Growing and Caring for Common Juniper: A Comprehensive Guide
Plant Overview
Common juniper (Juniperus communis) is a versatile evergreen conifer native to the northern hemisphere. Known for its adaptability and hardiness, it has become a popular choice for landscaping and gardening.
Types and Varieties
While less common in cultivation than its counterpart, Chinese juniper, there are still a wide range of common juniper cultivars available. These include:
- Juniperis communis ‘Gold Cone’: Columnar form with light greenish leaves
- Juniperis communis ‘Repanda’: Prostrate groundcover form
- Juniperis communis ‘Compressa’: Upright, cone-shaped shrub
- Juniperis communis ‘Hibernica’: Pillar-shaped shrub
- Juniperis communis ‘Blue Stripe’: Prostrate form with blue-striped leaves
Planting and Care
Planting:
- Plant in well-draining soil with a pH between 4.0 and 8.0.
- Dig a hole twice as wide as the root ball and amend the soil with organic material.
- Position the shrub at the same height it was in its container.
Watering:
- Common junipers are drought-tolerant but prefer moist soil.
- Do not overwater, as they cannot withstand waterlogged conditions.
Sunlight:
- These sun-loving plants require full sun for optimal growth.
Temperature:
- Hardy in USDA zones 2 to 7, most common juniper varieties can withstand temperatures as low as -49 degrees Fahrenheit.
Fertilization:
- Common junipers are light feeders and do not require regular fertilization. A yearly application of a slow-release shrub and tree fertilizer in late winter or early spring may be beneficial.
Pruning:
- Pruning is generally not necessary, but can be done in late winter to remove diseased or broken branches.
- When pruning for shape, cut individual branches back to an upward-growing side branch.
Propagation
Rooting Cuttings:
- Take 4- to 6-inch cuttings from the tips of branches in late summer.
- Dip the cut ends in rooting hormone and plant in a porous potting medium.
- Keep the cuttings moist and in a sheltered location until roots develop (6-12 weeks).
Growing from Seed:
- Common junipers are dioecious, meaning they have male and female plants. Both must be present for cross-pollination and fruit production.
- Harvest ripe berries (turned purple/black) and sow the seeds directly into the garden or stratify them for up to 120 days before planting.
- Germination rates are poor, so sow several seeds at once.
- Seedlings will grow slowly and may take up to two years to reach a suitable size for transplanting.
Potting and Overwintering
Potting:
- Small upright varieties of common juniper can be grown in containers.
- Use a well-draining potting mix with added sand or perlite.
Overwintering:
- In colder climates, potted junipers may need to be moved indoors or covered with mulch for the winter.
- Avoid keeping them indoors for extended periods, as they require a cold dormant period.
Pests and Diseases
Common Pests:
- Bagworms
- Juniper scale
- Aphids
Common Diseases:
- Juniper blight
- Twig blight
- Cedar apple rust
Problem-Solving
Tips of Branches Dying:
- Check for fungal diseases (blight) and prune off affected branches.
Leaves Die Back Along One Side:
- Indicates winter burn from desiccation. If severe, the shrub may die.
Branches Die, One at a Time:
- Phytophthora root rot may be the cause. Prune away damaged branches and improve soil drainage.
Needles Turn Brown and Fall Off:
- May be caused by overwatering, underwatering, or pet urine.
Additional Uses and Considerations
Practical Uses:
- Juniper berries are used for flavoring gin, tea, and culinary dishes.
- The plant provides food and shelter for wildlife.
Comparison to Chinese Juniper:
- Common juniper has more needle-like leaves and bluish berries.
- It is better suited for colder climates than Chinese juniper.
Landscaping Applications:
- Common junipers are versatile shrubs for mass plantings, groundcovers, rock gardens, and general garden use.
- Different cultivars offer a range of forms and sizes to suit specific landscaping needs.
Edible Berries:
- Juniper berries are edible, but caution is advised as some juniper species have toxic berries.
- Berries take 2-3 years to ripen and may be scarce due to birds consuming them.