Round-leaved Mullein (Verbascum rotundifolium): complete guide

Overview

Verbascum rotundifolium, known as round-leaved mullein or woolly mullein with round leaves, is a sunny plant from the Scrophulariaceae family. This species is native to southern Italy, Sicily, and North Africa, where it grows on dry slopes and rocky areas. The plant is highly valuable for gardens with warm, dry conditions. With its bright yellow flowers and characteristic round leaves, it forms a striking addition to Mediterranean and drought-tolerant garden plant compositions.

Appearance and bloom

Verbascum rotundifolium grows as a semi-rosette forming plant, usually 40-70 cm tall. The plant produces basal rosettes of distinctly round, woolly hairy leaves that are gray-green. The flower stems are unbranched and carry yellow flowers in loose spikes. The flowers are approximately 1-2 cm in diameter and appear from April to July. Each flower has five petals that are radially open. The plant naturally spreads seed and often forms semi-self-sowing populations.

Ideal location

Verbascum rotundifolium requires full sun. At least 7-8 hours of direct sunlight per day is essential. The plant tolerates hot, dry locations better than many other flowering plants. A south-facing location, possibly near walls or stones that reflect warmth, is ideal. Avoid shade and moist places.

Soil

The plant thrives in poor, well-draining soil. Sandy, gravelly, and loamy soils are all suitable. The plant tolerates even very nutrient-poor soils well, and often grows better in such soil than in rich, fertile soils. A neutral to slightly alkaline soil (pH 6.5-7.5) is ideal, though the plant is flexible. Ensure excellent drainage; prolonged water stagnation is harmful.

Watering

Verbascum rotundifolium is very drought-tolerant once established. Plant young plants in spring or fall and water carefully during the first growing period. Once well-rooted, water only occasionally, even during dry periods. The plant tolerates drought better than waterlogging. Rainwater is sufficient in normal climates. In extremely dry areas, deep watering once per month can contribute to larger flowers.

Pruning and maintenance

Minimal pruning required. Remove flower spikes after bloom to stimulate further blooming. Cut back dead plant parts in spring. The plant will naturally spread seeds and young plants will emerge next year. This may be desirable or undesirable, depending on your garden plans. Seed heads can be removed before they mature.

Maintenance calendar

March-April: Plant blooms; water carefully. May-June: Continuous bloom; minimize watering. July: Bloom slowly ends; reduce watering. August-October: Plant goes into rest; minimal water. November-February: Winter dormancy; no water needed.

Winter hardiness

Verbascum rotundifolium is winter-hardy to about -10 to -15 degrees Celsius, making it suitable for temperate climates. In very cold areas, the plant may die. In warm, Mediterranean climates, it is more frost-resistant. The plant sometimes grows as a biennial or short-lived perennial in cold regions. Snow cover can help.

Companion plants

Verbascum rotundifolium grows well with other drought-tolerant plants: santolina, lavender, nepeta, teucrium, and other Mediterranean herbs. Stonecrop, sedum, sempervivum, and other succulents form suitable ground covers. Avoid large, nutrient-demanding shrubs.

Closing

Verbascum rotundifolium is a brilliant choice for dry, sunny gardens. With its yellow flowers and distinctive round leaves, it brings Mediterranean charm to drought-tolerant soils. At gardenworld.app, we help you successfully integrate this drought-tolerant jewel. For more tips on drought-tolerant gardening, visit gardenworld.app.