I have about 50 blackberry plants. The only ones that are doing MARGINALLY well are my thorned varieties. They are now on their third spring (planted Feb 2011). They are spindly, scrawny, and I have collected probably about 6 berries off of them total...all 50 plants combined.

I know the varieties are OK, because I gave my buddy half and he collected 5 gallons of berries. His are covered in weeds, uncared for...planted and forgotten as far as maintenance goes.

THe difference is his is planted in a sandy soil, and mine are in a heavy, thick, red clay.
I have fertilized as per TAMU recomendations. Ive tried to keep weeds down as best as I can.

What should I do to fix this? Im somewhat considering chopping them off at the ground in the fall, and then tilling in about 6" of compost on them. I don't know if this will kill them though. Pretty much starting over with ammended soil. That or just dumping compost on top and letting them re-root a bit higher up.

Im open to ideas because Im out of them. Seriously...its a f-ing weed...and its not doing that great.

You won't kill them, I promise. Till in compost & loam.

Cut them to the ground or just till as close as possible and then dump the rest on top?

If the world had nuclear war, blackberries would survive.

I'd cut them back and till it all. They'll probably go gang busters afterwards.

This should probably be done in the fall or winter?

Ideally in winter when they are dormant.

Thinking jan or feb when I normally would have planted.

So amusing. I lived in Seattle about 10 years. There are a BUNCH of businesses up in that part of the world who do nothing but blackberry removal. You can't kill them. They take over everything.

My natives do that.

What part of the state are you in? I'm guessing you've got them in decent soil?

Drainage is your issue. You're likely going to need to raise the beds or supply trench draining if you want them to thrive.

As mentioned above, it's all about drainage with the blackberries. It should be fine that they are in clay-ish stuff, but make sure they are in a raised planter or are otherwise drained well. I'd cut them back a bit for the spring, put them in a raised planter, and they should do better.

That being said, I'd be impressed if you could actually kill blackberries!

The soil seems to drain ok. It's not like it puddles. Is that what thy mean? I got an inch of rain two nights ago and today the ground is wet but not mushy. If I just dumped dirt on them and raised them, would that count or do I have to dig them up?

Do you know what your soil pH is? Blackberries can be kind of sensitive to soil pH. In alkaline soils, they seem to have difficulty taking in nutrients from the soil. In soils that are too acidic, they will overload themselves, but it takes soil with a fairly low pH to cause them problems.

Soil pH is very likely in the 8.0 region. That's part of the reason I was thinking of adding compost. My garden has been heavily composted and fertilized to get it just at or below this number. Plants there do well, but these BB are planted in a native area. I have NOT had a soil test, but for this area, that's what the pH generally is based on soil surveys.

What varieties? Does your buddy live nearby? Do they get enough sunlight? Does the soil stand water? Are you around College Station?

Waller County. My Buddy lives 20 minutes from me, totally different soil. They get plenty of light and water. I emailed TAMU about them and sent pictures and one of the guys there said he's let them go and see how they do and that they look OK. I did fertilize them with a slug of nitrogen. I have to get the weeds knocked down a bit. Ill let them go this year and if they dont do well, ill cut them down and compost heavily and see how that does since its too late to do that kind of thing now. Im also going to try to 'tip' them better. Last year, I just let them go just to get some green on them.

[This message has been edited by BrazosDog02 (edited 3/21/2013 1:57p).]