You can use just about anything. I like to prep soil with a lot of compost. I don't fertilize for 3-4 weeks when freshly transplanted, then add an organic. Once a week I hit them with a soluable at 1/4 strength. I have found that they do there own thing. Food is available if needed, and some thrive, others are slower to respond. Fertilizer may do nothing to speed growth, and if not actively growing could even burn them. Soil prep seems to make the most difference. If I don't amend the soil, they are rather slow to grow.

The first year the root system is getting established with very little top growth. Next year they will explode with top growth, especially the Triple Crown. Good luck. Bill

All of my berry plants were slow growers the year of planting. The second year they took off with many new canes emerging. Be patient, you will get much faster growth next spring. That is just my experience, there are many here with much more knowledge than I.

They can grow fast the first year, many did for me, some did not.

I am afraid to fertilize my blackberries as they are huge this year and filled with buds and 'green' berries so far. I want excellent pollination so my netting is not yet up. Mrs. G Looks like an excellent year for berries.

I'm getting yellowing of lower leaves on my raspberries, even new canes so maybe time to fertilize, or could be all the rain we've been getting. But time to fertilize is in early spring (March/April around here) and I missed it, so will have to try after harvest.

My TC blackberries planted 2012 didn't do a whole lot that year, did leaf out nicely last year and some fruit, but they really have developed a lot of fruiting laterals this year (maybe b/c I didn't prune at all in 2012, but did tip root some canes last year and cut them to separate the plants this spring).

Mrs. G - looks like a really good year for wild blackberries, blueberries and raspberries - too soon to tell with my TC. Darn squirrels driving me crazy with the strawberries though. Just wondering, how are the mtn laurel over there (wonderful scenic drive by URI)? Don't seem to have a lot of flowers here.

Here is a link that might be useful: U Maine bramble pub

Brambles like an acidic soil, so I would make sure soil is acidic, and I would fertilize now, as they will turn even more yellow, possibly die. Use an acidic fertilizer like Holly-tone or probably even better to work right now is miracle grows acid fertilizer. Mir-Acid or something like that?

"I am afraid to fertilize my blackberries as they are huge this year "

They do grow huge! Most of my canes died to winter damage but I will get about 50. Enough to try them all.
All the canes died on my triple crown (I tried berries last year, wow, I like them a lot! No berries this year).
It grew 4 runners besides the main crown, so I have 5 of them now! I'm going to tie the canes together and put chicken wire around them, fill with leaves to protect it this winter.

I covered my TC with multiple layers of burlap, didn't lose a cane this winter even though bitter cold with no snow cover early on. Just lay them down on the (mulched) ground and cover.

Mrs.G,

Would you care to snap a pic of thos huge TC's? I'm trying to determine spacing and trellising (if needed)

Thanks!