Black-eyed Susan vine is a tropical plant with sunny daisy-like flowers. While it is not related to rudbeckia (aka black-eyed Susans), the flowers resemble them closely. They have five petals and a dark circular center.
This vine is only hardy in USDA zones 9-10, which makes it an annual for most American gardeners. It is great for adding color and height to our garden beds and containers. It’s vigorous and fast-growing too. Let’s dive into how to grow Black-eyed Susan vines!
Overview
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Seed Varieties
Black-Eyed Susan
Black-Eyed Susan Vine Seeds
Spanish Eyes
Spanish Eyes Black-Eyed Susan Vine Seeds
Plant History
Introduced to Europe in the 19th century, this vine is cherished for its vivid flowers.
Black-Eyed Susan vine, known by the scientific name Thunbergia alata, is native to East Africa. It was named after Swedish botanist Carl Linnaeus’s pupil, Carl Peter Thunberg.
It was introduced to Europe in the 19th century and gained popularity for its bright yellow flowers with dark centers. This pretty flowering vine is now widely cultivated as an ornamental plant in gardens and is loved for its vibrant blooms.
Please note: if you live in a tropical zone such as Hawaii or Puerto Rico, it is considered invasive and should be avoided.
Cultivation
Varieties vary in flower color, size, and growth habits.
There are several varieties and cultivars available, each with unique characteristics. Common variations include differences in flower color, size, and growth habits. I will share some of my favorite varieties in the varieties section below.
Propagation
There are many ways to propagate and grow these pretty flowering vines. Since they are annuals in most regions, it’s nice that they can be propagated in some inexpensive ways.
Purchase
This popular annual is widely available at nurseries.
When bedding annuals come out in your local garden center or nursery, you will likely find black-eyed Susan vines. Quite often, they will come already growing on trellises. Or you can find smaller ones that you can plant directly into your garden or containers.
Cuttings
Propagate via cuttings, rooting them in moist soil, and checking growth after a week.
If you bought a black-eyed Susan plant, you can always take cuttings from it to make more. You will want to choose a young, healthy part of the plant and cut it below a node (where the leaf meets the stem). Dip the cut tip into a rooting hormone powder. This is optional, but it does help your cutting develop roots faster.
Next, place the cut end into a container prepared with evenly moist seed starting mix (potting soil works in a pinch, too). Plant it deep enough to cover the node, and so the stem is firmly planted. Place a plastic cover or dome over it to keep the moisture in. Place it in bright but indirect sunlight.
After about a week or so, uncover your cutting. You should be able to tug it gently, and it will not pull out easily if the rooting is successful.
You can overwinter the plant in your house. Then, take cuttings from that mother plant to create more new plants.
Seeds
Black-eyed Susan seeds can be planted outdoors after frost or indoors 4-6 weeks before the final frost for earlier blooms.
This annual can be easily grown from seed. If you have a large area you want covered in this flowering vine, this is a very inexpensive way to do it.
Direct Sow
Plant the seeds directly into the garden. Wait until the danger of frost has passed. Soak your seeds for a few hours or overnight before planting them. Choose a sunny location with moist, well-drained soil (more about ideal growing conditions in the ‘how to grow’ section). Keep them watered as they sprout and grow.
Start Indoors
To get your vines to mature and flower faster, you can start them indoors. This is especially important if you live in a colder zone and have a shorter growing season. Start your seeds 4-6 weeks before the final frost. It may seem like an even better idea to start them earlier. But starting them earlier makes it harder for them to transition out into the garden. It is best to start them only 4-6 weeks before they will go outside.
Sow them in containers prepped with evenly moist seed starting mix or potting soil. Do not bury the seeds deep into the soil. Just brush a bit of soil over them, as they require light to germinate. Place a dome lid of some sort over them to keep the moisture in, and place them in bright indirect sun.
Check on them often. They should germinate in 12-21 days. Once they start to sprout, move them to a sunny location (or under grow lights). Harden them off, then transplant them outdoors after all danger of frost has passed.
If you live in a warmer zone (10+), you can let your plants go to seed. They will self-seed and grow new vines the following season.
Planting
Select a fitting location, plant in compost-mixed soil, and water thoroughly.
Choose a suitable location (check out the ‘how to grow’ section below to determine an ideal location). Dig a hole about two to three times larger than the plant container itself. Gently remove the vine from its pot and place it into the hole.
I use a mixture of about one-third compost with two-thirds of the existing garden soil. Make sure the soil line is level with the crown of the plant (where the stem meets the roots). Fill the soil around it and firmly press your plant down into place.
Give it a good deep soak to help the plant establish. This is best done on a cloudy or rainy day. If that is not possible, try planting in the early morning or the evening as opposed to the heat of the day.
How to Grow
If grown in their ideal conditions, these vines grow vigorously and flower continuously through the summer months. Let’s examine what the ideal conditions are.
Sunlight Requirements
This vine requires full sun to part shade, at least six hours daily, for optimal growth and blooming.
This flower thrives in full sun to part shade conditions. Ensure that it receives at least six hours of sunlight each day to keep it growing and blooming to its full potential.
If it looks spindly, stretches towards the light, and has few blooms on it, it needs more sun. On the flip side, if it is getting scorched leaves and is constantly drooping, that’s a sign it is in too much direct sun, especially in the heat of the day.
Soil Requirements
They prefer well-draining, loamy soil enriched with organic matter for healthy growth.
Provide rich, loamy, loose soil. If grown in a container, potting mix works best. If you are growing it directly in your garden, make sure your soil is amended with lots of organic matter, and you might even need some coconut coir or peat to lighten it up.
This plant hates being waterlogged, so having loose soil is important. I do a quick soil squeeze test to determine if the soil is too heavy. Grab a handful of soil and squeeze it in your hand. If it sticks together like a ball of putty, it has a high clay content and will not drain freely.
You need to add lots of organic matter in the form of compost, aged manure, worm castings, or sea soil. Also consider adding coconut coir or peat to the bed. This will loosen the soil and help it drain water easily.
Water Requirements
Wilted plants often recover with a deep, thorough watering.
Keep the soil evenly moist. These vines do not like to dry out. I had a client with beautiful black-eyed Susan vines I planted in two containers by their back door. Every week, when I came to maintain their garden, the vines looked dead. They were wilted to nothing. After pouring two huge jugs of water into each, they would almost magically perk back up. I don’t recommend letting them get to that point. It stressed them, and they never bloomed to their fullest. But, if you think you’ve killed your vine, there’s a good chance it just needs a good drink. Don’t let them get to the crispy point of no return.
Ideally, keep them evenly moist at all times. If they are growing in containers, that might mean daily or twice daily watering, depending on the size of the container and the amount of sunlight they receive.
If your container or hanging basket is dry, I recommend taking them and placing them in a small tub or shallow container with water and letting the plant soak up water from the bottom (if they’re easy to lift and move). I have a small tub I keep in my greenhouse specifically for this purpose. Sometimes, when plants in containers get really dry, water poured on them will pour straight out the bottom without any absorption. Bottom watering ensures they soak up the water.
Climate and Temperature Requirements
Black-eyed Susan, perennial in zones 9-10, are annuals elsewhere and potentially invasive in warm climates.
These tropical vines thrive in zones 9-10. In other areas, they are treated like an annual that gets replanted every season.
They prefer protected locations out of the wind. That’s why they are great in containers near the house or perhaps against a fence or on a trellis in a small protected garden.
In warmer zones where they do thrive, they thrive too well. They are considered invasive and should not be planted in Hawaii and Puerto Rico.
Fertilizer
For Black-eyed Susan, use high-phosphorus fertilizer every two weeks in summer after watering to avoid burning.
I fertilize black-eyed Susan with an all-purpose fertilizer or one that has an emphasis on blooms. The bloom formulas have a high middle number, phosphorus, which is what is responsible for flowers and fruit. I fertilize every two weeks in the summer.
Make sure to always water your plants before fertilizing. Fertilizing dry plants can burn them.
Maintenance
Care is easy; provide a support to climb and prune as desired.
Black-eyed Susan vines require only a bit of maintenance. If you want them to climb, you need to provide support for them to twine and climb. A trellis, obelisk, arbor, or chain link fence all work great.
You do not need to deadhead to keep it blooming. You can prune and shape the vine if you wish.
Varieties
The blooms are most commonly bright yellow with dark centers. But there are other varieties available that have some different colors that might suit your garden better than the traditional yellow one.
‘Bright Eyes’
The white petals and black center of ‘Bright Eyes’ are perfect for bridal displays or moon gardens.
‘Bright Eyes’ is a white variety. It features bright white petals and a black center. It would look great in bridal floral displays. Or it can be used in a moon garden to naturally illuminate walkways at night with its bright white flowers.
‘Tangerine Slice A-Peel’
This variety has reddish-orange petals with yellow stripes and a dark center.
‘Tangerine Slice A-Peel’ is a colorful variety. It features reddish orange petals with yellow lines dividing the five petals. Then it has a dark center. It would be a unique addition to a container. It looks very exotic.
‘Blushing Susie’
With a mix of yellow, peach, and pink, ‘Blushing Susie’ brings vibrant colors to your garden.
‘Blushing Susie’ is a soft and romantic variety. It has flowers that come in various shades of soft yellow, pale peach, and rosy pink on a single vine. They all have the classic black center. It’s multifaceted and brings a lot of color to your garden or containers with only a single plant.
‘Spanish Eyes’
Bursting with sunset-colored blooms, ‘Spanish Eyes’ complements mixed containers or trellises beautifully.
‘Spanish Eyes’ is a colorful variety that blooms five-petalled flowers in sunset shades. This dreamy variety looks great in mixed containers planted with calibrachoa with similar colors, such as ‘Eyeconic Compact Sunset’. Or plant it on its own on a trellis or fence for an explosion of fiery color.
Design
Feature the vine as a striking centerpiece in containers.
Black-eyed Susan vines add height and color to container arrangements, making them a wonderful ‘thriller’ plant to be the centerpiece. Choose a large container and place a small trellis or garden obelisk in the center.
You don’t even need to add any other plants. The vine will fill the pot, grow tall, and be full of five-petaled flowers. Or, you can place the trellis more towards the back of the pot. Then, fill the front with filler and spilled plants. Geraniums and ivy or ‘wave’ (trailing) petunias would be a good choice for an explosion of flowers.
You can also feature the plant as a ‘spiller’ in containers. These are the plants that trail downwards and pour out of the pot. Use them in hanging baskets on their own or mixed in with other flowers. They can also be planted as trailers in mixed containers. Perhaps a canna lily in the center, with petunias and the flowering vines spilling out the edges.
Pests and Diseases
Black-eyed Susan vines don’t usually struggle with pests and diseases. If you are having problems, it is most likely because they are not growing in their ideal conditions. Let’s examine some of the pests and diseases that could be affecting your plant.
Powdery Mildew
Prevent powdery mildew with a good watering routine and a sunny location.
Powdery mildew is a fungus that will coat your plants in a powdery film that dusts off. This coating stunts and can eventually kill your black-eyed Susan vine.
Powdery mildew attacks weakened plants. Make sure your black-eyed Susan is meeting all its growing requirements. That is six hours of sunlight and moist, free-draining soil. If any of these requirements are not met, the plant becomes more susceptible to fungus-like powdery mildew.
Another issue is watering. Spraying the foliage of your vine leaves your plant more susceptible to powdery mildew. When watering, only water the soil line. I use a drip hose snaked through my garden. If I’m watering containers, I aim for the soil as opposed to the foliage. Or water from the bottom of the container by placing the container in a tray of water and letting it soak it up.
Another tip to prevent powdery mildew is water timing. Watering in the morning is preferable over night watering. If you water early in the morning, the sun will dry the foliage. Whereas, watering later leaves the leaves wet during the night and vulnerable to mildew.
Of course, we can’t always control things like rainy, humid weather. Sometimes, powdery mildew happens. If you do spot it, make sure to clean up the vines. If the disease persists even after removal, dispose of them to avoid reinfection next season.
Unfortunately, normal fungicides don’t have much effect on powdery mildew. You can attempt to pre-treat if you know it’s been an issue in the planting area previously, or avoid planting there altogether.
Spider Mites and Whiteflies
Ideal growth conditions and early pest detection protect Black-eyed Susan from spider mites.
Spider mites are small, red, spider-like bugs that form networks of silky webs all over your plants as they feed on plant sap. This feeding weakens and eventually kills the plant with no intervention.
Spider mites prey on already weakened plants. Make sure your black-eyed Susan vine is growing in its ideal conditions. As mentioned above, that includes six hours of sunlight, moderate water, and light, well-drained soil.
Whiteflies feed in a similar way. If you brush your plant and see tiny white moths flittering away, you’re dealing with whitefiles. The best treatment for them is blasting them with water.
It is a good idea to inspect plants periodically for pests. Spider mites and whiteflies are much easier to deal with if you catch them early. You can purchase an insecticidal soap and spray according to the directions on the label.
If the infestation is really bad, sometimes I just cut my losses, pull the plant, and dispose of it.
FAQs
A: For an average-sized container (12”) or hanging basket, plant three small vines in a triangle a few inches apart. They will grow large and fill in.
A: No, they are considered non-toxic.
A: Yes, if you live in a warm zone (USDA 9-11), they self-seed and regrow readily. In tropical zones, such as Hawaii and Puerto Rico, they are invasive because of their self-seeding abilities.
Final Thoughts
Black-eyed Susan vines are such vibrant, sunny flowering plants to grow. They grow quickly and bloom all summer long. They look great in containers or climbing up fences and trellises. These versatile, easy-to-grow vines are a great addition to your garden.
