Carolina jessamine

Gelsemium sempervirens

 The yellow buds of Gelsemium sempervirens just beginning to open in February 2026, with near peak bloom occurring in March 2026.

Summary

Originating in the Americas, Gelsemium sempervirens grows in woodland habitats from Virginia to Florida, though eastern Texas and as far south as Guatemala. (Wildflower). This evergreen twining vine can grow in Sunset Zones 4 to 24 and USDA Zones 7 to 10. (Sunset, Missouri BG). Both Sunset Western Garden Book and the Missouri Botanical Garden notes this vine can spread to 20’. The lanceolate leaves have a glossy appearance. This plant flowers in late winter and early spring, producing cymes of fragra-trumpet shaped flowers. If the flowers are pollenated, small oblong fruits will form, initially green and fading to brown over time. Several sources report that the pollen from Carolina jessamine is toxic to honeybees.

South Coast REC Results & Discussion

        The Carolina jessamine performed acceptably throughout the trial with minimal outliers. It had characteristically short, narrow leaves that grew close together along the branches, typically forming a bush around the base of the vine. Many individuals of this taxon covered nearly all of the trellis by the end of the trial with various degrees of leaf tip burn.

Throughout the first year of the trial, most individuals had some chewing insect damage, but it was not significant. They did not bloom, but they did rapidly push growth and sprawl across the trellis. Light maintenance was needed to keep some of the branches from hanging off the trellis. Going into 2025, their foliage significantly improved, with much less damage from pests and diseases. They continued to push their growth and had a bright but short-lived blooming season. Small, yellow flowers covered the entirety of these vines, practically creating a wall of bright,  delicate yellow. However, by the time the 2025 Summer Open House came around, most of the flowers had fallen away. Participants in this Open House still rated these vines as aesthetically pleasing and impressive. Throughout the rest of the year, foliage and overall appearance steadily declined as the leaves slowly yellowed. Most individuals maintained their coverage of the trellis, but a few did defoliate. This decline was reflected in lower ratings in the 2025 Fall Open House, but overall, the vines remained acceptable.

University of Arizona Results & Discussion

In 2025, Carolina jessamine performed below the acceptable minimum overall appearance rating of 3.0 at the UA for most months and for the average annual overall appearance. Foliage color changed from light green to light yellow, appearing chlorotic and developing marginal leaf burn symptoms as the season progressed. With few exceptions, no flowers were observed. The size of individual plants varied and the highest average trellis cover was 42% under medium irrigation and lowest cover at 18% under the low irrigation. Although some plants covered the trellis partially, Carolina jessamine is not recommended for the lower altitudes in Arizona in full sun due to the persistent low quality foliage and leaf burn.

University of California Davis Results & Discussion

​​In 2025 Carolina jessamine flowered from February to March at UC Davis, though data was not collected as it was outside of the flowering period. During the establishment period trials staff did some initial weaving to ensure shoots were evenly distributed across the base of the trellis. Subsequently, little maintenance was needed other than occasional weaving to minimize lopsided coverage or fill in any holes. During the winter the foliage took on a lighter, chartreuse coloration, with deeper green coloration appearing with the onset of spring. Participants at the June Open House noted that the plants looked healthy with several people noting that they enjoyed the red coloration on the new stems.

As the season progressed, some of the foliage appeared to yellow or bleach out during August and September. We think this was in response to the temperature. At our September Open House, participants’ ratings were mixed with the mean overall appearance ratings for the 50% and 20% individuals scoring 4 or above, while the 80% had a mean rating of 2.9. The individual plant on the 80% treatment was noticeably more yellow, with participants writing that the plant looked chlorotic. This does not seem to be a treatment effect as yellowing was observed on all three treatments, rather the plants including the Open House were initially selected in the spring and were re-used for continuity. The plant participants rated, 11-15, moved down in quality as the season progressed and ended up as one of the two lowest scoring individuals for the 80% treatment. To sum up the performance, Carolina jessamine is not the showiest plant, however it does perform reliably on lower irrigation maintaining acceptable to above average aesthetic appeal and serves as a harbinger of spring with its early bloom.

University of Washington Results & Discussion

        Carolina jessamine displayed consistently acceptable performance across the deficit irrigation season at UW. This taxon was consistently putting out new growth, however, due to growing habit and slow rate of overall growth, most individuals remained fairly sparse in terms of trellis coverage, however, some individuals did reach the top of the trellis by the end of the summer. Some individuals exhibited deadwood and dieback of branches after the winter, which was pruned out to increase appearance. Due to the twining growing habit, researchers spent some time weaving branches into the trellis to “train” plants to climb, however, due to the low rate of growth, no maintenance pruning was required. No flowering occurred at the UW site. Due to the slower rate of growth at our site, this taxon will likely increase coverage and flower in the early spring with longer establishment time. The small, delicate, lancelot medium-green foliage gives this species a pleasing texture. Foliage quality remained high throughout the deficit. No pest or disease damage was observed on any individuals. Open house participants noted that the lower vigor of this taxon is a plus in terms of maintenance needs, especially when compared to other tested taxa. No significant differences in aesthetic performance across the irrigation deficit treatments were observed, and this taxon can be recommended on the low irrigation, having a mean overall appearance of 3.3 across the growing season.