Tarwi
Lupinus mutabilis
Lupinus mutabilis, commonly known as Tarwi, is a unique legume native to the Andes, valued for its nutritious seeds and beautiful flowers. This plant is not only visually appealing but also enriches the soil, making it a favorite among gardeners looking for both beauty and functionality.
Everything it needs
9 essentials at a glance
Watering
Lupinus mutabilis, or Tarwi, prefers well-drained soil and should be watered moderately.
Water every 1-2 weeks, allowing the top inch of soil to dry out between waterings. During hot summer months, increase frequency to once a week. Signs of over-watering include yellowing leaves and root rot, while under-watering may cause wilting and leaf drop.
Light
Tarwi thrives in full sun, requiring at least 6-8 hours of direct sunlight daily.
Ideal placement includes south or west-facing gardens. It can tolerate partial shade but may result in leggy growth and fewer flowers. Ensure it receives adequate light for optimal growth and flowering.
Soil
The ideal soil for Tarwi is sandy or loamy with good drainage, with a pH range of 6.0 to 7.5.
A recommended potting mix includes a blend of potting soil, sand, and perlite to enhance drainage. Avoid heavy clay soils that retain water, as this can lead to root issues.
Humidity
Tarwi prefers moderate humidity levels, around 40-60%.
To increase humidity, consider misting the leaves or placing a humidifier nearby. Conversely, if humidity is too high, ensure good air circulation to prevent fungal diseases. Signs of humidity stress include browning leaf edges and stunted growth.
Temperature
The ideal temperature range for Tarwi is between 60-75°F (15-24°C).
It is hardy in USDA zones 9-11 and can tolerate light frost. However, prolonged exposure to temperatures below 50°F (10°C) can hinder growth. During summer, ensure it is not exposed to extreme heat above 85°F (29°C).
Fertilizing
Use a balanced fertilizer with an NPK ratio of 10-10-10, applying every 4-6 weeks during the growing season.
In fall, reduce fertilization as the plant enters dormancy. Signs of nutrient deficiency include yellowing leaves (nitrogen), poor flowering (phosphorus), and stunted growth (potassium).
Pruning
Prune Tarwi in early spring to remove dead or damaged stems and to shape the plant.
Use clean, sharp pruning shears to make cuts just above a leaf node. Deadheading spent flowers encourages more blooms and prevents self-seeding. Regularly check for any unwanted growth to maintain its shape.
Repotting
Repot Tarwi every 2-3 years or when it becomes root-bound, indicated by roots growing out of the drainage holes.
Choose a pot 1-2 inches larger in diameter. Carefully remove the plant from its pot, loosen the roots, and place it in fresh potting mix. Water thoroughly after repotting to settle the soil.
Propagation
Tarwi can be propagated through seeds or division.
For seed propagation, soak seeds in water for 24 hours before planting in well-drained soil. Sow seeds 1 inch deep in spring after the last frost. For division, carefully separate established plants in early spring or fall, ensuring each division has roots and shoots. Replant immediately.
When it's unhappy
Yellow leaves
Why it happens
This can be caused by over-watering or nutrient deficiency.
How to fix it
Check the soil moisture and adjust watering frequency. If nutrient deficiency is suspected, apply a balanced fertilizer.
Wilting leaves
Why it happens
Under-watering or extreme heat can lead to wilting.
How to fix it
Increase watering frequency, especially during hot weather, and ensure the plant is in a suitable location with adequate light.
Root rot
Why it happens
Excessive moisture in the soil can lead to root rot.
How to fix it
Ensure proper drainage and reduce watering frequency. If root rot occurs, remove affected roots and repot in fresh soil.
Powdery mildew
Why it happens
High humidity and poor air circulation can cause powdery mildew.
How to fix it
Improve air circulation around the plant and reduce humidity. Treat with a fungicide if necessary.
Leggy growth
Why it happens
Insufficient light can result in leggy growth.
How to fix it
Move the plant to a brighter location to ensure it receives adequate sunlight.
Care through the year
Spring
In spring, prune any dead or damaged stems and begin fertilizing every 4-6 weeks to support new growth. Monitor for pests as the weather warms.
Summer
During summer, ensure consistent watering, especially in hot weather. Provide some afternoon shade if temperatures exceed 85°F (29°C) to prevent stress.
Fall
In fall, reduce watering as the plant prepares for dormancy. Stop fertilizing and consider mulching to protect roots from cooler temperatures.
Winter
In winter, protect Tarwi from frost and cold winds. If grown indoors, reduce watering and keep it in a cool, bright location.
Toxicity & Safety
Tarwi is generally considered non-toxic to pets and children. However, ingestion of large quantities may cause mild gastrointestinal upset. It is advisable to keep the plant out of reach of pets to prevent any potential issues.
Good to know
How often should I water my Tarwi plant?
Water your Tarwi plant every 1-2 weeks, allowing the top inch of soil to dry out between waterings. Increase frequency during hot months.
What type of soil is best for Tarwi?
Tarwi thrives in sandy or loamy soil with good drainage and a pH range of 6.0 to 7.5. A mix of potting soil, sand, and perlite is ideal.
Why are my Tarwi leaves turning yellow?
Yellow leaves can indicate over-watering or a nutrient deficiency. Check soil moisture and consider fertilizing if needed.
Can Tarwi tolerate frost?
Tarwi can tolerate light frost but should be protected from prolonged exposure to temperatures below 50°F (10°C) to ensure healthy growth.
How do I propagate Tarwi?
Tarwi can be propagated through seeds or division. Soak seeds before planting or carefully divide established plants in early spring or fall.
What is the ideal temperature for growing Tarwi?
Tarwi prefers temperatures between 60-75°F (15-24°C) and is best suited for USDA zones 9-11.
How do I prevent powdery mildew on my Tarwi?
To prevent powdery mildew, ensure good air circulation, avoid overcrowding, and reduce humidity around the plant.
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