It's about the particle size where drainage is concerned. The pieces of bark should be roughly the same size as the pieces of perlite.

The composted stuff isn't bad to use, it will hold more water and less air, but works fine for veggies and 'pretty flowery stuff' (annuals).

If you want the fast draining though you want the bark and perlite to be comparable in size. I believe Al has posted some pics of the bark in his water movement threads for comparison.

Yes, I've seen the pictures. That's why I was questioning what I've mixed here. I am going to do a tomato container or two, and I have many other smaller potted plants. But what I mainly want this for is a rubber plant, a real nice red one, that I just spent some money on, (even on sale). I'm not sure now if I should pot my rubber plant in this mix. I also have a 'Sunshine' blueberry that isn't very happy with me right now, and I thought it might like something new. :)

Hmmm... Well, even if all the bark is well composted I would still use it for tomatos. The extra water retention will do them good and the lower air retention is something they are quite tolerant of (to a point, of course).

I haven't grown a rubber plant so can't/won't comment there, but the blueberry should do fine, at least for this year with the mix you have. You say it isn't very happy with you right now, but I would need to know more about what the plant is doing to try and help find a solution. Blueberries can be tricky in the ground or containers, but they are certainly do-able, they just require a slight shift in their care from many other plants.

Well, the blueberry is rather a long story. I bought a $10 mail order plant, it was delivered to my door last April in the middle of the Easter freeze we had here. I was out of town, came home to find box on doorstep with what looked like frozen/dead plant inside. So the company very nicely replaced the plant. I had watered the 'dead' one and sat it in a sunny window, potted up the new plant. One day three weeks later, lo and behold, a tiny sprig of green was at the base of the 'dead' plant! So I potted it as well in with the other one. Both grew reasonably well over last summer. When I brought them in for the winter, they did fine, bloomed in February, then the replacement plant promptly died. Black stem, branches and all. I thought the original one was dead as well, lots of black, I pruned the stems,and once again, this stubborn little determined thing has just started setting out baby leaves again. I'd like to do something nice for it, and thought Al's mix might be just the ticket...

Al's mix will do nicely for your blueberry, but please do not bring it inside and try to grow it as a houseplant in the winter.

It just isn't suited for this and it will struggle and possibly die. Instead, leave it outside in a location that gets no direct sun (to avoid freeze/thaw cycles) or place it in an unheated shed/garage/whatever.

These plants need to go dormant for a period. If they do not get this dormant period they suffer and will eventually die. They require some cold to go dormant. How much cold they can take depends on their hardiness, but they all require a dormant period.

If it's in my unheated shed, do I still water it?

If it's in my unheated shed, do I still water it?

Yes, but very sparingly and using a very fast draining mix greatly simplifies things.

If temps are sub freezing in the shed then do not water as the plant can't take up ice :-)

When temps are above freezing some moisture is good, but this is one point where the potting mix changes from 'a lot of mixes work' (during summer) to the point where the mix can mean the difference between life and death.

Watering during the winter, dormant period means the plant needs some water, but any excess will just result in rot/damage. As a result you will want to water completely when you do water, but you (your shrubs) need a mix that will hold on to sufficient water while never being waterlogged.

You can only achieve this with a fast draining mix and this means a mix comprised of larger particles than peat/compost/dirt so there is rapid and complete drainage.

If I may ask, where do you live? Specifically I am wondering what your winter temps and humidity are like. In Wisconsin where I live I can put a dormant plant into the shed and 6 months later when spring arrives the potting mix still has ample moisture. Your area may be different.

Some plants, like geraniums, I overwinter in a heated basement in front of a sunny window. These do not have the dormancy requirements a blueberry does. These I water about 2-4 times over the 6-7 months they are indoors.

Overwintering is one of the more difficult things to understand how to do correctly from reading information. You kind of just have to try it and focus on letting the potting mix be as dry as it gets during sub freezing temps and above freezing temps keep a small amount of moisture available, but not sogginess.

Again, a fast draining mix makes this a lot easier than a water retentive mix does.

When your blueberries have no leaves at all and it is dormant you should absolutely err on the side of under watering rather than over watering.

I'm just outside of Kansas City, in Independence, MO. My zone is officially 6 on most of the maps and internet 'find your zone by zip code' things. It's that funny little circle of 6 right in the middle of zone 5 on the west side of the state. But that said, there was a winter here (I think '89) when we had record -23 temps for 3 days in Dec. I try to lean toward the zone 5 side with my plants, and generally have good results. I also have a 'cold' area of my basement where there is no heat, and a pretty good size yard, with south exposure.
Humidity is good in the summer, not as much as Tennessee, which is my original home state, and fair in the winter. So it's the midwest - fickle stuff, weather.

Yeah, i understand the midwest weather as I live in Wisconsin which is also zone 5 (some years flirts with zone 6 and other years flirts with zone 4).

You still need to develop a feel for what your overwintering plants require in terms of water, but I will also say 'when in doubt, do not water'.

As noted, even those plants I over winter in a heated basement with lots of light I only water very infrequently and those plants overwintering in a sunless existence I do not water at all. This is in zone 5 Wisconsin and your climate can pose significant differences. It would be nice if there were some rule we could all follow, but there isn't .(that I know of) It requires a certain 'feel' for which there is no shortcut to experience other than to say err on the side of underwatering with dormant plants.

Well thanks, jag. I'll repot my determined little blue, and then this fall bring it into the shed. It's dark in there, but lots of times the kids will leave the door open for one thing or another. Some light gets in, but it's very protected anyway.
Now I just need to find someone who knows as much about rubber plants as you do about blueberries! :)