Gadenin日本語Get the appSelf-incompatible means exactly what it says
Haskap flowers carry both male and female parts, which fools a lot of gardeners into assuming the plant can look after itself. It cannot. The species carries a self-incompatibility system that recognizes and rejects its own pollen, and pollen from any plant that is genetically identical to it. Rejected pollen germinates on the stigma and then stalls partway down the style, so the ovary is never fertilized and the flower drops or produces a shriveled berry with no viable seed.
The practical consequences are worth stating bluntly. A single bush, however large, well fed and healthy, gives you almost nothing. Two bushes propagated as cuttings from the same original plant are one plant in two places and give you the same nothing. Two plants that are genuinely different but flower two weeks apart in your garden also give you nothing, because pollen has to be shed while the other plant's flowers are open and receptive.
Everything else about haskap, its hardiness, its early ripening, its indifference to soil pH, is forgiving. This one thing is not. If your bush flowers heavily each spring and the berries never amount to anything, look at pollination first and stop adjusting the feed.
| Symptom | Likely cause | What to do |
|---|---|---|
| Heavy bloom, almost no fruit set | No compatible partner in range | Add a genetically different plant that blooms at the same time |
| Fruit set only on one side of the bush | Partner too far away or poor insect activity | Move or add a partner closer; plant early flowers nearby |
| Small numbers of tiny, lopsided berries | Partial pollination, few seeds set | More partners, better overlap |
| Good set one year, none the next | Bloom windows drifted apart in a warm or cold spring | Add a third plant to widen the overlap |
| Set collapses after a cold snap during bloom | Pollinators grounded, not frost damage | Nothing to do that season; hand pollinate next time |
Bloom overlap is the thing to watch, not the calendar
Haskap flowers extremely early, usually as the first fruit blossom in the garden, with paired creamy tubular flowers opening while the buds on most other fruit are still tight. The whole bloom period on one plant runs roughly 10 to 20 days depending on temperature; a warm spell shortens it sharply and a cold, gray spring stretches it out.
Because different plants start at slightly different points, the overlap between any two of them varies year to year. In a mild spring one plant may be nearly over before the other opens. This is why a group of three or four different plants is more reliable than a pair: with three, one of them is almost always in step with each of the others.
Observe your own plants rather than trusting any general timing. Note the day the first flowers open on each bush and the day the last ones go over. Two seasons of that record tells you precisely which of your plants actually overlap in your garden and whether you need to add another to bridge a gap. It is the single most useful thing you can write down about haskap.
Getting insects to work in cold weather
Blooming first has a cost. The flowers open when the weather is still cold, often windy and wet, and honeybees barely fly below about 55F (13C). Bumblebees do, working from around 40F (5C) and in light rain, which makes them the main pollinator of haskap in most gardens. The flowers themselves are unbothered by the cold and tolerate frost down to roughly 20F (minus 7C) once open, so a poor set after a cold snap is almost always a shortage of flying insects rather than damaged flowers.
You can improve the odds. Plant early nectar sources near the haskap so that bumblebee queens are already foraging in the area when the bushes open. Leave rough grass, a log pile or an undisturbed bank nearby, because bumblebee nests are local and a colony sited fifty feet away is worth more than a hive a mile off. Site the bushes out of the coldest wind, in a spot that catches morning sun, so the flowers warm early and insects arrive when the pollen is fresh.
Do not apply any insecticide to a haskap or anything flowering near it during bloom. The window is short, the pollinator population is small and cold-limited, and losing a few days of insect activity costs you the crop.
Hand pollination when the weather refuses to cooperate
If bloom coincides with a week of cold rain, or you have only two plants and want to make certain of the overlap days, hand pollination works well and takes minutes. The flowers are large enough to handle easily and the pollen is plentiful.
The one thing hand pollination cannot fix is a missing partner. Moving pollen around a single bush, or between two identical plants, achieves nothing at all. Check that you actually have two distinct plants before spending the morning with a brush.
- Work in the middle of a mild day Pick the warmest, driest part of the day, when the flowers are fully open and the pollen is dry and loose. Wet pollen clumps and transfers badly, so skip a morning after rain and wait for the flowers to dry.
- Collect pollen from the partner plant Take a soft artist's brush or a cotton bud and roll it inside several freshly opened flowers on one bush until you can see pollen on the bristles. A pinch of picked flowers held in one hand works just as well and is quicker.
- Transfer to the other plant, then reverse Dab the brush into the open flowers of the second bush, touching the central stigma of each. Then take a clean brush, or the picked flowers from the second plant, and go back the other way. Both bushes need pollen from the other to crop, so do both directions.
- Repeat every two or three days through bloom Individual flowers are receptive for only a few days, and new ones open through the bloom period. Two or three passes across the window catch far more of the flowers than one thorough session on a single day.
Keep a short bloom log each spring: for every plant, the first open flower, the peak, and the last. Add the weather during bloom and a note on whether you saw bees working. After two seasons that log explains almost every good and bad haskap crop you will ever have, and it tells you exactly where a third plant should go.