Just and adendum to my last message. The Supersoil mix is actually called Supersoil Palm & Cactus Mix. The ingredients are:
Aged & processed softwood bark & sawdust
Sphagnum peat moss
Pumice
Sand
Compost

MG Organic Choice Potting Mix contains:
50-55% composted bark
Sphagnun peat moss
Pasteurized poultry litter
Organic wetting agent (whatever that is lol)

Just thought a little more information might be helpful.

(Really wish there was a feature here where you could edit a post, rather than having to post another message.)

As long as the mix holds some water, it will probably work just fine for your minis. Eucalyptus bark is supposedly a decent mulch but I wouldn't put it in the container except as a drainage layer at the bottom.

I did a little experiment with my mix in a 5 1/2" diameter and 5 " high plastic pot. It held water for about 1 1/2 days. So maybe it needs a little vermiculite? About some fir bark?

Thanks for your input moroseaz. Hope your day is going well.

lol Meant to say "How about some fir bark?" Guess I'm not quite awake yet!

Still, bark only as mulch or drainage layer at bottom. Large particulates need nitrogen to continue breaking down and they'll take that nitrogen from the plant.

I'm guessing there's too much peat moss in your mix. Try adding the vermiculite, cheap potting soil or a little clay from the yard. Once the peat moss gets boggy-like, it won't release the water very quickly and you may end up with root rot. Adding some clay in there and mixing it thoroughly adds weight to the soil and breaks up the peat moss so it doesn't matte.

I have approximately 100 roses growing in containers mostly in the 10 - 12" size for minis. Some of the minifloras and more vigorous minis will likely need to be moved up to 14" containers next year. I combine regular Miracle Gro potting mix and the Supersoil Palm and Cactus mix at about a 60% to 40% ratio. I also add some perlite and pumice to the mix. I fertilize with Osmocote. I don't put anything in the bottom of the pots for drainage nor do add any much on top. This has worked well for me for several years. Summers are much cooler down here in the higher elevations of Cochise County than you guys up in Phoenix and Tucson so I guess I can get by without the mulching.

dave

I prefferance a sharper draining composition and to avoid perching water in contianers at a 1 1 1 ratio I use aged fir pinefines, perlite, and composted gravel which sometimes becomes silca sand or just sifted sand (sifted to size #5-#10 for all three)a 10% of humice is sometimes used as well.

The mix and sized out sifts varies a little with 1)container size 2) will I be over wintering them inside or out side.... Ect. The goal is to have a VERY close to free draining but moisture retaining container with NO WATER perching.

You have a list of soil compostions with a few items I would not use even if they paid me to use them. As a certainty sluge peats and vermi hold to much water (way to much for a continer IMO). Maybe I'm older sence roses have been growing in continers for a while (SEVERAL YEARS) with out the use of a MG's or any other wetting agent, with that in mind I don't see any real need/bennifits with the use this item either.

Other REAL good continer soil composition items are mentioned as pumice, any items this pourus are ideal but add a screen ( not a shard from a broken pot) to prevent ANY items from falling out of the bottom hole(s)of the container.
I use several terra cotta, some deco ceramics & bonsia type continers when hotter, sunnier days will require wraping and tie the exterior of some types of containers with wet towels or a cloth of this type and/or move from direct sun to a more shade protected area. A small perk is with the mix(s) I use a terra cotta pulls MOISTURE in from the towel while it dries.