Arborvitae in May: monthly care

Arborvitae thrives in full sun or partial shade, though plants grown in full sun develop denser, more compact foliage. It tolerates a wide range of soil types—loam, clay, and sandy soils all suit it—provided drainage is reasonable. Avoid waterlogged ground, which can lead to root rot. Plant container-grown arborvitae in March, April, May, September, or October. Autumn planting is often ideal because cooler, wetter weather helps roots establish without the stress of summer heat. Dig a hole roughly twice the width of the root ball but no deeper; the top of the root ball should sit level with the surrounding soil. Break up compacted soil at the base and sides of the hole to encourage roots to spread. If you're planting a hedge, space plants 40 cm apart for a dense screen. For specimen trees, allow at least 80–100 cm between plants to accommodate their mature spread. After positioning the plant, backfill with the excavated soil, firming gently to eliminate air pockets. Water thoroughly immediately after planting to settle the soil around the roots. Apply a 5–7 cm layer of organic mulch—bark chips or well-rotted compost—around the base, keeping it a few centimetres clear of the trunk to prevent rot. Mulch conserves moisture and suppresses weeds while roots establish. Newly planted arborvitae benefit from regular watering during their first growing season, especially in dry spells. Check soil moisture weekly and water deeply if the top few centimetres feel dry. Staking is rarely necessary unless planting in an exposed, windy site.

Arborvitae requires minimal pruning, but regular light trimming keeps hedges tidy and encourages dense growth. Prune in May, June, or September—avoid cutting during frosty weather or high summer heat. Late spring and early autumn are ideal because the plant is actively growing and will recover quickly. Use sharp bypass secateurs or hedge shears. For formal hedges, trim back new growth by about one-third, cutting just above green foliage. Never cut into old, brown wood; arborvitae does not regenerate readily from bare stems, and you risk leaving permanent gaps. Always leave some green growth on every branch. If you're maintaining an established hedge, a light trim once or twice a year—typically in late May and again in September—is sufficient. For specimen trees, pruning is largely unnecessary. Remove any dead, damaged, or diseased branches as soon as you notice them, cutting back to healthy wood or the main trunk. If a leader (main central stem) is damaged, select a strong lateral shoot, tie it vertically to a cane, and train it as the new leader. Thin out any crossing or rubbing branches to maintain good air circulation and an attractive shape. Avoid heavy pruning or drastic reshaping. Arborvitae responds poorly to hard cutbacks, and recovery is slow. If a hedge has become overgrown and bare at the base, it's often better to replace it than attempt renovation. Light, regular attention from an early age is far more effective than infrequent severe cuts.