Thuja, commonly known as arborvitae or cedar, is a genus of evergreen coniferous trees and shrubs in the cypress family (Cupressaceae) celebrated for its dense, scale-like foliage and conical shape. These plants are native to North America and East Asia. They are popular in landscaping and gardening due to their attractive foliage, versatility, and adaptability to various growing conditions.
Planting Calendar
Thuja can be planted throughout the year but grow best when planted in spring and autumn, giving it time to establish its roots before the heat of summer.
Prepare
Thuja provide year-round greenery and make excellent choices for hedges, screens, or ornamental plantings. Thuja plants vary in size from low, spreading shrubs to tall trees, depending on the species and cultivar. With their easy maintenance and timeless appeal, Thuja trees are a popular selection for gardeners looking to add structure, form and privacy to their landscapes. They even look great in pots on the deck.
Position
Thuja prefers well-drained soil and full sunlight. Thuja can tolerate a range of temperatures but might struggle in extremely hot or dry conditions. If you're in a very hot area, provide afternoon shade and regular watering.
Soil
When planted into the ground Thuja prefer a free-draining soil that is rich in organic matter. To improve the organic content in your soil, break up the soil and add Kings Compost and Kings Sheep Pellets then mix together well. When growing in containers, plant into Kings Container mix. This mix contains Saturaid, which helps with moisture retention in the soil.
Plant
When planting into the ground, ensure the plants is well watered then, gently tap the plant out of its pot. Dig a hole twice the depth and width of the plant’s root ball. Mix Kings Compost into your existing soil at a 50/50 ratio, add Kings Sheep Pellets then mix together. Backfill the hole with this soil, so that when planted the top of the plant’s roots sit level with the surrounding ground. Firm the soil down gently and water in well with Aquaticus Organic Garden Booster. In heavier clay soils, where drainage is likely to be an issue, plant onto a raised mound and sprinkle Gypsum Clay Breaker into the bottom of the hole, this helps slowly condition the soil and help to break down the clay. When planting into containers plant into Kings Container Mix, as this has water retention crystals in it, which will help in keeping the soil moist.
Care
Watering
Watering is essential especially in the first year of planting to allow the roots to get well established. Water slowly, allowing the water to sink down into the roots, rather than just allowing it to run off the top of the surface of the soil, aiming to keep the soil moist during hot periods.
Feeding
For strong healthy roots and plants, apply monthly applications of Aquaticus Organic Garden Booster, from Spring through to the end of Autumn, this encourages root growth and increases the microbial activity in the soil. Monthly applications of Kings Sheep Pellets will help with soil conditioning and plant health.
Protecting
Thuja can be affected by root rot in wet conditions, good drainage is key.
Mulching
Mulching around plants can help conserve moisture, regulate soil temperature, and reduce weed growth. Mulch around the base of the plants (making sure it is not in direct contact with the trunk or base of the plant) with Living Earth More than Mulch. Replenish mulch each spring.
Spraying
Bagmoth caterpillars can show up, if so spray with Groventive Garden.
Pruning
Prune to remove any brown growth or to maintain shape.
General Care
When using sprays, chemicals or fertilisers always read the label and follow the instructions. Apply sprays in the evening to avoid harming beneficial insects
Frequently Asked Questions
What is the best location to plant Thuja?
Thuja trees prefer a sunny location but can tolerate partial shade. Ensure the area has well-draining soil to prevent waterlogging.
How often should I water my Thuja?
Watering is essential especially in the first year of planting to allow the roots to get well established. Water slowly, allowing the water to sink down into the roots, rather than just allowing it to run off the top of the surface of the soil, aiming to keep the soil moist during hot periods.
How do I prune Thuja?
Prune your Thuja in late spring or early summer. Remove any dead or diseased branches, and trim for shape and size. Avoid cutting into old wood, as it may not regrow.
How do I fertilise my Thuja?
For strong healthy roots and plants, apply monthly applications of Aquaticus Organic Garden Booster, from Spring through to the end of Autumn, this encourages root growth and increases the microbial activity in the soil. Monthly applications of Kings Sheep Pellets will help with soil conditioning and plant health.
What are common pests and diseases affecting Thuja?
Common pests include spider mites, aphids, and bagworms. Diseases can include root rot, especially in poorly drained soils, and leaf blight. Regular inspection and appropriate treatment will help manage these issues.