Lythrum Plant Growing & Care Guide for Gardeners
Article by Dean Ravenscroft, Ph.D. - Updated 30th Oct 2023
In this Gardener's HQ guide, we'll explore cultivating Lythrum plants in your garden, indoor spaces, and other settings.
- Plant Characteristics: Members of the Lythrum genus display vibrant purple-pink flowers that attract pollinators. These plants can bring a splash of color to a wild garden.
- Ideal Growing Conditions: These plants thrive in full sun to partial shade and prefer moist soils. Wetlands and pond margins are natural habitats.
- General Care: Regular watering is crucial, especially in drier climates. Prune spent flowers to promote further blooming.
- Tips for New Gardeners: Purple loosestrife is adaptive but can be invasive in many areas; check your local regulations before growing this plant in your garden. If you choose to grow it then be sure to monitor its spread in the garden (in a contained area), and don't allow them to overwhelm native species.
Loosestrife, and Purple Willow Herb: Cultivation & Garden Use
Lythrum plants are hardy perennials. They can reach an height of 150 cm (5 feet).
Be aware that they are an invasive species in many areas in Northern America, and growing them is banned in the garden in many areas. This is to help with control of these plants in native wetland areas.
Lythrum salicaria by Ettore Balocchi.
In areas where it can be grown non-invasively, it makes a useful pond edge plant. When in bloom it carries purple-red flowers.
Lythrum alatum - Winged Loosestrife by bob in swamp.
Common Lythrum Species Photographs and Plant Identification
Lythrum alatum
Lythrum alatum (Winged Loosestrife), photograph by Frank Mayfield; CC.
Lythrum hyssopifolia
Lythrum hyssopifolia (Hyssop Loosestrife / Grass-poly), photograph by Doug Beckers; CC.
Lythrum salicaria
Lythrum salicaria (Purple Loosestrife / Spiked Loosestrife), picture by Andreas Rockstein; CC.
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Lythrum Plant Growing and Care Guide
Common Names: Loosestrife, Purple Loosetrife, Purple Willow Herb, False grass-poly, Red Sally.Life Cycle: Hardy perennial.
Height: 24 to 60 inches (60 to 150 cm).
Native: Asia. Australasia. Africa. Europe.
Family: Lythraceae.
Growing Region: Zones 3 to 9.
Flowers: Summer through to early autumn.
Flower Details: Pink, purple-red. Spikes. Six petals.
Foliage: Herbaceous. Lance-shaped. Oblong. Broad. Downy.
Sow Outside: Cover seed. Start of spring - before the last frost, or towards the end of autumn. Spacing 18 to 36 inches (45 to 90 cm).
Sow Inside: Germination time: one week to one month. Temperature: 65 to 70°F (18 to 21°C). Seven or eight weeks in advance. Transplant outdoors following the last frost.
Requirements and care: Full sunlight or partial shade. Soil pH 5.0 to 7.0. Wet to moist soil. Deadhead to prevent seed set and to keep tidy. Divide every coupl of years to aid in control. Propagate: Self seeds readily. Or by dividing at the beginning of spring.
Miscellaneous: Can grow incredibly invasively, and growing it is banned in many areas; the plant is usually controlled by the use of beetles. Lythrum is also a food plant for many Lepidoptera members including the Emperor moth and the V-pug. Used to treat diarrhea and dysentery.
Common Questions
How many members does the Lythrum genus have?
The Lythrum genus has about 30 to 40 species. This includes the Purple Loosestrife, a well-known garden plant.
Do members of Lythrum make a good garden or landscaping plant?
Lythrum can be an attractive garden plant with its tall spikes of pink-purple flowers. However, some species like Lythrum salicaria can be highly invasive. Only consider it in areas where the plant is a native, and growing it is not an issue.
Which Lythrum species are most frequently grown by gardeners?
The most frequently grown species is probably Lythrum salicaria (Purple Loosestrife). But it is very important to note that it is invasive in many regions of the world, and is especially an issue in wetland areas of the USA.
Are members of the Lythrum plant genus fragrant?
While Lythrum species aren't known for their fragrance, the bright, attractive flowers of species like Lythrum salicaria are a magnet for butterflies.
What location do Lythrum plants grow in?
Lythrum prefers full sun and moist soil. Lythrum salicaria particularly thrives near water, such as by ponds or streams.
Is Lythrum invasive in the USA, if so in which states?
Lythrum salicaria, or Purple Loosestrife, is considered invasive in most US states, particularly in the Northeast and Midwest where it is known to clog wetland habitats. Check your local regulations before considering growing this plant!
How do I remove Lythrum plants from my garden?
Controlling Lythrum Plant: You should dig up the entire plant, ensuring to remove all roots. In case of Lythrum salicaria, it may require a permit to interact due to its invasive status.
Summary
The Lythrum plant genus is a member of the Lythraceae family. The genus includes annual and perennial plants native to temperate parts of the world. Known for their tall, spiky flowers, these plants are often used in borders and waterside plantings.
Lythrum plants prefer to grow in full sun, and enjoy a well-drained, yet moist soil. Regular watering is necessary for best growth. Propagation can be done from seeds, or through division. This can be done in spring or fall.
I hope that you found this guide on how to identify Lythrum plants useful. You may also enjoy my gardening guides on how to grow Gloriosa-lily, Asclepias syriaca and Lima Bean plants.
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