Warm and then cold, moist stratification required. Upon receiving seeds, soak in warm water for 24 hours, then mix seeds with sterile moist substrate (vermiculite, perlite or moss) and place in a plastic bag or reusable container and leave at room temperature for 60 days, then refrigerate for 6-8 weeks. Once stratified, plant 1/8 deep. Do not let seedling dry out.
OR
Alternatively, seed can be sown outdoors, but can require up to two years to germinate.
Location
Winterberry will do well planted in a spot that offers either full sun or partial shade. Aim to plant the shrub somewhere that gets at least four hours of sunlight per day for optimal blooming.
This plant adapts to both light and heavy soils but performs best in acidic loam soil (pH 4.5 to 6.5) with a good level of organic matter. It does poorly in neutral to alkaline soil, which can cause fatal chlorosis (yellowing of the leaves). Feeding with an acid fertilizer can help modify this if a soil test shows your landscape offers neutral to alkaline soil.
Winterberry prefers fairly wet conditions. Do not plant it in dry soil or a dry climate unless you are willing to water frequently. This plant will require 1 inch of water per week, either through rainfall or irrigation.
Identifying Male and Female Plants:
Both plants will produce small green-white flowers in late spring, which will eventually turn to berries if properly pollinated. To tell the bushes apart, look at the center of the flowers—female plants will have a small green nub, while male plants will have pollen-bearing anthers.
Pruning & Care:
The plant blooms on old wood, which means the only time you should prune the bush is in late winter while the berries are still on the bush. Some pruning is recommended because these shrubs grow tall and can produce suckers.
Winterberry bushes only fruit when they're well established, which can mean as many as two to three years in the ground before they begin to have showy fruiting displays.
Learn more about cold stratification methods here.
