Blackeyed Susan Vine
Thunbergia alata
Thunbergia alata, commonly known as the Blackeyed Susan Vine, is a vibrant climbing plant native to Africa. Its striking yellow and orange flowers attract pollinators, making it a favorite among gardeners looking to add color and life to their outdoor spaces.
Everything it needs
9 essentials at a glance
Watering
Thunbergia alata prefers consistently moist soil but should not be waterlogged.
Water when the top inch of soil feels dry, typically every 3-5 days during the growing season. In cooler months, reduce watering to every 7-10 days. Signs of over-watering include yellowing leaves and root rot, while under-watering leads to wilting and dry leaf edges.
Light
This plant thrives in full sun to partial shade, ideally receiving 6-8 hours of direct sunlight daily.
It can tolerate some shade but may produce fewer flowers. Ideal placements include south or west-facing areas, ensuring it has enough light to flourish.
Soil
Thunbergia alata prefers well-draining soil with a pH range of 6.0 to 7.0.
A mix of potting soil, compost, and perlite or sand is recommended to improve drainage. Ensure the pot has drainage holes to prevent water accumulation.
Humidity
This vine enjoys moderate to high humidity levels, ideally around 40-60%.
To increase humidity, mist the leaves regularly or place a humidifier nearby. Signs of low humidity stress include browning leaf tips and leaf drop.
Temperature
The ideal temperature range for Thunbergia alata is 65-85°F (18-29°C).
It is hardy in zones 9-11 and can tolerate brief periods of cooler temperatures but should be protected from frost. In extreme heat, provide some afternoon shade to prevent stress.
Fertilizing
Use a balanced fertilizer with an NPK ratio of 10-10-10 or 14-14-14 every 4-6 weeks during the growing season.
Reduce or stop fertilizing in fall and winter. Signs of nutrient deficiency include yellowing leaves, poor growth, and reduced flowering.
Pruning
Prune Thunbergia alata in early spring to promote bushier growth and remove any dead or damaged stems.
Use sharp, clean pruning shears to make clean cuts. Deadheading spent flowers encourages more blooms and should be done regularly throughout the growing season.
Repotting
Repot Thunbergia alata every 1-2 years or when the roots outgrow the pot.
Signs it needs repotting include roots growing out of the drainage holes and stunted growth. Choose a pot 1-2 inches larger in diameter, and follow up with fresh potting mix.
Propagation
Thunbergia alata can be propagated through stem cuttings or seeds.
For stem cuttings, take 4-6 inch cuttings from healthy stems, remove lower leaves, and place them in moist potting mix. Keep the cuttings in a warm, humid environment until roots develop, usually within 2-4 weeks. For seeds, sow them in spring after the last frost, covering lightly with soil.
When it's unhappy
Yellow leaves
Why it happens
Often caused by over-watering or nutrient deficiency.
How to fix it
Check the soil moisture and adjust watering accordingly. Fertilize if nutrient deficiency is suspected.
Wilting leaves
Why it happens
Usually a sign of under-watering or extreme heat.
How to fix it
Increase watering frequency and provide some shade during the hottest part of the day.
Root rot
Why it happens
Caused by overly wet soil and poor drainage.
How to fix it
Allow the soil to dry out, and if necessary, repot the plant in fresh, well-draining soil.
Pest infestations (aphids, spider mites)
Why it happens
Common in dry conditions or when plants are stressed.
How to fix it
Regularly inspect the plant, and treat infestations with insecticidal soap or neem oil.
Poor flowering
Why it happens
Can result from insufficient light or nutrient deficiency.
How to fix it
Ensure the plant receives adequate sunlight and fertilize regularly.
Care through the year
Spring
In spring, prune back any dead stems and fertilize to promote new growth. Ensure the plant has adequate sunlight as it begins to leaf out.
Summer
During summer, maintain consistent watering and deadhead spent flowers to encourage continuous blooming. Monitor for pests and diseases.
Fall
In fall, reduce watering as temperatures drop, and prepare the plant for cooler weather. If grown in pots, consider bringing it indoors before frost.
Winter
In winter, minimize watering and keep the plant in a cool, well-lit area. If indoors, maintain humidity levels to prevent stress.
Toxicity & Safety
Thunbergia alata is considered non-toxic to pets and children. However, ingestion of large quantities may cause mild gastrointestinal upset.
Good to know
Why are my Thunbergia alata leaves turning yellow?
Yellow leaves can indicate over-watering or a lack of nutrients. Check the soil moisture and adjust your watering schedule, and consider fertilizing if you suspect nutrient deficiency.
How often should I water my Blackeyed Susan Vine?
Water your Thunbergia alata every 3-5 days during the growing season, allowing the top inch of soil to dry out between waterings. In cooler months, reduce watering to every 7-10 days.
What is the best light for Thunbergia alata?
This plant thrives in full sun to partial shade, ideally receiving 6-8 hours of direct sunlight daily. Ensure it is placed in a bright area for optimal growth and flowering.
How do I propagate Thunbergia alata?
You can propagate this plant through stem cuttings or seeds. For cuttings, take healthy stems, remove lower leaves, and place them in moist potting mix. For seeds, sow them in spring after the last frost.
When should I prune my Blackeyed Susan Vine?
Prune Thunbergia alata in early spring to encourage bushier growth and remove any dead or damaged stems. Regular deadheading of spent flowers will also promote more blooms.
What should I do if my Thunbergia alata is not flowering?
Poor flowering can be due to insufficient light or nutrient deficiency. Ensure the plant receives adequate sunlight and fertilize regularly to encourage blooming.
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