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Kiwi plants are dioecious: each vine is either male or female, and only the female carries fruit. The male produces pollen and nothing else. This is the single fact that catches out most people who plant a kiwi, because the vine grows beautifully, covers the pergola, flowers heavily, and drops every flower without setting a thing. By the time that pattern is obvious you have usually lost three or four years.
So plant at least two: one female for the fruit and one male within pollinating distance. If you already have a vine in the ground and it has flowered without setting, look at the flowers before you blame the weather. Female flowers have a pale, sticky, many-armed structure in the center and a ring of stamens that carry no useful pollen. Male flowers have a dense boss of stamens heavy with yellow pollen and no swollen base behind the petals.
Nurseries usually label sex on the pot, but labels get swapped and seedling-raised plants are a lottery: a plant grown from kiwi seed has a fifty-fifty chance of being male and will not tell you which until it flowers, three to five years on. Buy grafted, named, sexed plants and you know what you have from the day it goes in.
| Feature | Male vine | Female vine |
|---|---|---|
| Flower center | Solid mass of stamens, no swollen base | White sticky styles radiating from a small green ovary |
| Pollen | Abundant, dusty yellow | Present but sterile |
| Flower count | Usually in clusters of three or more | Often single, sometimes threes |
| Purpose in the garden | Pollen only, prune hard after bloom | All the fruit |
| How many you need | One per six to eight females | As many as the structure will hold |
Build the structure before the vine, not after
A mature kiwi is not a climbing plant in the way a bean or a clematis is. It is a woody vine that puts out twelve to twenty feet (4 to 6 m) of new growth a year, builds a trunk as thick as your wrist, and in full leaf with a crop on carries several hundred pounds of wet weight. A trellis panel screwed to a fence will be pulled off the fence. An arch made from thin tube will fold. Whatever you build has to be permanent, because you cannot take the vine down to fix it later.
Two structures work well in a garden. A pergola or overhead arbour lets the arms run out along the top and the fruit hang underneath where you can see and reach it, and it gives you shade to sit in. A T-bar, which is a stout post with a crossarm about six feet (1.8 m) up and two or three wires strung along the row, is easier to prune and is what commercial growers use. Either way use pressure-treated 4x4 posts or larger, set two to two and a half feet (60 to 75 cm) deep in concrete, and 12 gauge galvanised wire.
Allow the space honestly. One female needs fifteen to twenty feet (4.5 to 6 m) of run. If your whole structure is eight feet long, plant one female and one male and accept that you will be cutting hard every winter, or grow a hardy kiwi type, which is smaller in leaf and fruit but only slightly less vigorous.
Set the posts and string the wires before the plants arrive. Trying to dig post holes around an established root system, or to thread wire through a vine already in leaf, is miserable work and damages the plant.
Site and soil
Kiwi wants full sun, shelter from wind, and drainage above everything else. The roots are fleshy and shallow, mostly in the top twelve to eighteen inches (30 to 45 cm) of soil, and they rot in ground that stays saturated. Heavy clay or a hollow where water sits will kill a vine slowly over two or three seasons; on that kind of ground plant on a raised mound eight to twelve inches (20 to 30 cm) high and several feet across.
Wind is the second thing people underrate. Young kiwi shoots are brittle and snap at the base in a gust, and a summer wind on a big canopy tears leaves and scuffs fruit. A wall, a hedge or a fence on the prevailing wind side is worth more than an extra hour of sun.
Soil should be deep, rich in organic matter and slightly acid, around pH 6.0 to 6.5. Work a few buckets of compost through a wide area rather than digging a rich pocket in poor ground, because a pocket becomes a sump. Kiwi is sensitive to salt and to heavy doses of concentrated fertilizer near the trunk, so keep feed spread wide and light in the first year.
| Requirement | Target | What goes wrong if you miss it |
|---|---|---|
| Sun | Six or more hours | Thin growth, few flowers, poor sugar |
| Drainage | Water gone from a test hole within a few hours | Root rot, sudden collapse in midsummer |
| Soil pH | 6.0 to 6.5 | Yellow leaves between the veins on alkaline ground |
| Shelter | Windbreak on the exposed side | Snapped shoots, scuffed fruit, torn leaves |
| Spacing between females | 15 to 20 ft (4.5 to 6 m) | A tangle you cannot prune or pick |
| Distance to the male | Within about 30 ft (9 m) | Poor set on the far end of the row |
Getting the plants in
Plant while the vines are dormant, in late winter or very early spring in a mild climate, or after the worst frosts have passed where winters are hard. Container-grown plants can go in later, but a vine planted in summer heat needs watering all season and gets away far less well.
- Dig wide, not deep Make the hole two to three times the width of the root ball and no deeper than it. Kiwi roots run sideways. A deep hole in unimproved soil settles and buries the crown, which invites rot at the collar.
- Keep the graft union above ground On a grafted plant, set the union two to three inches (5 to 8 cm) clear of the finished soil level. Buried unions throw rootstock suckers, and rootstock seedlings are frequently the wrong sex.
- Backfill with the soil you dug out Mix in a little compost but resist a heavily amended backfill. Firm it in stages with your heel, water in hard to settle the soil around the roots, then top up any sinkage.
- Run one shoot straight up to the wire Choose the strongest shoot, tie it loosely to a cane running up to the top wire, and rub off everything else below the wire. You want a single clean trunk. Trying to grow two trunks makes a permanent congested mess at the head.
- Mulch, but keep it off the stem Two to three inches (5 to 8 cm) of bark or compost over the root area conserves the moisture those shallow roots need. Pull it back four inches (10 cm) from the trunk so the collar stays dry.
- Cage the stem against cats Wrap wire mesh or a rigid sleeve around the lower trunk before you walk away. Cats are drawn to kiwi stems and will shred a young plant to the ground in a night. This is not optional in a neighborhood with cats.
Write down what went in where
Kiwi is the crop where records pay for themselves, because nothing about it happens quickly. Note which plant is male and which is female, and exactly where each one stands, before the labels fade and you are guessing four years later. Record the planting date, whether the plant was grafted or on its own roots, and the height of the trunk when you tied it up.
From the first spring, note the date each vine breaks bud and the date it flowers. Those two dates are the ones you will want when you eventually ask whether your male and female overlap in bloom, which is the usual cause of a female that flowers well and fruits badly. Two or three years of dates make the answer obvious; memory never does.