Marrubium vulgare

Growing in Pots, Balconies & Indoors

White horehound is a hardy, sun-loving medicinal herb the grower confirms is not a houseplant but grows well in containers. Grow it in a sunny pot on a patio or balcony rather than indoors; a container also helps keep this ready self-seeder from spreading.

Quick Details

• Container Size: A medium pot, 5-15 L, for a 20-50 cm plant
• Indoor Suitability: Not an indoor plant – a hardy outdoor herb
• Best Spot: Full sun to part shade, outdoors
• Soil & Drainage: Free-draining mix; it is drought-tolerant and dislikes wet feet
• Watering in Pots: Average water; let the top dry between waterings

Indoors & On the Windowsill

• Not a houseplant: A tough Mediterranean herb that won’t thrive in a room; a very sunny sill might hold a young plant briefly, but it belongs outside.
• Windowsill: Too dim indoors for a sun-loving herb to stay compact.

On a Balcony or Patio

• Light & seeding: Give it the sunniest spot; deadhead before seed sets, as it self-seeds freely.
• Practicalities: Once established it is drought-tolerant – handy for a hot, dry corner; water when the surface dries.

Choosing the Pot, Soil & Long-Term Care

• Pot & drainage: A well-drained pot with strong drainage holes and no standing-water saucer to avoid root rot; terracotta breathes and dries faster, glazed or plastic holds moisture longer.
• Potting mix: A well-aerated, organic-rich potting mix – peat or coir blended with perlite or vermiculite, leaning free-draining.
• Feeding: Potted plants are fed more often than those in the ground, as watering steadily leaches nutrients from the mix – a light feed; herbs stay more aromatic on a lean diet.
• Repotting: Refresh the top of the mix and pot up about every couple of years, lightly trimming the root ball and top growth every year or two.

Bloom & Flower Guide

Quick Details

• Bloom Season: Summer into autumn
• Flower Appearance: Small white to pale flowers packed into dense whorls (clusters) around the square stems
• Edibility: A medicinal and aromatic herb; the leaves are the useful part, and the flowers are not treated as an edible flower

Detailed Blooming Overview

White horehound is a woolly, grey-green member of the mint family whose small flowers gather in tight whorls in the leaf axils, so the flowering stem looks like a series of bristly balls up the square stem. The blooms are modest but a good nectar source for bees. The plant is best known as the traditional source of horehound (from the leaves), used in old-fashioned cough remedies and candy.

Flower Characteristics

• Small two-lipped flowers, white to pale, easy to overlook individually.
• Densely clustered in whorls (verticillasters) around the stem, with hooked calyx teeth that later cling to fur and clothing.

Bloom Care & Thinning

• Pollination: Worked by bees drawn to the nectar.
• Managing the bloom: Cut back after flowering to keep the plant tidy and curb its free self-seeding.