Raspberry Supports: Post and Wire Systems That Actually Hold a Loaded Row

Why raspberries need support at all

A summer-fruiting cane reaches 5 to 7 feet (1.5 to 2.1 m) and carries its fruit on side shoots along most of that length. Loaded with fruit and soaked by rain, an untied cane arches over until the tips touch the soil. The fruit that ends up on the ground is eaten by slugs or ruined by soil splash, and the arched cane shades everything behind it.

There is a second reason that matters more over time. A tied row is a row you can walk down and see through. Canes are spaced, air moves, and you can spot the first orange rust pustule or the first blighted cane while it is still one cane. An untied thicket hides all of that until it is a bed-wide problem.

Autumn-fruiting types are shorter and stiffer, and a well-thinned block of them often stands unaided. They still benefit from something to lean on, because the fruit is at the cane tips where the leverage is worst, and a row that flops into the path gets trodden on.

Put the posts in before the canes go in

Install the framework at planting time. Driving a post through an established raspberry root system tears roots and starts a fresh crop of suckers exactly where you least want them, and you cannot get a rammer in among standing canes without breaking them.

Use posts at least 8 feet (2.4 m) long so that 2 feet (60 cm) goes into the ground and you still have 6 feet (1.8 m) of usable height. Space them 10 to 12 feet (3 to 3.6 m) apart down the row, and brace or angle the two end posts, because all the tension in the wires pulls on those two and a leaning end post makes the whole row sag.

The single fence, and how to tie to it

For most gardens the single post-and-wire fence is the right answer: three horizontal wires on a line of posts, with the canes tied flat against them. It costs least, it takes up the least room, and it is the easiest to pick from because every cane is in one plane and you can see through the row.

Run the wires at 2 feet 6 inches (75 cm), 4 feet (1.2 m) and 5 feet 6 inches (1.65 m). Tie each cane individually to each wire it crosses. Individual ties take longer than looping a length of string down the row, but a single cane can then be cut out at pruning time without releasing its neighbors, and that alone saves the time back.

1. Tie in as the canes grow, not all at once Walk the row two or three times through the season and tie in the new canes while they are still flexible. Canes left loose until winter have set into a curve and snap at the base when you straighten them.
2. Use a figure of eight Cross the twine between the cane and the wire so the two never rub. A tie that pulls the cane hard against the wire chafes through the bark and lets cane blight in.
3. Space the canes along the wire Aim for 4 inches (10 cm) between canes. Fan them slightly rather than bunching them at the stool, and each cane gets light along its whole length.
4. Leave the tie loose enough for a finger Canes thicken through the season. A tie that was snug in spring is a tourniquet by midsummer, so leave room for a finger between tie and cane.
5. Check the tension in late winter Retighten the wires before growth starts. A slack wire lets the whole row lean, and by the time it is carrying fruit it is too late to fix.

Twine ties should be soft and biodegradable where possible, since at pruning time you cut cane and tie together and it all goes in the same barrow. Plastic clips get lost in the mulch and turn up for years.

Other systems, and when they earn their extra cost

The single fence is not the only option and there are situations where a different arrangement is clearly better. The choice is essentially a trade between the room you have, the amount of fruit you want, and how much building you are willing to do once.

For a heavy summer-fruiting row where space allows, a T-trellis is the most productive layout. Crossarms 2 feet (60 cm) wide at the top of each post carry a wire at each end, and the fruiting canes are tied out to those two wires while the new canes grow up the middle. Fruit hangs on the outside where it gets sun and where you can pick from a standing position, and pruning is trivial because the two ages of cane are physically separated.

The parallel-wire method, with a wire on each side of the row at 3 feet (90 cm) and 4 feet 6 inches (1.35 m), needs no ties at all: the canes are simply contained between the two wires. It suits autumn-fruiting raspberries well and is much faster, at the cost of a denser, less airy row.

Maintenance, and keeping a record of it

A support system is not finished when you build it. Wires stretch, posts rot at the soil line, and end posts pull inward year by year. Check the whole run once a year in late winter when the row is bare and you can see the structure, and deal with anything that has moved.

The post that fails is almost always an end post, and it almost always fails at ground level rather than at the top. Pushing hard on each post before growth starts finds the rotten ones while the row is empty and easy to work in, rather than in midsummer with fruit on the wires.

Note the year the posts went in and any you have replaced. Softwood posts last six to ten years in the ground, so a bed with a written install date tells you when to start budgeting for the next set instead of discovering it when a loaded row goes over in a gale.