Euonymus japonicus aka Japanese Spindle

Euonymus japonicus is a medium-sized evergreen shrub that typically grows 3-4.5 meters (10-15 feet) tall and 1.5-2.4 meters (5-8 feet) wide when cultivated. In ideal wild conditions, it can reach up to 7.5 meters (25 feet). The plant has a dense, oval, upright form and grows at a moderate rate. Dwarf cultivars like 'Microphyllus' stay much smaller at 60-90cm (2-3 feet), making them suitable for low hedges and borders.

Euonymus japonicus is primarily an outdoor shrub, thriving in USDA hardiness zones 6-9 (UK zone 7). It is exceptionally tolerant of coastal conditions, wind, and salt spray, making it ideal for maritime gardens. The plant performs best in sun-dappled conditions with afternoon shade in hot climates, though it tolerates full sun to fairly deep shade. It is commonly used for hedges, foundations, and screening in landscapes.

Euonymus japonicus is cold hardy to USDA zone 6 (down to -23°C/-10°F) and heat tolerant through zone 9. It thrives in temperate climates and performs well in both warm and moderately cold conditions. In hot summer climates, it benefits from afternoon shade to prevent leaf scorch. The plant is notably tolerant of maritime conditions and coastal temperatures.

Euonymus japonicus is highly adaptable to various humidity levels. It thrives in coastal areas with high humidity and salt spray, but also tolerates drier inland conditions. The plant is notably resistant to maritime exposure. In low humidity environments, ensure adequate soil moisture and consider afternoon shade to reduce stress.

Euonymus japonicus produces small, inconspicuous, four-petaled greenish-white flowers in late spring to early summer (May-June). The flowers appear in flattened clusters (cymes) of 5-12 blooms and have a distinctive vinegary scent. While not showy, the flowers are followed by attractive pink capsule fruits with red arils in autumn, which provide ornamental interest and food for birds.

The flowers of Euonymus japonicus have a distinctive vinegary or slightly unpleasant scent when in bloom during late spring and early summer. The foliage itself is not notably fragrant. The scent is not strong enough to be noticeable unless you're close to the flowering plant.

Many cultivars of Euonymus japonicus have been developed, particularly variegated forms. 'Aureomarginatus' (Golden Euonymus) features dark green leaves with golden-yellow margins. 'Silver King' has silvery-white leaf margins. 'Microphyllus' is a compact dwarf variety (60-90cm) ideal for low hedges and borders. 'Green Spire' has a narrow columnar form (2.5m tall x 60cm wide). 'Microphyllus Variegatus' offers white-margined small leaves. Variegated cultivars may revert to green, especially with excessive fertility.

Euonymus japonicus tolerates heavy pruning and can be shaped into formal hedges or topiary. Prune in late winter or early spring before new growth begins (RHS Pruning Group 8). The plant can be cut back by 30-50% to encourage bushy, compact growth. For variegated cultivars, promptly remove any all-green reversion shoots to maintain variegation. Light annual trimming maintains hedge shape.

Euonymus japonicus can be propagated by seed or cuttings. Seeds require 3 months of cold stratification and may take up to 18 months to germinate. For faster results, take semi-ripe cuttings in July-August or hardwood cuttings in October. Root cuttings can also be taken in winter. Commercial propagation typically uses stem cuttings for reliable results and to maintain cultivar characteristics.

Euonymus scale is the most serious pest, causing yellowing leaves and branch dieback. Other common pests include mites, leaf miners, aphids, mealybugs, and caterpillars. Crown gall, stem dieback, and fungal leaf spots may also occur. The plant is notably resistant to honey fungus. Deer may browse on foliage.

Euonymus japonicus is pollinated by insects. The plant is hermaphrodite, meaning each flower contains both male and female reproductive organs, allowing for self-pollination. However, insect visitation improves fruit set. The small greenish-white flowers appear in late spring and attract various pollinators despite their inconspicuous appearance.

Euonymus japonicus has very limited edibility and should be approached with extreme caution due to toxicity. PFAF rates edibility at 1 out of 5. Young leaves can reportedly be boiled, and powdered old leaves have been used as food coloring. However, the seeds are poisonous and other plant parts may also be toxic. Given the plant's toxicity to humans and animals, consumption is not recommended.

Euonymus japonicus has limited traditional medicinal uses, rated 1 out of 5 by PFAF. The stem bark has been used as an antirheumatic, diuretic, and tonic in traditional medicine. In Chinese traditional medicine, the leaves were used to aid difficult childbirth. However, due to the plant's toxicity, self-medication is not recommended and any medicinal use should be under professional supervision.

Euonymus japonicus has notable industrial and cosmetic applications. The roots and stems yield up to 7% gutta-percha, a non-elastic rubber used historically as an electrical insulator and in plastics manufacturing. The plant has been cultivated commercially for this purpose in Russia and Spain. Leaf extracts are also used as ingredients in commercial cosmetic preparations. The plant is widely valued for hedging and topiary.

Yellow leaves on Euonymus japonicus are commonly caused by euonymus scale infestation, which causes leaves to yellow and drop. Check the undersides of leaves and stems for small white or brown scale insects. Other causes include overwatering leading to root problems, nutrient deficiencies (particularly iron in alkaline soils), or natural leaf drop on older inner foliage. Ensure good drainage and inspect regularly for pests.

Brown leaves on Euonymus japonicus can indicate several issues. Powdery mildew often causes browning as infections progress. Euonymus scale can cause brown spots and dieback. Leaf scorch from excessive sun exposure (especially in hot climates without afternoon shade) causes brown leaf margins. Winter cold damage may brown leaves in zone 6. Ensure proper watering, good air circulation, and inspect for pest or disease problems.

Euonymus japonicus naturally has a moderate growth rate, so don't expect rapid expansion. Slow growth beyond normal can be caused by heavy shade (which also reduces fruiting), poor drainage or waterlogged soil, severe pest infestations like euonymus scale, or compacted soil. Ensure the plant receives adequate light (dappled sun is ideal), good drainage, and regular inspection for scale insects.