Thuja occidentalis 'Nigra' - Dark Green American Arborvitae

Thuja occidentalis 'Nigra' provides shelter for birds and small wildlife, offering a safe nesting site within its dense foliage. The small cones produced by the tree may also attract certain bird species. In addition, deer tend to avoid Nigra, making it a great choice for deer-prone areas.

• Seasonality: Evergreen; retains its dark green color year-round.
• Flowering Season: Conifers like Thuja occidentalis 'Nigra' do not produce significant flowers. Instead, they develop small, inconspicuous cones.

The foliage of Thuja 'Nigra' consists of flat, scale-like leaves that are dark green and dense, giving the tree a lush, full appearance. The leaves grow in sprays, creating a soft, feathery texture that adds visual appeal and makes the tree ideal for hedges and screens. The foliage remains vibrant even during the cold winter months, making this a standout evergreen in the landscape.

Although 'Nigra' is not known for its flowers, it produces small, round cones that mature in the fall. These cones are about ½ inch long and are brown when mature.

• Planting Season: Best planted in early spring or fall when temperatures are moderate, allowing the tree to establish its root system before extreme weather sets in.
• Soil Requirements: Thrives in well-drained, moist soil but is adaptable to various soil types, including clay and sandy soils. Prefers slightly acidic to neutral soil.
• Spacing: Space plants 4-6 feet apart for privacy screens or hedges, allowing for their mature spread.

Planting Instructions:

1. Dig a hole twice as wide and as deep as the root ball.
2. Place the tree in the hole, ensuring that the top of the root ball is level with the soil surface.
3. Backfill with soil, tamp down gently, and water thoroughly.
4. Apply mulch around the base to help retain moisture and suppress weeds.

Pruning is generally not required to maintain the tree’s natural shape, but it can be pruned in late winter or early spring to control size or shape if desired. Light trimming to remove dead or damaged branches can help keep the tree healthy and promote dense growth. Avoid heavy pruning, as this can slow growth.

Thuja 'Nigra' requires regular watering, especially during the first growing season to establish a strong root system. Water deeply once or twice a week, depending on weather conditions. Once established, it is more drought-tolerant but still benefits from consistent moisture, particularly during hot, dry periods.

This arborvitae thrives in full sun but can tolerate partial shade. For the best foliage color and growth, plant in a location that receives at least 6 hours of direct sunlight per day. In partial shade, growth may be slower, and the foliage color may not be as intense.

There is no need to harvest from Thuja occidentalis 'Nigra', as it is primarily grown for its ornamental qualities. The small cones that develop are not typically used for decorative or commercial purposes.

Fertilize in early spring with a balanced, slow-release fertilizer (such as 10-10-10) to encourage healthy growth. Established trees may only need fertilization every few years, especially if planted in nutrient-rich soil. Avoid over-fertilizing, as this can lead to weak growth.

• Mulching: Apply a 2-3 inch layer of mulch around the base of the tree to retain moisture, reduce weeds, and protect the roots from temperature fluctuations. Keep mulch away from the trunk to prevent rot.
• Pest and Disease Resistance: Thuja 'Nigra' is relatively pest-resistant but may occasionally be affected by bagworms or spider mites. Regular inspections and good air circulation around the tree can help prevent pest infestations.
• Winter Hardiness: Very cold-hardy and capable of withstanding harsh winter conditions without losing its color or form.