No fruit on blackberries and straw as mulch in vegetable garden
1. I planted a blackberry patch four years ago from slips given me by a master gardener at Derwood. I planted them in a backyard plot with good sun exposure. The soil was a converted grass backyard with poor soil content, but I double-dug the plot and added considerable manure and compost for a year or so before planting the berries. I have had declining fruit production since the first year, and this year I only got about a pint of berries from the very strong plants pictured here (5-6' high, row is 8' long). I cut the plants back last winter to 6" or so, and they grew back strongly but without fruit to speak of. My neighbor who receives even less sun than I do had a bumper crop. I have added no fertilizer of any kind. Any advice? 2. Do you recommend straw for weed control in vegetable gardens? Thank you very much!
1. It sounds like pruning is the problem.
Canes are biennial. The canes, typical biennial life-cycle is as follows: Each spring, canes known as primocanes emerge, grow tall, put out lateral branches, and overwinter. In the second growing year, the canes, now called floricanes, produce flowers and fruit. Floricanes die after fruiting and must be removed eventually. Usually, this is done in late winter before new canes begin coming up.
So, cut down to the ground the old (dead or dying canes) in late winter. Do not prune out the one year old canes that came up the summer before. Those newer canes will be greener. Those are the canes that will flower and produce blackberries. After they produce berries, then they, too, will die and need to be removed.
Read slowly through our bramble info: http://extension.umd.edu/growit/fruit-profiles/raspberries-and-blackberries#blackberries Each kind of bramble is handled somewhat differently, so it's a lot to absorb.
Also do a soil test of the blackberry patch. (Search 'soil testing' on our website for how to collect the sample and where to mail it.)
2. Straw can make a nice attractive mulch. It usually has to be quite thick in order to be effective. Laying 3-4 layers of newspaper under the straw will give you a solid, weed proof barrier that can be more satisfactory that the straw alone. (The newspaper decomposes by the next growing season.) Be sure you get clean straw without weeds that have weed seeds.