Thunbergia alata
Black-eyed Susan vine
Common names: Black-eyed Susan, Bush clock vine
At a glance
- Light
- Full sun
- Hardiness
- Cold damage below 5 °C
- Flowering
- Jun–Oct
- Spacing
- 30 cm, rows 40 cm
- Water need
- Medium
Photo: Forest & Kim Starr · CC BY 3.0 · Source
This description was machine-translated.
Description
Black-eyed Susan vine, botanically Thunbergia alata, originates from tropical East Africa and grows in temperate regions as an annual climbing plant. Over one summer its shoots twine 1.5 to 2.5 m up canes, strings, or trellises, and it also appears trailing when grown in hanging baskets and large containers. The leaves are heart-shaped to triangular and slightly toothed. From June until the first frost, flowers appear in yellow, orange, or white, with a dark brown to black throat at the center that gave the plant its name. It blooms quickly, with the first flowers opening three to four months after sowing. It is used on trellises, obelisks, fences, and balcony railings, where it quickly provides color and privacy screening.
Care instructions
Plant the black-eyed Susan vine in a sunny, warm, and wind-sheltered spot after the Ice Saints, in mid-May. Provide a climbing aid right away: fine tensioned wires, a trellis, strings, or a bamboo cane obelisk. It twines on its own, but young shoots need to be guided onto supports during the first weeks. Pinch young plants once when they are about 20 cm tall, which encourages better branching. Water evenly, daily in containers on hot days, and never let the soil dry out completely. Regular fertilizing from June onward keeps it flowering until frost. Common mistakes include planting out young plants too early, where cold nights stunt them, a shady site, and too much nitrogen, which produces leaves instead of flowers.
The care notes were machine-translated from German.
Garden year
SowingFeb–May
FloweringJun–Oct
Germination
- Soil temperature
- from 18 °C, ideally 24 °C
- Days to sprout
- 10 to 21 days
- Light
- Sprouts in light or dark
- Sowing depth
- 1 cm
- How to start
- Start indoors, then plant out
Soil & site
Soil pH
Soil type
humus-rich, well-drained, nutrient-rich
The black-eyed Susan vine likes loose, humus-rich, nutrient-rich soil that drains water well and still stays evenly moist. A slightly acidic to neutral soil suits it. In the bed, work in mature compost before planting; in a container, use good-quality potting compost and pots with drainage holes. It does not tolerate waterlogging, which makes the roots rot, and complete drying out sets back its growth.
Feeding
Medium feeder
Months
Jun–Sep
From June, once the plant is well established, give it a liquid fertiliser for flowering plants in the water every two weeks, in a container until September. In the bed, mature compost at planting is enough, plus diluted nettle feed once in high summer. Too much nitrogen makes it produce mainly leaves and slows flowering.
Overwintering
The black-eyed Susan vine is not hardy and dies with the first frosts, so in Central Europe you grow it as an annual. In autumn, clear away the dried shoots together with the support and compost them. If you want to collect seed, leave a few capsules on the plant until they turn brown and dry, and keep them cool and dry until spring. You should not rely on self-sowing. Overwintering is possible: cut the plant back hard before the first frost and place it somewhere bright at 10 to 15 °C, with little water. Usually a fresh sowing in February is easier.
Propagation
Methods
- From seed
- Cuttings
The best way to raise the black-eyed Susan vine is from seed. From February, sow it in pots, cover the seeds with about 1 cm of compost and place them somewhere bright and warm at about 20 °C. After about two weeks the seeds come up; in cooler compost it takes longer. Prick out the seedlings once they have two pairs of leaves, and give them a thin cane to twine around early on. Sow directly in the bed only after the Ice Saints in mid-May, though it then flowers only from August. If you want to save the plant over winter, take shoot tips as cuttings in late summer, insert them in seed compost and keep them bright and frost-free.
For your garden
Grow Black-eyed Susan vine yourself
Gartenkern tells you when frost is coming, when to sow and when to harvest, for your location.
Free, no time limit
Notes from real gardens
What other gardeners have written down about this variety, anonymous and voluntary.
No notes shared yet. Will you be the first to write one down?