I am going to mix up a batch of potting mix, I have clay pebbles, perlite, and promix. Please help with the recipe, what % of each. Is one recipe good for most succulents and cacti or are there individual preferences to take into account?

I've never heard of Pro-Mix but found this:

http://www.greenhousemegastore...

I don't think its a good idea for succulents because of the water-saving gel. Succulent roots need a dry spell between waterings. This stuff is designed to hold moisture. That's why they say it would be great for hanging baskets.

Also, 9 months worth of fertilizer? I fertilize with 1/4 strength fertilizer maybe twice a year.

There is a high-porosity Pro-Mix (called Pro-Mix HP) which would probably be ideal for succulents.

http://www.pthorticulture.com/...

I would think you could make some useful soil out of the Pro-Mix you have plus an equal volume of perlite. As always with perlite, be careful of the dust and wear a mask... nasty stuff to get in your lungs.

What size are the clay pebbles?

Baja_Costero said:
What size are the clay pebbles?

They are called GrowIt pebbles and they are about the same size as hydroton but are not uniform.

Probably better saved for hydroponics instead of mixed into your potting soil, then.

OK thanks

And for what it's worth, quite a few succulents and cacti can be grown hydroponically, should you care to try that out at some point. There are some advantages. It's probably not the right place to start though unless you're already doing it with other plants.

I have found ProMix BX to be a great media for starting succulents.
the mycorrhizae improves the generation of roots from cuttings.
It wets easily and drys out quick enough to avoid rot at this tender stage.
I do not use it for anything larger than a 2 inch pot.

Baja_Costero said:Probably better saved for hydroponics instead of mixed into your potting soil, then.

Will use them for the orchids. That is not really hydroponics (is it?) I have read that some people use inorganic substrate for some of their orchids.

Hydroponics is a pretty wide umbrella term applying to various substrates, organic and inorganic (or none). You could even apply the term by extension to a lot of the succulents I grow... the compost in my soil breaks down to dust in a year or two, leaving my long-lived plants in a mix of pumice and cocofiber. Which works perfectly well given the regular application of low level nutrients.

In my experience, cacti and succulents rarely need repotting and are usually best left undisturbed in their original nursery pots and soil. I know folks love the process of repotting, including making their own potting mixes. But I also know from experience that folks often repot unnecessarily and end up doing more harm than good, especially if they are inexperinced.