Planting Japanese Staunton Vine: Support, Site and Why You Need Two

What you are planting

Japanese staunton vine, Stauntonia hexaphylla, is an evergreen woody climber with glossy compound leaves held on long stalks, cream to pale pink bell-shaped flowers in spring, and purple egg-shaped fruit about two to three inches (5 to 8 cm) long. It is a close relative of akebia and is often shelved beside it, but the two behave differently in the garden in two ways that matter. It keeps its leaves through winter instead of dropping them, so it screens all year and also catches winter wind all year. And its fruit stays shut when ripe rather than splitting open along one seam, so you judge ripeness from the outside and cut the fruit whole.

The pulp inside is white, translucent and very sweet, studded with hard black seeds you spit out. The skin is not eaten. A mature vine on a strong frame will carry a substantial crop, but getting to that point takes patience and, as the next section explains, more than one plant.

Treat it as a permanent structural planting rather than a fruit bush. Established stems thicken into woody ropes, the root system spreads, and moving a vine after its third or fourth year is not realistic. Everything below is about getting the first decision right.

Two plants, and they must not be the same plant

This vine sets fruit poorly, often not at all, from its own pollen. A plant and every cutting, layer or division taken from it are one individual as far as the flowers are concerned, so buying two plants off the same nursery bench is frequently buying one genotype twice. That is the single most common reason a healthy vine flowers year after year and never carries a fruit.

Buy from two different sources, or buy seed-raised plants, which are distinct individuals by definition. Plant them within about fifteen feet (4.5 m) of each other, and preferably let them climb the same frame from opposite ends so their flowering shoots meet in the middle. You will almost certainly be hand pollinating between them, and that job is far easier when both sets of flowers are within arm's reach on the same morning.

Note the origin of each plant on a tag and in your records at planting time. Two years later, when you are troubleshooting a poor crop, you will want to know whether you actually have two genotypes or two copies of one.

Building the support first

The vine climbs by twining, wrapping its stems around whatever it meets. It will not stick to a flat wall and it will not hold onto smooth wide posts. It needs wire, cane, rail, mesh or a branch to spiral around, and once it does, the stem tightens as it thickens. Over several years that grip will crush a thin sapling, deform a plastic-coated trellis and pull the top off a light timber arch.

Build for the vine you will have in ten years, not the one in the pot. Galvanised wire strained between masonry anchors, scaffold-grade timber, a chain-link fence or a heavy pergola all work. Because the plant is evergreen, the frame also carries a full sail of leaves through winter storms, which is a real wind load that a deciduous vine's frame never sees. Anchor accordingly.

Give the top of the structure some horizontal run. Flowers and fruit come from short shoots on wood that is lying more or less level or arching over, so a vine that only ever goes straight up a post flowers weakly at the very top and nowhere else.

Getting it into the ground

Plant in autumn in mild areas so roots establish through the cool season, or in spring once hard frosts are past where winters bite. Avoid planting into cold wet soil in midwinter and avoid the height of summer heat.

1. Dig wide, not deep Open a hole two to three times the width of the root ball and no deeper than its height. The roots run laterally and fairly shallowly, so loosened soil out to the sides is worth more than a deep pit. Set the top of the root ball level with the surrounding grade, never below it.
2. Improve drainage, not fertility Fork coarse organic matter or grit through the surrounding soil if it holds water. Do not put concentrated fertilizer or fresh manure in the hole. Excess nitrogen at planting buys you fast leafy growth and delays the first flowers by a year or more.
3. Set the plant twelve to eighteen inches out from the frame Plant a foot to eighteen inches (30 to 45 cm) away from the base of a wall or post, leaning the stems in toward the support. Ground right at the foot of a wall is dry and often full of rubble.
4. Tie in, do not twist in Guide the two or three strongest stems onto the lowest wires and tie them loosely with soft ties. Leave the vine to do its own twining above that point. Shorten any weak whippy growth to encourage branching low down, so the base of the frame does not end up bare.
5. Mulch and water in Water in thoroughly to settle the soil, then mulch two to three inches (5 to 8 cm) deep with bark or leaf mold, kept clear of the stems. Water weekly through the first two summers unless rain does it for you; an evergreen vine transpires in every month, so it never gets a fully dormant rest from drought stress.

Growing it in a container

Container growing is a legitimate option where winters are too cold to leave the vine outdoors, because a potted plant can be moved into an unheated garage, porch or greenhouse for the coldest weeks. Use a pot of at least fifteen gallons (about 55 liters) with a soil-based mix, and build a rigid obelisk or trellis into the pot itself so the whole assembly moves as one.

Accept that a container vine crops lightly. Root restriction limits the size of the framework, and the framework is what carries fruiting shoots. You will still need two pots, from two genetic origins, for any fruit at all.

Record the planting position of each plant, its source, and whether it was seed-raised or propagated vegetatively. If both turn out to be clones of one another, no amount of hand pollination will produce fruit, and the fastest fix is to add a third plant from a different origin as soon as you know.