Arborvitae (Thuja) Care Guide

Hi, friends! Today I will tell you how I take care of my thuja trees.

⚡QUICK ANSWER: Plant arborvitae in well-drained soil with full sun to partial shade. Water deeply once a week, especially during dry spells. Mulch around the base to retain moisture. Prune lightly in early spring to shape, avoiding cutting into old wood. Protect from heavy snow and ice in winter.

🌞Light requirements

Arborvitae can grow well in both full sun and partial shade. In full sun, its needles develop a rich, deep green color.

However, partial shade is ideal, with about half a day of direct sunlight. This balance keeps the needles vibrant, supports overall plant health, and prevents yellow varieties from getting sunburned. The best locations are on the east or west side of a house, where the plant gets morning or afternoon sun but is protected during the hottest part of the day.

🌍Soil

Thuja can grow in many soil types, but it performs best in well-drained, slightly acidic soil.

If you have heavy clay soil, mix it with compost in a 1:1 ratio. This improves drainage, makes the soil looser for faster root growth, and naturally increases acidity. Compost also enriches the soil structure and serves as a natural fertilizer.

🌱Planting

When to plant?

Spring is the best time to plant arborvitae, ideally in mid to late March, though April also works well.

The first half of autumn is another good option, but plant at least one month before the first frost to allow roots to establish.

Avoid planting in summer. Early or late summer may work, but mid-summer heat, especially during heatwaves, often causes plants to fail.

Winter planting is not recommended, as arborvitae go dormant and shouldn’t be disturbed during this period.

How to plant?

Plant arborvitae on a cloudy day or when the sun is mild to reduce stress. Early morning or evening planting also helps the tree adapt more easily.

If it hasn’t rained the day before, water the tree thoroughly before planting.

Dig a hole twice as wide as the root ball. Place the root ball in the center, making sure the trunk is no more than 1 inch below the soil surface — only the roots should be covered. Fill the space around the roots with soil.

After planting, water deeply but gradually, keeping the soil evenly moist without flooding it.

💧Watering

For the first 1–2 years after planting, water your thuja whenever the top inch of soil feels dry, using at least one gallon of water each time.

After two years, the plant should be well-established and usually won’t need regular watering, as natural rainfall is often sufficient. Thuja can handle brief dry spells, but during extreme or prolonged drought, give it a deep watering to keep it healthy and looking its best.

🌼Fertilizer

Use slow-release fertilizers like Osmocote, which has a balanced NPK ratio and provides nutrients gradually, minimizing the need for frequent feeding.

Organic options, such as compost, are also excellent. You can mix compost into the soil during planting or spread it as mulch around the base. Always choose high-quality, store-bought compost, as poor or improperly prepared compost can harm your plants.

Avoid fertilizing in the fall, as it can trigger new growth that may be damaged by winter frost.

🌡️Diseases

Thuja is generally resistant to diseases, but problems can occur in crowded plantings or areas with poor drainage.

Watch for symptoms like dark spots on the needles, drying branches, or cracked bark.

If you notice these signs, prune the affected branches immediately using sterilized tools. Then, treat the plant with a fungicide designed for the specific disease.

🐛Pests

Thuja isn’t usually troubled by pests, but it’s important to stay vigilant. At the first sign of infestation, act quickly.

Horticultural oil works well for controlling most pests, while insecticidal soap is another effective and safe option.

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