" I just bought a 60 lb bale of Promix BX but I've never used it in containers for annuals. Any advice on what to add to it, if anything? "

Are you talking about growing your annuals just in the containers for their entire life? If so, you might be concerned about water retention. You could add some horticultural Perlite to reduce water retention. I am not familiar with Dynamite CRF, so can't comment on that.

ProMix BX does contain added limestone, but only to supply seedlings enough Calcium until they are set in-ground. As a permanent container mix, the ProMix BX calcium content may be depleted, so you may want to consider remedying that. I include Calcium nitrate in my soluble nutrients.

Culturing plants indefinitely in a sterile growing medium is essentially a form of hydroponics, in which the medium acts only as a supporting substrate. Hydroponics growers almost always add Calcium nitrate to their hydroponic water, along with a complete soluble nutrient formula.

Calcium nitrate is available at almost any hydroponics supplier, and is relatively inexpensive. It is very soluble in water and you don't want to leave it in the open because it is hygroscopic and will dissolve itself in water from the atmosphere. So keep it in a closed container.

ZM

The product already contains perlite and vermiculite and apparently calcium and magnesium:

http://www.pthorticulture.com/en/products/pro-mix-bx-mycorrhizae/#tab:product-specification

It's a good potting medium and I've used it a time or two. I'm presently using something I like better, but I'd buy it again, if I couldn't get my brand.

how big are the pots.. and the real question is... is the rule the same for each???

i found when you get past 5 gals or so ... that mixing in about 50% mini bark nuggets... really helps ...

a giant gob of promix... can settle over the season ...

use the search bar for al's gritty mix.. if you want to learn about media ... making your own.. and how to use it

ken

I've made Al's 5-1-1 and I use it in my 20 gallon geopot containers for growing tomatoes. The ProMix BX I am asking about is strictly going to be used in my small containers for my annual flowers. I'm just asking if using the mix straight of the bag is fine or if I should add anything to it like a CRF?

Of course, you'll need to add a fertilizer of some kind, CRF or otherwise. Most people would be very satisfied with this brand's performance for a growing season, as long as proper watering techniques are adhered to and fertilizer is added.

That's exactly what I needed to know. Thanks! I'll probably use Osmocote Plus because I can find it locally as opposed to Dynamite which I have to order online.

I've used Osmocote Plus and like it.

i was just reminded.. in another post.. that there is a container forum ... and you might learn all kinds of things there ...

be very careful with time release ... it needs to go on early ... and be washing out.. later in the season ... if you plan on wintering over stuff in pots ... i think your name refers to NJ??? .. but i dont know the zone???

of course.. if its only annuals ... feed away ...

ken

duh.. its the annuals forum .. lol .. mock self ...

ken

I use pro mix BX in my greenhouse for starting plants and in pots. Pro mix is mostly peat moss with a lot of perlite and vermiculite. It also has a good fungus that promotes root growth. Pro mix BX is made for hanging pots or any pots for that matter. If you want a faster draining mix use pro mix HP. However I do not find that the BX holds too much moisture. I've had zonal and ivy geraniums in it all summer and they thrived but then I don't water every day either

Pro mix potting soil contains slow release fertilizer and everything needed for growing in pots. It contains Canadian sphagnum peat moss, coconut fibre (coir), perlite, limestone, slow release fertilzer and mycorrhizae. Mycorrhisae is a good fungus that promotes root growth