most people keep their collection in pots. I started collecting on a small scale about ten years ago, and then gave it up for a few when we were renting and had no space, all the pots were at Mum and Dad's, most of them have survived fine expect for a couple of root-bound ones which I am nursing at the moment. We're building a house and I have an absolutely enormous area to plant all the cacti. It does get a lot of sun, it's the back corner so it is relatively protected from wind as it has the three fencelines and the back wall of the house, there's also a huge gum on one side which shades one part.
Anyway I have been wanting to do this for years and I have a while to plan it, and some great established cacti and succulents to go in (and in a sudden new collecting frenzy am gathering a lot more). Any advice? Soil I know will be a problem but I have plenty of time to work on the soil before I plant. I was a fairly small-scale collector before so I have not had a lot of problems with sun exposure or pests etc and not a lot of experience in that.
And thank you in advance!

Welcome to the forum Olga. Can't help with the soil, mine are all in pots except for a few succulents that I shoved in the garden and they went berserk, probably coz I am on a sloping block. Will let the experts here give you advice, good luck with the project.

Thanks Vicki I have actually discovered a couple of threads since which have given me ideas for the soil.
I think I'm a bit concerned about what sort of pests I may encounter in garden planting, so far I have never had any major pest problems in pots.

G'day Olga...

I'm in similar circumstances to you at the moment, and I'm in the process of planning a cactus and succulent garden bed. I'm planning on including mostly succulents, but with a mixture of Trichocereus, Echinopsis, Opuntia and Cereus as accent plants. All are pretty outdoor-hardy, however I reckon drainage could be an issue. What I'm looking at doing is building a raised garden bed, and including a lot of free-draining material in the mix to avoid water pooling and causing root rot.

One thing that I find helpful is looking around the suburbs to see what species people already have established in their gardens in your area. Generally, if you can look at older, established gardens you will see what survives in our climate the best. The usual suspects like various Opuntias, Trich spach, the ubiquitous Cereus peruvianus, etc seem pretty cold- and damp-tolerant, which to my mind makes them ideal for outdoor plantings. They also all have really nice structure to them, which coupled with the right succulents should make for a very effective planting.

Thanks Lachy I live in Bayside too, we're actually moving down to a new area (Lyndhurst) and everyone has those minimal native gardens *sigh*
I have also rarely seen any cactus in this area besides giant ancient prickly pears...we get no frost in Dingley, so I figure there is none there, we're only about 20 minutes from where we're moving.
I am collecting some Cereus at the moment, I have a few old barrels (I have yet to identify but these have been planted here for ages and been fine) and Mamms, I see Cactuspolecat has those in Tassie with little issue. I have actually bought a lot of Euphorbias online, my old giant clumping one is still hardy ten years on so I am hoping I can plant a lot of those, the patterns are awesome.
Yes I was thinking a raised one with a couple of levels, it should be expensive for rocks and stuff so well do it slowly, but I am the sort who likes to plan months ahead