Is anyone growing these plants and if so, can you share your observations? I purchased 35 plug plants, put them in the ground in February and they seem to be doing ridiculously well (for me anyway).

where did you buy them?

Nourse Farms.

Earl! I'm thinking the Prime Ark blackberries were developed by the University of Arkansas, and they are supposed to produce berries the first year. They look great to me, do you have plans to trellis them? Oops, I just saw the wires in the pic.
Most of the U of A developments are bred to grow in a variety of climactic conditions.

Hi Lynda,
Yep, thornless primocanes from UoA. They are so danged new that there isn't a lot of experience with this variety on the net. I was completely surprised by how fast they grew from itty-biddy 2" plugs that had about 3"of above ground vegetation to about 40" just 3 months later. It begs questions about tipping and irrigation methods to sustain this growth that I just can't find particular to this variety.

I would suggest going to the Uof A website, it's uada.edu. There might be some information there.

I'm kind of like a new parent that has read all of the literature, follows all the advice then freaks out when the kid gets an upset stomach! For instance, these plants are putting on berries now, more than I expected for such a young plant. Is that normal for a primocane fruiting plant to set fruit in May, or is it gonna be like my peach trees that bloom in November even though they require 400 chill hours? How is the first year different than subsequent years? Is my irrigation system, adapted from my muscadine plan ok for blackberries?
Just a nervous parent looking for a seasoned grandmother for advice😁.

I think it's normal for these to produce the first year. If what I remember the U of A said about this variety, it may produce a smaller crop in the fall. Of course, blackberries don't take near as long to produce as peach trees!
If you wanted a different variety, U of A has developed a lot, all the names are indigenous tribal names, like Ouachita., Navaho, etc.

I started a trial patch 4 years ago using locally procured Navaho and Natchez - 3 plants each. They have not done well, but I learned a lot from the issues I had. First, they hated mushroom compost that I bought a lot of. I've sense read that it can contain a lot of salt. Second, as much as I love using mulch, it seemed to promote ants and contribute to roots spreading above the soil and below the mulch which get damaged when it gets cold. Third, do not use cedar mulch! Fourth, landscape cloth allowed Bermuda grass runners to form a thick mat under the cloth. Fifth, North Florida soil is about 90% sand and holds no nitrogen; you have to fertilize everything!
So for the Freedoms I used my own compost, no mulch, no landscape cloth, a little lime, a little 10-10-10 and a drip irrigation system. I have also retired since the trial patch and have a lot more time to care for them. I have made about 10 yards of compost the last couple of years so I may use that as a mulch later in the year.

Our canes at the MG project arent mulched. Sounds like you had a time with your first plants! I'm careful about what I use for mulch for anything I'm going to eat, it needs to be neutral. So I usually use straw or Timothy hay for veggies and herbs like basil. The cedar/cypress mulch I save for the perennial flower beds. Now folks around here do mulch their blueberries with pine needles, they like acid. A lot of berries seem to like pine needles for mulch. There is a local u pick farm that grows blackberries, strawberries and blueberries, and the lady that owns it will come and buy pine needles from folks if it's clean and not full of trash.

With all the concerns with the Prim-Ark Freedom's, it was all for naught. The plants grew and grew, grew then grew some more, Some canes were in the neighborhood of 16' long! With 35 plants, I got about 60#'s of berries over the summer and fall, with all berries forming on the tips of the canes.

Now that spring has sprung, I'm seeing flower buds, flowers and green fruit all up and down the canes except where last years Primocane fruit was, that part is now dead. I had the occasion of speaking to Dr. John Clark from the University of Arkansas who felt I might just have a huge spring florocane crop based on a light (in his opinion) Primocane crop.

So far this has been a success story!