Raspberries are similar to blackberries in appearance and plant structure. The fruit are borne on two-year-old canes, called flurocanes. Like blackberries, these canes should be cut down after they bear fruit. From the moment the canes sprout and through their first year of life, raspberry canes are called primocanes. A trellis can help you separate primocanes from flurocanes and can hold these canes upright to promote good air circulation. Constructing a raspberry trellis is simple.
Drive wooden stakes into the ends of your raspberry hedgerows to mark the line of the row. Your rows should run north to south to help the plants absorb the most light.
Tie a string between the two wooden stakes to help set the trellis posts in a straight line. Dig post holes into the ground that are at least 24 inches deep. The holes should be spaced every 20 feet along a raspberry hedgerow. Place a pressure treated fence post into the hole and fill in around the hole with dirt to hold the post in place.
String a nine gauge fencing wire along each side of the fence posts at a point 4 feet off of the ground. Twist the wire around the end posts and then twist the loose wire around the taut wire string to fasten it.
Secure the wire to each T-post by hammering fencing staples around the wire and into the fence posts.
Plant the raspberries beneath the trellis. Tie half of the flourocanes to each side of the trellis loosely with twine as they grow tall enough to reach the trellis.