Liquorice: Growing from Seed, Requirements and Harvesting the Root

In brief: Liquorice is a heat-loving perennial with a deep root. Before sowing, the seeds are soaked or their coat is scarified, and they are raised from March to April in warmth. In the bed it belongs in sunny, deep and well-drained soil. The root is harvested no earlier than the third to fourth year.

Liquorice (Glycyrrhiza glabra) is a perennial herb originating from the Mediterranean region and south-west Asia. It is known mainly for its sweet root, which is used in confectionery, but it is also grown as an interesting, richly leaved perennial. No other species in a bed looks like it: slender pinnate leaves and upright stems form an airy shrub.

In our climate growing liquorice is possible, but it requires warmth, sun and patience. The roots need several years to mature. If you are looking for a quick reward, liquorice is not ideal, but if you have sunny, deep soil and an appetite for an interesting plant, it is worth trying.

Requirements of liquorice

Liquorice spreads by rhizomes and underground runners, so give it a separate place. In a bed it pays to plant it with a root barrier or in a deep container, so that it does not spread to the surrounding beds.

Sowing and raising seedlings

Liquorice seeds have a hard coat. For them to germinate, it is good to scarify it or to soak the seeds in lukewarm water for a day or two before sowing. Some growers lightly scarify the coat with fine sandpaper.

1. In March to April prepare trays with well-drained substrate.
2. After soaking, sow the seeds to a depth of about 1 cm.
3. Place the trays in warmth, around 20–25 °C, and keep the substrate slightly moist.
4. After germination, thin out the seedlings and, once they have formed several leaves, prick them out into deeper pots.
5. Plant in the bed after the last frosts have gone, no earlier than the second half of May, after hardening off.

Germination is uneven and may take several weeks, so with patience we do not re-sow prematurely. Another option is propagation by root runners, which are divided in spring.

Soil and position

Choose the warmest spot in the garden, ideally in front of a south-facing wall or fence. The soil should be at least 40–50 cm deep, loose and well-drained. Loosen heavy clay soil with sand and compost. Liquorice does not tolerate permanent waterlogging; the roots would rot.

Before planting, dig the bed deeply, remove weeds and the roots of perennial weeds. Plant young plants at a spacing of 50–60 cm and water them after planting. In the first year liquorice is more sensitive; in later years it grows more independently.

Watering and feeding

In the first year water regularly so that the plants root. Later liquorice copes with dry spells thanks to its deep roots; only in long drought water generously. Feeding with compost once in spring is enough; do not overdo the nitrogen. Keep mulch around the plants; it limits weeds and drying out.

Care during the year and overwintering

In autumn cut back the dead above-ground parts. In mild locations the perennial overwinters without protection; in colder areas cover the base with evergreen branches or leaf mould. In spring the plant shoots later than most perennials, so do not consider it frozen until May has passed. If it spreads too much, cut off the runners with a spade.

Liquorice growing calendar

Propagation by runners and division

Liquorice can also be propagated vegetatively. In spring, before it shoots, use a spade to separate from the edge of the clump a runner with roots and buds and plant it straight away in a new place at the same depth as before. Water after planting and keep it moist for the first weeks. Plants obtained this way establish faster than seedlings from seed and reach harvest size sooner.

Diseases and pests

Liquorice tends to be fairly healthy. The biggest problem is root rot in heavy and waterlogged soil, so do not plant in waterlogged places. Watch out for slugs on young plants. Healthy plants resist better, so provide them with sun and well-drained soil. Remove affected parts and do not compost them.

Most common mistakes

• Soil that is too heavy. The roots rot or stay short.
• Shade and cold. The plant grows slowly and weakens.
• Unsuitable place. The spreading of runners around the garden is hard to stop.
• Early harvest. Young roots are thin and have no value.
• Watering in winter. Permanently damp soil destroys the roots.

Harvesting the root

Liquorice roots usually reach harvest size in the third to fourth year. They are harvested in autumn after the foliage has died back. Carefully dig the plant up with a spade or digging fork, because the roots go deep and break easily. Clean the root, wash it and leave it to dry in an airy shady place. Leave part of the roots in the ground so that the plant regenerates.

If you use the root in the kitchen or as a flavouring, stick to small amounts. Larger amounts of liquorice should not be consumed over the long term, especially with high blood pressure, in pregnancy or when taking medication. In such cases consult a doctor.

Liquorice as an ornamental plant

Besides the root, liquorice is also interesting in appearance. It has pinnate leaves and a pale spike-like inflorescence, which appears in summer in the leaf axils and resembles tiny pea-family flowers. It suits a herb or Mediterranean bed with sage, lavender and thyme. In a pot or on a patio its airy shape stands out. But remember the deep roots and runners, which make the plant a problem in small containers.

Frequently asked questions

How long does it take for liquorice to grow to harvest size?

The roots are usually harvested after three to four years. Beware, the roots are deep, so dig them up carefully.

Does liquorice overwinter in our climate?

In mild locations mostly yes; in colder areas cover it for the winter with evergreen branches or compost.

How should liquorice be sown?

Soak the seeds or scarify their coat before sowing, sow them into trays in March to April at 20–25 °C and, after hardening off, plant out after the frosts.

Can liquorice grow in a flower pot?

Only in deep large containers. The roots go deep and the plant spreads, so a bed is more suitable.

Why is liquorice slow to shoot in spring?

It shoots later than most perennials. Wait until May before writing it off; the shoots often appear later.

Sources

• Liquorice – Wikipedia
• Pea family – Wikipedia

Updated: 5 October 2026