Horseradish

Sun

Full sun to partial shade; full sun usually produces the best roots.

Water

Water deeply during dry spells, keeping the root zone evenly moist but never waterlogged.

Soil

Deep, fertile, well-drained soil, preferably a loose loam. Stony or compacted soil produces forked roots.

Height

2-3 ft (0.6-0.9 m), with flower stems sometimes reaching 4 ft (1.2 m)

Spread

2-3 ft (0.6-0.9 m) per clump; roots can spread farther over time

Flowers

Small white flowers in loose clusters in late spring to early summer; flowering can be sparse.

Foliage

Large, upright, glossy green leaves with prominent veins, wavy edges and coarse teeth; dies back in cold winters.

Growth

Fast

Care needed

Medium

• Pollinators
• Cold hardy
• Low allergen
• Edible

Northern hemisphere months. In Australia, shift them by six.

Difficulty

Easy

Toughness

Very tough

Pick your zone, country, light and whether you have pets.

1. Planting day

   1 ft (0.3 m)

2. After 1 year

   1.7 ft (0.53 m)

3. After 2 years

   2.5 ft (0.75 m)

   full size

About 2 years to full size.

From a typical nursery size, at an average rate for this kind of plant. A rule of thumb, not a forecast.

Cats and dogs

Mildly toxic: may upset a stomach

In the garden

Spreads vigorously: plan to contain it.

Growth rate

Fast

• Plant root cuttings in early spring in deeply loosened soil.
• Mix in mature compost before planting; avoid heavy nitrogen feeding, which encourages leaves rather than roots.
• Water during dry weather to support root growth and reduce toughness.
• Mulch around plants to conserve moisture and suppress weeds.
• Use a large container or a dedicated bed, and remove unwanted shoots with their roots.

Pruning. Remove flower stems as they appear if root production is your priority. Cut dead foliage to ground level after autumn dieback, and remove badly damaged leaves during the growing season.

Lift thick roots in late autumn or winter once the leaves die back, usually after one full growing season; roots about a finger's thickness or larger are useful for grating. Loosen the soil deeply with a fork and lift carefully, collecting fragments to prevent unwanted regrowth.

Early spring

Prepare a contained bed or large container with compost and plant root cuttings.

Late spring

Weed around young plants, mulch the soil and remove unwanted shoots.

Early summer

Remove flower stems if you want to concentrate growth on the roots.

Summer

Water deeply in dry spells and check leaves for flea beetles and caterpillars.

Late autumn

After foliage dies back, cut it down and lift roots for the kitchen.

Winter

Harvest when soil is workable, and store spare roots cool and moist without allowing them to freeze.

• Place in a dedicated corner of a kitchen garden where persistent roots will not disturb crop rotations.
• Grow in a large, deep container near the kitchen for accessible harvesting and easier control.
• Use its bold leaves behind lower herbs such as chives and thyme in an edible border.
• Include in a spacious homestead or perennial food garden, separated from delicate, slow-growing crops.

Garden styles it suits: Potager (kitchen garden), Cottage garden, Farmhouse, Edible landscape, Homestead and Sensory garden.

Plant it with: Chives, Thyme, Calendula and Nasturtium.

Wildlife: Flowers provide nectar and pollen for visiting insects. As a cabbage-family plant, it can also feed cabbage white butterfly caterpillars.

• Flea beetles make small holes in young leaves: protect new growth with fine insect mesh and keep plants watered.
• Cabbage caterpillars chew leaves: inspect leaf undersides and hand-pick caterpillars, or protect plants with insect mesh.
• Waterlogged soil causes root decay: improve drainage or grow in a raised bed or container.
• Unwanted regrowth follows harvesting or digging: remove root fragments carefully and repeatedly dig out new shoots; do not cultivate through an established patch.

The roots are edible for people in small condiment quantities, but their mustard oils can irritate skin, eyes and the digestive tract; large amounts can cause significant stomach upset. Roots and leaves should not be fed to cats, dogs or horses, as chewing releases irritating compounds that can cause digestive upset, particularly in quantity.

Where it spreads. Spreads aggressively from persistent roots and discarded root fragments. It escapes cultivation in parts of the northern United States and southern Canada and can become a persistent garden escape in the United Kingdom and temperate southeastern Australia; keep it away from natural areas and do not dump roots with garden waste.

• Broad-leaved dock (Rumex obtusifolius)

  Dock usually has broader, heart-based leaves and produces tall spikes of small green flowers followed by brown seeds. Horseradish has elongated, coarsely toothed leaves and white, four-petalled flowers.

• Comfrey (Symphytum officinale)

  Comfrey leaves and stems are conspicuously rough and hairy, and its flowers are hanging bells. Horseradish leaves are mostly hairless, with small white flowers in open clusters.

The botanical epithet rusticana means 'of the countryside' or 'rustic'.

Propagation. Propagate by pencil-thick root cuttings in early spring. Set cuttings about 8-12 in (20-30 cm) long at an angle, with the upper end roughly 2 in (5 cm) below the soil surface; space plants 18-24 in (45-60 cm) apart.

Accepted botanical name

Armoracia rusticana

In the US and Canada

Introduced in Canada and the lower 48 states.

Native range

South European Russi and Ukraine.

Measured

Soil pH 5.5 to 6.5. Average height 100 cm.

Sources: GBIF (CC BY 4.0), USDA PLANTS and Trefle (CC BY 4.0). The care and design notes are LandscapeGPT's own.