Pruning Raspberry and Blackberry Plants (from about.com)

RASPBERRIES

What Kind of Raspberry are Your Pruning?
There are 2 bearing categories for raspberry plants:
1.Summer Bearing (floricane) Raspberries will provide 1 large harvest, usually in late summer or early fall. Summer bearing raspberries bear fruit on 2 year old canes, the canes that sprouted last season. Summer bearing raspberries can be further categorized as early season, mid-season and late season. The harvest period lasts about 4 -5 weeks.

2.Everbearing (primocane) Raspberries aren’t really everbearing, but they do generally have 2 harvests per season; one in mid-late summer and one in the fall. They fall crop will probably be a bit lighter and is on 1 year old canes of the current season. Many fall bearing raspberries bear so late in the fall that they are not practical for gardeners in short season climates.

How and When to Prune Raspberries
A Word of Caution: Wear thick gloves; raspberries have serious thorns. And use clean, sharp tools.


LATE WINTER / EARLY SPRING - (Before Bud Break)

•Prune all canes that bore fruit last year; they won’t fruit again. These will have grayish, peeling bark.

•Remove any canes that have grown outside the 12 - 18 inch designated row footprint.

•Remove any spindly or short canes.

•Thin so that there is about 4-5 of the healthiest, tallest and fattest canes left per foot along the length of the row.

•Tie remaining canes to your fencing.

•To force your everbearing raspberries to produce only one crop in the fall, prune back the entire raspberry bush in early spring. As the canes grow back in the summer, remove outside suckers and thin the canes to about 6 inches apart. Keep the sturdiest canes. This technique will give you a larger fall harvest and is good if you also have summer bearing raspberry bushes and you want to stagger the harvests.
SUMMER

•Prune dead, broken or diseased canes.

•Prune any canes that poke up outside your designated row area.
Of course, you can prune broken, dead, diseased or infested canes at any time of the year, the sooner the better.

BLACKBERRIES

Blackberries aren’t quite as enthusiastic growers as raspberries, but they will yield better with regular pruning. And as with raspberries, they can be prone to diseases that spread rapidly in unmaintained plants.
How and When to Prune Blackberries
Blackberries can also have dangerous thorns. Gloves are recommended and clean, sharp tools are also necessary. There are some modern blackberry varieties that are virtually thornless and they make pruning a lot less hazardous.

Newly Planted Blackberry Plants
Pinch or prune off the growing tips of all new canes to encourage side shoots (laterals). This is where next seasons blackberries will grow.

Maintaining Bearing Blackberry Plants
•FALL
•Prune out all canes that bore fruit, shortly after harvest. (It’s advisable to dispose of all clippings, either by burning or taking to the dump. Dead canes can spread disease.)

•EARLY SPRING
•Thin canes to about 5 - 7 per plant.
•Prune side branches on remaining canes to about 12 inches or 12 buds.
•Tie the pruned canes to your fencing.
As with raspberry plants, you can prune broken, dead, diseased or infested canes at any time of the year, the sooner the better.