Juniperus virginiana flowers from March to May. The fruits should be gathered in the fall (September-November) as soon as the berry-like cones become ripe. Red cedar trees come to seed-bearing age in 10 years, and they bear cones every 2-3 years. Seed collection can be done by stripping or picking the berries by hand from the trees, or by flailing the fruits to ground cloths. Be careful to pick only ripe berries. Since the number of filled seeds varies widely from tree to tree, it is important to test the seeds by cutting to determine percent fill. Seeds may be stored as berries or cleaned seeds.
The seeds can be recovered by macerating the fruits and floating the seeds to the top. The addition of detergent to the maceration water helps to separate seeds from the resinous fruits. Red cedar seeds store quite well. They should be dried to 10-20% moisture and stored in a sealed container at cold temperatures.
For best germination, seeds should be removed from the fruits, then the seed coat is softened by treating it with sulfuric acid for 120 minutes. After soaking the seeds in sulfuric acid, follow with 6 weeks of warm stratification at 20 to 30°C (70 to 85°F), or summer planting, then 10 weeks of pre-chilling at 4°C (40°F). Use of fresh seed reduced the warm stratification time. Rather than the acid treatment, two to three months of warm stratification could be used. As an alternative for cold stratification, the seed may be sown in the fall. Germination is delayed at temperatures above 15°C (60° F). Germination is often delayed in red cedar seeds, as seeds are consistently highly dormant.
Red cedar seeds are usually sown in the nursery in the late summer or fall, but may be sown in spring or summer. The seeds of most species should be sown in fall to take advantage of natural pre-chilling. Red cedar seeds are usually drilled in well-prepared seedbeds in rows 15 to 20 cm apart and covered with 0.6 cm of soil. In nurseries with severe climates, such as those in the Great Plains, considerable care must be taken to protect the beds with mulch and snow fences.
Viability of the seed varies considerably from year to year and among lots, but it is never much over 50 percent. Treated seed is usually planted in the spring, either in outdoor beds or in flats in the greenhouse. Two or three years are required to produce plants large enough to graft.
Juniperus virginiana – 14-18 seeds per 110 kg fruit, 96 seeds per gram.
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