<em>Lysimachia</em>: planting, care and propagation

Description and botany

Loosestrifes (Lysimachia in Latin) are hardy herbaceous perennials of the Primulaceae family. All appreciate particularly fresh to wet mediums.

Origin of name Lysimachia is uncertain but probably Greek. It may refer to name of a king or a physician in antiquity.

English speakers call lysimaque jaune yellow loosestrife, which corresponds to yellow loosestrife. Indeed, resemblance with some wetland species cannot be denied. Some have very floriferous upright stems, one yellow — common loosestrife — and one pink — purple loosestrife.

Native to temperate regions of northern hemisphere, mainly Europe and Asia, they are very hardy. Hardiness ranges from -7°C to -30°C. With more than 150 different species of loosestrifes, they show great diversity of flowers, colours, habit and leaves.

Loosestrifes occur with upright, tufted or creeping habit with white, yellow or pink flowers. They flower between June and September. Note white flowering of Chinese loosestrife while Beaujolais loosestrife blooms wine-coloured. Flowers can be star-shaped, solitary or grouped in whorls, spikes or clusters. Their flowers are valued by pollinating insects such as butterflies and other nectar feeders. Largest loosestrifes reach up to 1.20 metres like common loosestrife. Smallest are under 10 cm tall with a mat-forming habit such as Lysimachia nummularia, also called moneywort. Taller species are perfect for creating a bright back to a border, while mat-forming species make an ideal groundcover for wet soils. Upright species can also be used in cut-flower arrangements.

Spotted loosestrife

Leaves of loosestrifes are deciduous or evergreen, opposite or whorled depending on species. Leaves vary widely in shape and size. They can be soft green, golden, silver, variegated or purple. Ephemeral or willow-leaved loosestrife (Lysimachia ephemerum) is perhaps one of most ornamental with its silvery foliage and white flowers.

All prefer rich soils and above all consistently fresh to wet conditions. They particularly appreciate pond edges, woodland edges or wet meadows. Regarding soil pH, they tolerate almost all pH levels and even heath soils.

Used as an ornamental plant in gardens, they suit natural gardens as well as landscaped or contemporary gardens.

Easy to grow, some loosestrifes can nevertheless become invasive. They develop a rhizomatous rootstock that spreads quickly and is difficult to remove. Indeed, spotted loosestrife, Lysimachia punctata, has spread so well in France that it is considered naturalized.

As for common loosestrife, Lysimachia vulgaris, very invasive, it is declared invasive in some countries.

Botanical species of loosestrifes

• Common loosestrife, great loosestrife or chasse-bosse, Lysimachia vulgaris

This botanical species is probably best suited to natural gardens and pond edges. Vigorous and with rapid growth, it quickly colonises space, creates an attractive mass effect and stabilises pond banks. It flowers bright yellow on the upper third of its tall upright stems. Small cup-shaped flowers measure only 2 cm across but flowering is long and abundant. This species is particularly invasive. When planting, use an anti-rhizome barrier (thick, resistant polypropylene film) to limit spread.

• Spotted loosestrife, Lysimachia punctata

This robust perennial is recognised by its clusters of bright yellow flowers arranged in successive tiers. Undemanding, it tolerates all exposures provided soil remains fresh year-round. Like common loosestrife, this species spreads by suckers in heavy, wet soils.

Our favourite Lysimachia varieties

Lysimachia punctata Alexander - Loosestrife

Perennial and robust, Lysimachia punctata 'Alexander' has light green foliage variegated with pinkish-white.

• Flowering time August, September
• Height at maturity 70 cm

See the product sheet

Lysimachia clethroides - Loosestrife

This Chinese Lysimachia, hardy to below -15°C, is highly prized for its white flowers on curved spikes.

• Flowering time August, September
• Height at maturity 70 cm

See the product sheet

Lysimachia fortunei - Loosestrife

This robust perennial enchants with delicate upright white inflorescences above the foliage. Its foliage turns red-orange in autumn.

• Flowering time August, September
• Height at maturity 80 cm

See the product sheet

Lysimachia nummularia Goldilocks - Creeping Jenny

Lysimachia nummularia 'Goldilocks', also known as moneywort, charms with its fine golden foliage. Creeping, it is ideal as groundcover both in the ground and in a pot.

• Flowering time July to September
• Height at maturity 8 cm

See the product sheet

Lysimachia atropurpurea Beaujolais - Loosestrife

Lysimachia atropurpurea 'Beaujolais' stands out for its wine-coloured spike flowers. They appear above grey-green foliage that turns purple in autumn.

• Flowering time July, August
• Height at maturity 80 cm

See the product sheet

Planting Lysimachia

When to plant loosestrife?

Plant loosestrife preferably in autumn or spring. In autumn, plants have time to settle in over winter: this wetter period favours establishment.

Where to plant loosestrife?

Loosestrife are best planted in full sun, although some varieties tolerate partial shade. They are suitable for woodland edges, beside ponds, in a wet meadow or in a cool, sunny border.

They prefer a rich soil that stays cool to moist. If ground is rather dry, loosestrife will remain smaller and more compact. They tolerate humus-bearing to clay soils, even heavy soils. They accept soil with neutral to slightly acidic or alkaline pH.

Hardy from -7°C to -25°C depending on variety, they can be planted almost anywhere in France.

They suit contemporary, natural or English gardens equally well.

Planting loosestrife in the ground

Depending on size of loosestrife chosen, plant 3 to 5 plants per m².

1. For rootballed loosestrife, immerse rootballs while preparing ground.
2. Dig a hole three times size of rootball or five times size of your rootstock.
3. Some loosestrife can be invasive, especially beside ponds where moisture is constant year-round. To avoid this, fit a rootstock barrier.
4. If soil is poor, mix garden soil with 50% compost or potting compost.
5. Place rootball level with soil or place rootstocks 25 cm deep.
6. Backfill with soil mix.
7. Water thoroughly.
8. Mulch around plant to reduce watering and keep soil cool for longer.

Water for first years after planting.

Planting loosestrife in a pot

Since loosestrife prefer rich, cool to moist conditions, prepare a rich substrate that retains water well. For this, choose a potting compost for flowering plants to which add a few handfuls of sand. In small proportion, sand helps water retention.

Choose a pot large enough so that rootstocks can be placed in a hole 25 cm deep. Loosestrife quickly grow to fill the entire pot.

During first years after establishment, take care to water well. Thereafter, water only to keep soil consistently cool to moist year-round. Soil should not dry out between waterings.

Planted in sun or partial shade, in rich, fresh to moist soil, the Chinese loosestrife is an easy plant that grows steadily.

Caring for your Lysimachia

Easy to grow, loosestrifes require little maintenance and are not very susceptible to diseases. They can be cultivated by novice gardeners.

Lysimachia-atropurpurea-Beaujolais

At end of winter, start by cutting back all dead stems of loosestrife to ground level if still present. New shoots of the year can then develop freely. Slugs can attack young shoots. Protect shoots from attack. For more information: 7 effective ways to combat slugs naturally.

At resumption of growth in spring, top-dress with compost to feed your plant. For loosestrifes with upright habit, if stems are too tall or not bushy enough, pinch them to reduce height and encourage branching.

As flowering progresses, remove faded flowers or cut spent stems back to ground level. This prevents plant from using its energy to produce seeds rather than to flower. By preventing seed formation you also prevent plant from self-seeding and ending up with new plants throughout your garden.

In summer, water and mulch the base of your loosestrifes to keep soil cool and moist. Maintaining moisture is essential for good flowering. Mulching reduces need for watering. Soil must never dry out between waterings because loosestrifes do not tolerate drought.

In winter, cut back deciduous loosestrifes to ground level when they have lost ornamental interest. This pruning takes place between January and March.

To maintain vigour of your plant, divide rootstock into several divisions every 5 to 6 years. For very vigorous plants, contain spread by removing invasive parts with a spade.

Caring for loosestrife in a pot

To care for loosestrife in a pot, provide the following additional maintenance:

• Repot every year at start of spring using potting compost for flowering plants.
• From April until end of flowering, apply liquid fertiliser for flowering plants with your waterings.
• Water so that soil never dries out completely.
• Mulch your pot to retain moisture as long as possible and reduce need for watering.

Propagating your Lysimachia

Dividing Lysimachia

Even though propagation by cuttings and sowing can multiply Lysimachia, division has the advantage of being faster and produces the same variety as the parent plant. Division is possible if specimen is well established. It is carried out in spring or autumn.

To divide Lysimachia, follow these steps.

1. Using a fork or spade, lift the Lysimachia rootstock completely.
2. With a spade, divide the rootstock into several pieces.
3. Plant each piece about 25 cm deep in a hole five times wider than the rootstock.
4. Fill the hole with garden soil mixed with 50% compost or potting compost.
5. Water thoroughly.
6. Mulch to conserve soil moisture and reduce watering.

Sowing Lysimachia

Sowing is possible but can take a long time. Proceed as follows :

1. Sow in seed compost between February and July.
2. Keep compost moist with regular watering and maintain a humid atmosphere by covering with a plastic bag. Temperature should be kept between 18°C and 25°C. Germination varies between 1 and 4 months.
3. When young plants are large enough for 8 cm pots, pot them on.
4. Harden off young plants to outdoor conditions in partial shade when temperatures are mild.
5. Plant in sun or partial shade in rich, loose and moist soil.

Good to know: Lysimachia sold as seed are sometimes short-lived cultivars (1–2 years). They are grown almost like annuals.

Companion planting with Lysimachia

We often plant lysimachias in partial shade to ensure constant freshness. Create a partial-shade border with lysimachias; pair them with alchemillas, hostas, astilbes, aruncus or ferns.

Pair Lysimachia punctata from front to back in the border: Astilbe simplicifolia Darwin’s Snow Sprite (first photo on right), Hosta Paul’s Glory (second photo on right), then the white spikes of Aruncus dioicus sylvestris (third photo on right) and purple foliage of Berberis thunbergii atropurpurea.

In a sunny position, lysimachias harmonise with rhubarb, garden angelica, oriental poppies and foxgloves.

For pond edges, lysimachias pair wonderfully with moisture-loving plants: purple loosestrifes, marsh mallows, meadowsweets, filipendulas, tiered primulas, horsetails, geraniums such as Geranium psilostemon or even a bush such as Flamingo willow ‘Hakuro Nishiki’.

As for lysimachias with a creeping habit such as Lysimachia nummularia Goldilocks, they create an ideal groundcover in a cool rockery or at pond margins. In a pot, create a graphic floral composition with annuals such as blue lobelias, mauve and violet petunias or the purple foliage of ipomoeas.

Golden, creeping foliage of Lysimachia nummularia Goldilocks with blue flowers of lobelias (Lobelia Hot Royal Blue) and purple foliage of Ipomoea Illusion Midnight.

→ Discover other ideas for pairing with Lysimachias in our care sheet.

Did you know?

Lysimachias are also known for their medicinal and dyeing uses.

Common loosestrife, also called greater loosestrife (Lysimachia vulgaris), is reputed for its wound-healing and astringent properties. This earned it the name chasse-bosse. As for yellow flowers of lysimachias, they are used to produce a yellow dye, while their roots yield a brown dye.