Wondering if one of the soils I already have is suitable for a potted mini rose. I have Fafard Indoor soil and Promix Herb and Vegetable. I also have additives like worm castings and perlite.

The Fafard is:

"Sphagnum peat moss, black earth (humus), perlite, coconut husk fibre, sand, dolomitic limestone, natural fertilizer

GUARANTEED MININUM ANALYSIS
Total Nitrogen (N) - 0.35%
Available Phosphoric Acid (P2O5) - 0.20%
Soluble Potash (K2O) - 0.15%
Minimum Organic Matter - 25%
Maximum Moisture - 55%"

The Promix is:

"Canadian sphagnum peat moss (60-75%)
Peat humus (except 2 cu ft comp.)
Compost  (except 2 cu ft comp.)
Perlite
Gypsum
Limestone (for pH adjustment)
Organic fertilizer
Mycorrhizae - PTB297 Technology
Coir / coconut fibre (2 cu ft comp. only)"

The above copied and pasted from their websites.
Would either potentially work? Or should I look for something else? Or mix something?

Thanks.

From decades of experience, a mini, like almost any other rose, will grow in nearly any type of potting soil and even plain old outdoor dirt (in the ground). What they don't like is to be grown indoors, nor in too-small pots where they are exposed to too-hot direct sun where the small pot over heats and cooks the roots. I grow them in two, three and five gallon nursery cans outdoors. When I lived in the Los Angeles area in the hot, inland valley, I'd have to shield the cans from direct sun exposure to prevent that heat from damaging the roots of the rose and cooking all the moisture from the pot.

They also love the same fertilizers "regular" roses like, only in smaller doses as they are smaller plants. Because I grow mine where our dogs rule, I can't use organic types because anything "organic" is "dog food". They LOVE bone meal, feather meal, blood meal, etc. so I stick to the water soluble inorganic types so they aren't attracted to eat what I apply. Just follow the instructions on the package and make sure whatever you fertilize is well watered at least several hours prior to fertilizing so you don't burn them with the fertilizer.

I might try the Fafard. It feels like it'd be a bit better draining than the Promix. I read they need decent drainage. Or I suppose I could mix them.

Any recommendation for fertilizer? I've never grown a regular rose so I'm not sure what they like. I have a wide variety of fertilizers though, so I imagine one of them should be suitable either as is or diluted. I have a balanced Miracle Gro, an orchid fertilizer, a granular fertilizer marketed as for tomatoes, a cactus/succulent fertilizer (which is quite weak), etc.

When Ralph Moore, known as the "father of miniature roses", was asked this same question over the 70 years his nursery was open, his answer was to use a well balanced fertilizer. It doesn't matter what kind of plant the package says the fertilizer is designed for since roses can't read.

Smiles,
Lyn

I'll use the balanced Miracle Gro then.

How often should I fertilize?

Follow the package label instructions. Traditionally, they've usually stated a tablespoon of product per gallon of water applied every two weeks. But, whatever the label says, do that. They made the product, they've tested it and determined their instructions will provide the benefits desired.

When using the Fafard mix, make sure the mix in the pot is wet before planting your rose. Fafard soils are famous for being a DRY, light weight soil. Getting it wet the first time can be tricky but once wet it is a great mix for growing mini roses.

Okay, I'll do that. I have noticed that with the Fafard too. I use two of their mixes as the base of my mixtures for most of my plants, and it generally seems to work well. It does get dry and crumbly if left too long though. I noticed it got dry and fluffy in the bag, so I'll lightly soak some of it first.

Better than the Alltreat Farms soil I have somewhere. I find that stuff never dries.