Berberis thunbergii "Joanna", 20 cm pot

• Species: Berberis thunbergii — Japanese barberry
• Variety: “Joanna” (introduced 2016)
• Height: 0.6–0.7 m
• Habit: dense shrub with arching branches
• Leaves: small, green speckled with white; pinkish tint in sun
• Flowers: yellow, in May
• Fruit: red berries in autumn, holding into winter
• Position: sun or part shade (colour is better in sun)
• Soil: undemanding, but drainage matters
• Dislikes: excess moisture and standing water
• Sold as: 20 cm pot
• Uses: low hedge, rockery, front of border, container
• Note: sharp thorns on the branches

Planting. A potted plant can go in throughout the season; spring and August–September are best. Dig a hole one and a half times the pot width and add sand or gravel at the bottom on heavy soil. Keep the root collar level with the ground. For a low hedge plant 3–4 per running metre.

Site. The more sun, the clearer the white-and-pink variegation; in deep shade the leaves simply turn green. Avoid hollows where water stands — wet soil is more dangerous to barberry than drought.

Water and mulch. Water weekly in dry spells during the first summer; after that the shrub copes on its own. Mulch (bark, wood chips) keeps moisture in and weeds out.

Pruning. None required — the variety holds its shape. In spring remove frost-damaged and dead shoot tips. For a denser hedge, trim lightly after flowering. Wear thick gloves.

Winter. The variety is hardy and copes with our winters. In the first winter after planting, mulch the root area; snow load does not break the branches.

Watch for. Leaf spot in crowded plantings and wet summers — thin out and keep air moving. Aphids appear occasionally in spring; wash them off with water.