Our raspberries are in the ground, not in pots. We have Heritage everbearing red raspberries. If I don't thin them, they begin to crowd each other out, and eventually they develop into an impenetrable thicket, and I am not able to pick all of the fruit. I think you will have to thin, but I'm not sure exactly how much.

Fall bearing raspberries can produce 2 crops. So the canes that produced last fall, the lower 2/3 can produce another crop. But in a pot they might smother the new primocanes.
You said you cut them down, which is probably a must in a pot. So these are primocanes and will produce in the fall. You can remove weak canes, but I would think 2 or 3 in one pot would be fine. In ground you try to keep cains 6 inches apart. Removing the weakest when closer. But I only do that for established plants when new, i let them grow closer. They look great! Raspberries rock!

Since these are in containers i have a hunch that the twice a year pruning method might be good for them.

You prune out the 2nd year canes after they fruit during the summer and then when winter comes you prune off the top sections of the new canes that fruited along with any weak canes keeping 3-4 strong canes for the next year for late spring treat

I never tried container growing raspberries, but i think the twice a year method is an option to complete pruning since the containers only have so much nutrition compared to in-ground raspberries.

i am growing them as fall only so i completely cut down the canes to the soil level. If i had to guess (which i do because i cant see with all the leaves) there are easily 10 canes growing in each pot. Wont the productivity be really limited with only 2 or 3 canes per pot (these are 16" pots i think). Erich k, for some reason i cant picture what you are suggesting. My problem is there are a ton of 1st year canes.
Thanks

I think might need to explain a bit more since i think you got the wrong idea.

The 3-4 cane pruning is after the growing season is over. This method is only if you want 2 separate crops. If you don't mind being fall only complete pruning is fine.

Normally for my in-ground raspberries i prune all but 5 canes max per bunch. This makes sure they produce a decent amount since the weaker 2nd year canes are not there taking up extra resources.

My frame of mind was since the raspberry plant put enough energy into growing all those canes i wouldn't want to squander it by letting a couple of the strongest canes to grow the late spring/early summer crop.

This post was edited by Erich_k on Sat, May 18, 13 at 21:06

Since you have two pots, perhaps some experimentation is in order? You could thin one, leave the other one as is, and compare the results. I transplanted some suckers from my in ground plants to pots earlier this year, so what you find out could be very helpful to me next year... ;)

Shazaam. I was actually going to do that since I have 2 plants of the same variety in addition to two others. The odd thing is that now some of the taller canes look like they may be getting flower buds. I definitely cut them to within an inch or two of the soil so I can't figure out why (except for the recent colder spell?).

Eric. Now I get it