Thermopsis Plant Growing & Care Guide for Gardeners
Article by Dean Ravenscroft, Ph.D. - Updated 27th Oct 2023
In this Gardener's HQ guide, we'll explore cultivating Thermopsis plants in your garden, indoor spaces, and other settings.
- Plant Characteristics: Thermopsis plants have bright yellow flowers that resemble those of the pea plant. This genus's vibrant blooms can add a cheerful pop of color to a garden.
- Ideal Growing Conditions: Plants will thrive in full sun and well-draining soil. They will appreciate consistent moisture, but are able to tolerate periods of drought.
- General Care: Deadhead spent flowers to promote new blooms. Mulching around the base can help retain moisture and suppress weeds.
- Tips for New Gardeners: False lupine has a resilient nature that makes it suitable for gardeners of all experience levels. Protect from excessive moisture, as this can lead to root rot.
Goldenbanner, Carolina Lupine, and Aaron's Rod: Cultivation & Garden Use
Thermopsis are hardy perennials. They range from 30 cm to 1.5 m (1 to 5 feet) in height.
Plants bloom from late spring to summer, when they carry yellow flowers resembling those of peas.
Some of the common names for Thermopsis include goldenbaner, Aaron's rod, False Lupine, and Carolina Lupine.
Thermopsis montana by peganum.
How to Grow Thermopsis Species such as Goldenbanners and Aaron's rod
The seeds of Thermopsis plants should be sown outdoors just before the last frost of spring, or late on in autumn. Once sown, lightly cover the seeds.
Ideally they should be grown in a sunny or partially shaded area of the garden. This location should have a gritty soil, with pH 5.5 to 7.
If starting off indoors, then sow Goldenbanners, Aaron's rod, and similar seeds into peat pots. Do this about seven weeks before the last frost is expected.
The seeds should first be chipped. Then they need to be imbibed by soaking in warm water for a day.
It should take from two weeks to a month for them to germinate. Once established, transplant the young plants outdoors following the last frost of spring. Space out at about 50 to 60 cm apart (20 to 24 inches).
Caring for Thermopsis
It is easy to care for Thermopsis plant species - taller varieties should be staked in windy areas.
Remove the flowering stalks once they have finished flowering to allow for a second bloom. Cut back to the ground in the autumn.
If you require more plants, it is probably best to grow from seeds as the plants have a delicate taproot. That said, you can attempt to propagate by division in the spring.
Common Types of Thermopsis
Some of the main species of this plant are Thermopsis lanceolata, Thermopsis montana, Thermopsis villosa, Thermopsis caroliniana, and Thermopsis rhombifolia.
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Thermopsis Growing and Care Guide
- Common Names: Goldenbanner, Carolina lupine, Golden bean, wet tooth, False lupine, Mountain thermopsis.
- Life Cycle: Hardy perennial.
- Height: 12 to 60 inches (30—150 cm).
- Native: North America, East Asia.
- Growing Region: Zones 3 to 9.
- Flowers: Late spring through to summer.
- Flower Details: Yellow. Pea-like. Terminal racemes. Erect stalks. Similar to lupines.
- Fruit: Legume pod. Villous (shaggy).
- Foliage: Herbaceous. Clump forming. Greyish-green. Compound. Oval leaflets.
- Sow Outside: Cover seed. Start of spring - before the last light frost, or towards the end of autumn.
- Sow Inside: : Germination time: two to four weeks. Temperature: 70°F (21°C). First chip seeds, soak for a day in warm water, then sow in peat pots. Seven or eight weeks before the expected last frost. Transplant outdoors following the last frost. Space at 18 to 24 inches (45—60 cm).
- Requirements and care: Full sunlight or light shade in hot areas. Good drainage. Acidic to neutral soil pH 5.5 to 7. Gritty soil for best results, but tolerant of most soil types. Can survive in dry soils. Deadhead to promote second bloom. Provide support. Cut back to the ground in autumn. Long taproots make it difficult to transplant. Propagate: by division in the spring.
- Family: Fabaceae.
- Closely Related Species: Beans, Peas, and other Legumes.
- Miscellaneous: Toxic if ingested. Traditionally used by Native Americans to produce yellow dye and as an infusion to treat stomach disorders, especially in horses.
Common Questions
How many members does the Thermopsis genus have?
The Thermopsis genus, also known as False Lupine, consists of around 20 species.
Do members of Thermopsis make a good garden or landscaping plant?
Yes, Thermopsis species, with their vibrant flowers and attractive foliage, make a great addition to meadows, borders, or naturalized gardens.
Which Thermopsis species are most frequently grown by gardeners?
The most frequently grown species is Thermopsis villosa, also known as Carolina lupine or Aaron's rod.
Are members of the Thermopsis plant genus fragrant?
Thermopsis species are not typically known for fragrance, but for their vibrant yellow flowers and lupine-like appearance.
What is the perfect location to grow Thermopsis?
Thermopsis prefers full sun and well-drained soil. It's a great choice for meadows, sunny borders, or native plant gardens.
Is Thermopsis invasive in the USA, if so in which states?
Currently, Thermopsis is not listed as invasive in the USA. Always check local guidelines for the most accurate information.
How do I remove Thermopsis plants from my garden?
To remove Thermopsis, uproot the entire plant including the root system to prevent regrowth.
Summary
Thermopsis plants belong to the Fabaceae family. It consists of about 20 species of perennial herbaceous plants native to North America and East Asia. These plants resemble lupines and have pea-like flowers.
Generally, Thermopsis plants thrive in full sun with well-drained soil. They can be sown in either spring or autumn. It's a hardy plant and can withstand some drought once established.
I hope that you enjoyed this guide on how to grow Thermopsis plants. You may also enjoy the following Gardener's HQ growing guides: How to grow Sweetpea and Dolichos plants.
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