Gadenin日本語Get the appBuild for the wind, not for the weight
By late summer a ten foot run of runner beans is a solid wall of leaf that catches wind like a sheet of plywood. The crop itself weighs very little by comparison. Almost every collapse happens in a summer squall, usually at night, usually just as the plants come into full pod, and a structure that felt perfectly firm in early summer goes over because the leverage at the top has quadrupled since then.
The two failures are always the same: canes not driven deep enough, and no rigid connection along the top of the row. Fix both at the start and the structure will stand through the season without being touched. Trying to lift a fallen row of runner beans back up is largely a waste of effort, because the stems kink and the flowers that were forming abort.
Runner beans climb by twining counter-clockwise around anything up to about an inch and a half (4 cm) thick. Anything thicker and they cannot grip. That rules out fence posts and drainpipes unless you run string or netting over them.
- Drive the canes 12 inches (30 cm) in A foot of cane in the ground is the minimum in ordinary soil, more in light sand. Push, twist and lever until the cane will not move when you pull sideways on it at head height.
- Cross the canes below their tops Cross each opposing pair about eight inches (20 cm) below the top, not right at the tip. That leaves a V that a horizontal pole sits into and cannot slide out of.
- Lay a ridge pole in the Vs and lash it A single cane or length of timber running the whole length of the row, tied into every V, turns a line of independent canes into one rigid A-frame. This is the step most people skip and it is what actually holds the row up.
- Brace the ends diagonally Tie one extra cane from the top of each end pair down to the ground at 45 degrees, pointing away from the row. Without end bracing the whole frame can concertina lengthways.
Use soft string or garden twine at every joint and tie in a figure of eight rather than a simple wrap. Plastic clips slip on smooth canes as soon as the load comes on.
Height, and pinching the tops out
Runner beans will keep climbing to twelve feet (360 cm) or more if you let them. That is a mistake in a garden. Set the structure so the top of the crossing point is at seven to eight feet (210 to 240 cm), which is the highest most people can pick without a step, and pinch out the growing tip of each plant when it reaches the top.
Pinching the tip is not just about reach. It stops the plant putting energy into more vertical stem and pushes it into side shoots lower down, which is where the flowers are. A stand that is allowed to run away puts its pods in a tangled mat above head height where you cannot see them, and pods you cannot see become pods you fail to pick, which is exactly what shuts flowering down.
Side shoots will appear along the whole length of the main stem after pinching. Leave them. There is no pruning to do on a runner bean beyond that one pinch at the top.
| Structure | Working height | Best used for |
|---|---|---|
| Double row of crossed canes with ridge pole | 7 to 8 ft (210 to 240 cm) | The standard for a productive row. Pick from both sides |
| Wigwam of six to eight canes | 6 to 7 ft (180 to 210 cm) | Small plots and windy sites. Very stable, harder to pick inside |
| Netting between two stout posts | 6 ft (180 cm) | Long runs. Posts must be concreted or driven 18 in (45 cm) |
| Strings from a top wire to ground pegs | 8 ft (240 cm) | Greenhouse and hoop house walls. Cheap to renew each year |
Getting the plants onto the support
Young runner beans do not always find the cane on their own. The shoot circles slowly, roughly one full turn every two hours, feeling for something to grip, and if the cane is more than a couple of inches away it will sprawl along the ground instead. Check every plant once a week while they are short, and wind any loose shoot around its cane by hand.
Wind it counter-clockwise when viewed from above. This is not superstition: runner beans twine in one direction only, and a shoot tied the wrong way unwinds itself within a day or two and falls off. Once a plant has three or four turns on the cane it will carry on unaided to the top.
If a shoot snaps while you are winding it, cut it back cleanly to the lowest pair of leaves. The plant will send up a replacement from the base within a fortnight and will still crop, just later than its neighbors.
Keeping the frame useful next year
At the end of the season cut the vines off at ground level and leave the roots in the soil, then pull the canes and scrub the bottom foot of each one before storing them dry and under cover. That bottom foot is where soil-borne rots overwinter, and a cane stored wet with soil on it goes soft and snaps mid-season the following year.
Note in your records which end of the row went over, if any did, and which way the wind was coming from. Prevailing wind at your site is consistent year to year, and a single extra brace on the correct end is usually the whole fix. Record the finished height of the frame too, so you can repeat it rather than guessing again next spring.