Our raspberries were starts from Nourse, planted in trenches with compost added. The rows are six feet apart. In between the rows, the ground is covered with landscape fabric topped with pine bark chips for mulch. We have used straw mulch in the past, but it does tend to "compost" itself, and let more weeds come in.
The goal in renovating your raspberry bed is one good cane per foot for maximum berry size, flavor and plant health. This is what one faces come the spring snow melt:
It's fairly easy (if tedious) to prune out the little-finger-sized canes, the peeling, dead looking canes (they bore berries last year and won't again), and the ones growing outside your intended row. Once you've removed all of the definitely-unwanted canes, prune the tops down to your preferred height. For us, that is approximately 3 feet tall. Any taller, and the branches tend to bow down to the ground when full of berries... where local critters then pick more than I do!
So now your row should start looking like this:
If your plants are healthy, you have lots of strong, sturdy canes to choose from. This is where some "art" comes in.... you need to choose which canes to prune out (at the base again) until you're down to approximately one cane per foot. I pull back leaf mulch around the canes at this point. Once all of the branches are finally removed (our kids LOVE the bonfire :-) ), it's time to lightly rake the leaves off of the mulch (again, for plant health and less future compost for weeds to grow in). And you're almost there!:
Fertilizer needs to be added. Our llamas provide what we need for rich llama manure compost :-). Fish meal provides an added Nitrogen boost.
And the trellis either needs to be established, or the wires tightened, or the string replaced so all is ready for a heavy load of berries come summer! :-) (see above picture for our very simple design). You CAN do without a trellis, but picking is slower and trickier. ;-)
We throw out "semaspore" from Planet Natural a few times each May and June to naturally reduce grasshopper populations. Shiny bird tape tied here and there to flutter in the wind help repel birds. We really have no other pest problems with our raspberries here in southern Montana.
And your end result this summer will hopefully look like this (2012 crop)! :-) Happy Berry Growing!