Black-eyed Susan Grow & Care Guide

Written by Iris

Jan 03 2023

Black-eyed Susan Grow & Care Guide
Black-eyed Susan is a tropical plant native to South Africa. It is named after its black flower center. A major feature of Black-eyed Susan is that it grows close to 3 meters in height and has very beautiful flowers. But how to grow black-eyed Susan? What should we pay attention to when caring for the flower?

How to Grow Black-eyed Susan

Black-eyed Susan Propagation with Seeds

Most gardeners propagate Black-eyed Susan Daisy-Like Flower from seed. The seed coats are very hard so you will need to soak them overnight before planting them. I use what I call the cup & saucer method. I soak my seeds in teacups which I cover with their saucers to keep my curious cats (or curious children if you have them) out. Because I am usually soaking different kinds of seeds, I place the seed packet under the teacup so I know which is which.
You can direct sow your seeds in your garden in the spring when they soil has warmed to 60⁰F. Install your support system where you intend to grow your vines. The reason you would want to direct sow the seeds in your garden is that the plants do not transplant well because they don’t like having their roots disturbed. Plant the seeds ¼ inch deep around the support. Germination should occur in 2 to 3 weeks. I always keep an eye on any vines I am growing to make sure that they are able to climb the support. Sometimes I have to give them a little help by guiding them to the support. Occasionally I even loosely tie the vines to the support using string which I remove later.
You can also start your seeds indoors. It’s best to use biodegradable containers such as peat pots because black-eyed Susan vines do not like their roots disturbed. Using a peat pot allows you to transplant your seedlings into your garden without disturbing the roots. The pot will gradually break down during the growing season and add nutrients to the soil.
After pre-soaking your seeds, fill your peat pots with soil and plant your seeds ¼ inch deep 6 to 8 weeks before your last frost. Keep the soil moist. Germination should occur in 2 to 3 weeks. You can plant your seedlings in your garden after all danger of frost has passed and night time temperatures are consistently above 50⁰F. Be sure to install your supports before you plant your seedlings. If you plant your seedlings first and then try to install your supports, you will risk damaging your plants.

Black-eyed Susan Propagation with Stem Cuttings

Propagating this vine from stem cuttings is easy and it's usually best done over the winter.
  • Take a cutting several inches from a terminal end of a healthy plant.
  • Remove the bottom leaves of the cutting.
  • Place the cutting in a glass of water to root.
  • Change the water in the glass every two or so days.
  • When the roots thicken, plant it in a well-draining pot in potting soil.
  • Grow the plant until spring and then transplant outdoors after the threat of frost has passed.

Black-eyed Susan Propagation by Layering

Thunbergia alata can also be propagated by “layering.” To do this:
  • Look for a vine growing close to the ground and bend it downwards.
  • Measure 8″ inches from where the vine ends and cover it with soil
  • Tie up the vine to prevent it from being destroyed by the wind
  • Ensure the area in contact with the soil remains moist by watering
  • After the roots develop, use the vine just before them for replanting.

How to Care for Black-eyed Susan

Lighting Requirements

Black-Eyed Susan vines grow best with a combination of sun and light shade, and in the hotter regions, they require shade during the afternoon. They will continue to bloom as long as they get several hours of sun daily and the temperature remains above 60 degrees.

Soil Care

Plant a black-eyed Susan vine in soil that is rich, fertile, and well-drained with medium moisture-retention properties. It prefers a soil pH that is close to neutral.


Black-Eyed Susans are tropical plants and are not drought-tolerant. A layer of mulch will greatly help the soil retain its moisture. The soil in baskets or containers must not be allowed to dry out completely. Water regularly and thoroughly.

Temperature & Humidity Care

The black-eyed Susan vine thrives in warm, humid climates, which explains why it is invasive in tropical areas. However, it will grow anywhere in its zone range, provided it gets enough water. It tends to flower best after the hottest days of the summer are over.


These robust growers are using up a lot of energy in flower production and, like all potted plants, appreciate being replenished. Use a well-rounded, organic fertilizer throughout the growing season, approximately every 4-6 weeks as new growth and blooms develop. Treat Black-eyed Susan well and it'll reach a height of around 10ft. (Find more fall flowers here.)


Once established, this vine can be trimmed and shaped (lightly) during the growing season, but any heavier pruning should be done in the early spring before the new growth starts.

Pests & Diseases Care

These plants, especially those grown outside, are not prone to many pests and diseases. As long as the plants receive enough water, sun, and air circulation, they should perform well.
When grown as an indoor plant, the black-eyed Susan vine is prone to plant scale, whiteflies, and spider mites. This is a significant problem in areas with hot weather. Insecticidal soap can quickly fix the issues. Keep on the look out for stem and leaf damage a sign of pests and diseases.

Black-eyed Susan Varieties

  • ‘Becky Mixed’offers a variety of colors for your garden, such as lemon-yellow, golden-yellow, dark red, and reddish-brown.
  • ‘Sonora’which has bright yellow flowers.
  • ‘Toto’which is a dwarf type and ideal for containers.

Black-eyed Susan Care FAQ

Will Black-eyed Susan spread?

These colorful plants are true vining plants and will definitely create a carpet or column of colour if left to their own devices. They make beautiful hanging baskets, will climb up a trellis, cover a wall or mailbox with ease, and will continue to bloom from spring to fall. In warm climates, they easily root into the soil and produce new plants via self-seeding. If you need to keep them contained, consider potting them and allowing them to grow upward. (Read More: Are Black Eyed Susans Deer Resistant)

Why Is Your Black-Eyed Susan Vine Not Blooming?

Black Eyed Susan vine (Thunbergia alata) is very picky when it comes to when and where it blooms. If you don't provide it with the perfect conditions, it won't bloom.
 If your Black Eyed Susan vine stopped flowering, the most common cause is that the environment is too hot. Give the plant a cool, sunny environment and protect it from scorching heat.
There are other causes too, such as: poor soil, no pruning or too much fertilizer
Diseases and pests most often won't affect a Black Eyed Susan vine’s blooming schedule. Don't feel bad if your Black Eyed Susan vine doesn't bloom. In most cases, it's due to factors outside of your control.