Any of the mixes suggested in this forum are fine. You can fertilize with anything you want. Coffee grounds need to breakdown, but would work eventually. A more balanced fertilizer would be better, but you can still use the grounds if you wish. Do you know how to grow them? They fruit on 2nd year canes, then you remove those canes. Are they upright, semi-upright, or trailing? Blackberries do better in the ground but can be grown in pots. Some canes can grow to 20 feet. You can cut those back some to control. You also prune to induce lateral growth, but you may want to avoid that in a pot. Depending on growth habit, they are different ways to handle them. With trailing you can wrap canes in a circle using two stakes for support.
Upright or semi-upright you just leave alone.
If you use any of the mixes suggested in other threads I would leave out any lime. You can use gypsum instead.
I would use the 5-1-1 mix, it works well for blackberries.
What cultivars (variety) did you order?

This post was edited by Drew51 on Wed, Jan 7, 15 at 17:29

I have done a good amount of research on blackberries but I have decided to try them in pots because I am not sure if I am ready for the commitment of putting them in the ground and possibly not being able to dig all of the roots up. Also, I couldn't make up my mind on the type I wanted to grow so I will try them in pots and then possibly plant my favorite variety in the ground in the future. I am trying 4 thornless varieties: Navaho, Ouchita, Apache, and Natchez. I have been having a hard time finding good information on how to grow them in pots vs ground which is why I posted here. All of the varieties are erect to semi erect.

Thank you for the suggestion on the soil mix. Let me know if you have any other suggestions.

I assume you're in zone 9. Being in 6a our conditions are way different. I grow many blackberries. I lost an apache to cold temps. I have Navaho, and Natchez.
I also have Columbia Star, Triple Crown, Chester, Loch Ness, Black Diamond, and Siskiyou.
I prefer trailing so I can protect them in the winter. I actually would like to breed a hardier blackberry. It is a project of mine, but I'm still practicing propagation techniques.
In your zone, this is not a concern.
I use some for jam, and some for fresh eating. I like Triple Crown, and Siskiyou as the best tasting. I have yet to try Columbia Star and Black Diamond. They were just added, but are supposed to be good.
Out of the ones you have I think Navaho tastes best. Natchez the worst, but it may taste better in your zone. it has huge berries and the plant is very vigorous! Taste though is not very good. Great for jam!
Here is a photo of my Natchez, taken in the fall. The one on the left, canes were 7 to 9 feet long.
Not the best photo, all I have.
{{gwi:126005}}

Leaves are around the plant because many trailing canes are on the ground from other plants. I covered them up for the winter.
I also grow many raspberry-blackberry hybrids
Boysenberry, Tayberry, Marionberry, and wyeberry.
Marion is the best of all listed in the post, Wow! Boysenberry varies by year and conditions.. Some years it is super good! Wyeberry and Tayberry have strong raspberry flavor and make the best jam. They are tart too, so best for jam.

If you want an upright the best one by far is Triple Crown. Excellent tasting large berries. Thornless too.

Raspberries are the worst for spreading but blackberries can spread too. But hardly ever do, although they can sucker!. Growth is out of the crown and spread more by tip rooting then suckers. Raspberries constantly sucker except black raspberries. Blackcaps are more like blackberries and only grow out of the crown. Propagate black raspberries and blackberries by tip rooting. I have about 21 different cultivars of raspberries also. One of my favorite fruits. I have to constantly remove suckers I don't want.

Here is a photo of some of my trailing types covered by leaves to protect. In the spring I will tie them to the trellis for easy picking. I'll let new canes trail on the ground. I also cover them with burlap, not done yet in this photo. And that's Jesse the wonder dog who keeps squirrels and birds out of my garden!
{{gwi:125957}}

Going back to what you have none are really that bad. I like Navaho a lot and Apache is good too. I don't know much about Ouchita, never grew it, but heard it is a good plant, so you did OK! If you end up want to try others Triple Crown, Marionberry, Newberry (friends tell me it's great!), and boysenberry are good choices. Only Triple Crown is thornless though. The thorns are very annoying!
They are huge and very sharp! Your choices are excellent for your zone too. Good luck, keep us updated.
If you don't want to make your own soil mix, I like Fafard, and Happy Frog. Expensive, but excellent mixes. Any of the Fafard, they make numerous mixes. Hard to find though. They have a store finder on their web site. Just put in your zip code. www.farard.com

This post was edited by Drew51 on Thu, Jan 8, 15 at 1:09