Gelsemium

( jel - SEEM - ee - um )

At-A-Glance Information

This genus of flowering evergreen vines includes species which need full sun to partial shade and regular waterings for best flowering and foliage growth. They are native to the North America, China, and Southeast Asia and produce shrubby, twisting vines that reach up to 20 feet in length. Flowers are bright golden-yellow. These plants can be used as climbers or groundcover, or as specimen vines in containers. Take care when planting these vine in the garden, as all parts are highly toxic to humans and pets if ingested.

Gelsemium Species and Varietals

The genus Gelsimium is the type genus member of the plant family Gelsemiaceae, and includes just three species. These vines grow best in USDA hardiness zones 7-10 or Sunset growing zones 4-24. To find your zone, click here: Zone Map.

Gelsemium elegans (Heartbreak Grass, Graceful Jessamine, Ngouane dok Leuang)
These plants, although beautiful, are more famous for their use by humans than their foliage or flowers; crumbled leaves of this plant were used in high-profile poisonings in 2011 and 2012. Individual vining stems can reach up to 40 feet or more in length. Foliage is green and glossy and flowers are orange to yellow, small, and funnel-shaped.

Gelsemium rankinii (Swamp Jessamine, Rankin's Trumpetflower, Swamp Yellow Jessamine)
This vine produces flowers with no fragrance, and blooms in spring and fall. This species needs ample water, and does well in boggy conditions. It is native to the southeastern United States, and produces green foliage and golden yellow flowers. They can reach over 20 feet tall or long, climbing over other vegetation for support.

Gelsemium sempervirens (Carolina Jessamine, Yellow Jessamine, Confederate Jessamine, Confederate Jasmine, Evening Trumpetflower, Woodbine, Poor Man's Rope)
This species produces fragrant flowers in late winter and early springtime, and needs regular water in its early years, becoming more tolerant of less water as it matures. Variety 'Pride of Augusta' ('Plena') is a double-flowering form. Vining stems can reach up to 10-30 feet long.

Caring for Gelsemium

Take care when planting this vine in your garden, as all parts are highly toxic if ingested. These vines do best when planted in full sun; ideally, they should be receiving between 6 and 8 hours of direct sun each day. Soil should be well-draining and relatively fertile. If local soils are compacted, do not drain well, or are particularly poor in nutrients, make sure to amend the planting area with plenty of organic matter or compost before installing. Apply a thick layer of mulch around the base of the plant after installation, ensuring that mulch stays at least a few inches away from the stems. This will increase soil moisture retention, suppress weed growth, and maintain a constant soil temperature. Water newly planted Carolina Jasmine vines regularly until they establish a strong root system. When mature, these plants appreciate regular waterings to maintain even soil moisture around their roots.

No pruning is necessary for these plants, unless their size or shape needs to be controlled. Each spring, remove any dead, damaged, diseased, or crossing branches to improve the health of the vine and airflow through the foliage. Each year in springtime, pull back mulch, apply a thick layer of compost around the base of the plant, and work it into the soil. Replace mulch after fertilizing. These vining plants can survive for many years in the garden, and spreads via a network of suckers, possibly persisting indefinitely in the landscape.

Propagation

When working with Gelsemium, take great care in ensuring that plant parts do not get left in areas with children or pets, as they are very toxic. Gelsemium vines can be propagated either by using cuttings or from seed. To ensure that your propagated plant will have the exact same qualities and characteristics as the parent plant, use the cutting method. If you would like to experiment and see what plant you can grow from seed, just keep in mind that it will not necessarily be the same as the parent plant. To propagate your Jessamine, follow the instructions below:

Propagating Gelsemium by Cutting

Gather your materials. You'll need a clean, sanitized, sharp pair of garden shears, rooting hormone, a pencil, and a 3-inch pot filled with well-draining compost or other organic material. A good substrate for propagation of cuttings is a light blend of 1/3 pasteurized soil or compost, 1/3 sand, vermiculite or perlite, and 1/3 coconut coir or peat moss.
In spring or early summertime, choose the plant that you'd like to propagate. Ensure that this plant has had a good watering the night before, as this will improve the chances your cutting will take root. Cut one or more 6 inch portion(s) of the end of a non-blooming branch and strip the leaves off of the lower half. Make a hole in your planting medium by pushing your pencil into the soil. Dip the end of the stem in rooting hormone, and plant it in your pot. Fill in soil around the cutting to support it, but do not pack it down too much.
Moisten with water, and ensure that the pot has good drainage. Your pot should be kept in warm, sunny conditions indoors (and not in direct sunlight). Water whenever your soil is dry under the top layer. After about four to six weeks have passed, your cutting should be rooted. When you notice new growth, you'll know you have roots.
Keep your new plant in an area with bright light (though not direct sunlight) and temperatures between 55 and 70 degrees Fahrenheit. Ensure that the soil stays moist, but not wet, until the next spring, when you can transplant it to its new home. Ensure that the last frost of the year has occurred before doing this, as it can seriously damage your new shrub.

Propagating Gelsemium by Seed

Keep in mind that the plant you get from seed will not necessarily mimic all of the characteristics of the parent plant. To propagate by seed, you will need a paper bag, a pot or tray filled with well-draining compost or other organic material, a spray bottle and a fork. The best potting medium for seed germination is a light blend of 1/3 pasteurized soil or compost, 1/3 sand, vermiculite or perlite, and 1/3 coconut coir or peat moss.
Harvest your seeds. The seed pods on Caesalpinia plants are pretty easy to spot, they're large and dangle from the branches, left behind after flowers have faded. Once they have dried out and begun to split open, you can harvest the seeds inside. Cut them off of the plant, placing them in a paper bag. Harvest as many as you can, and place the paper bag in a dry, cool, dark area. They will begin to split open and release the seeds contained inside. Once they have been released, take them out of the bag and put them in a container so you can work with them.
Caesalpinia seeds have a hard coating that protects them, but this coating also makes it a little difficult to get them to germinate. We can help the process along by scarifying them with sandpaper (or simply rubbing them against an abrasive surface). Do this with as many seeds as you can; they will probably not all sow, and the ones that do will be of varying characteristics. The more seeds you plant, the more chances you will have to get the resulting shrub you want. Place your seeds in lukewarm water for six hours. Viable seeds will sink to the bottom, and non-viable seeds will float to the top. You can discard any seeds that float.
Water your prepared seed tray or pot filled with soil, and ensure that good drainage is occurring. Place your seeds in your prepared pot or seed tray about a quarter inch to a half-inch under the soil surface. Cover them with soil and water with your spray bottle. Place your tray of seeds in a warm area that receives bright, indirect light. A greenhouse is the most ideal climate, but a planting tray inside a window will do as well. Germination usually takes 7-14 days from sowing. Once you begin to see seedlings sprout and they are able to be handled, transplant them to their own individual 3-inch pots, filled with the same potting medium as described in Step 1. Loosen the seedlings from the potting medium by digging down with the tines of your fork about an inch and a half, gently working the seedling up until it is out. Then, replant the seedling in its individual pot.
Keep the seedling's potting medium moist, but not wet, by spraying the soil with your spray bottle. Keep your new plant in an area with bright light (though not direct sunlight) and temperatures between 55 and 70 degrees Fahrenheit. Ensure that the soil stays moist, but not wet, until the next spring (after the danger of frost has passed), when you can transplant it to its new home.