Gynostemma pentaphyllum, also known as the sweet tea vine, thrives in full sun as a short-lived perennial in U.S. Department of Agriculture plant hardiness zone 8 through 12, but can be grown as an annual during frost-free months in zones 1 through 7. This vining plant is native to China and Japan and is cultivated for its leaves, which are brewed for tea. It tolerates a wide range of soils from clay to sand and is not fussy about soil pH. It does require fertile, well-drained soil that is evenly moist. Starting it from seeds inside in late winter or early spring and transplanting it to the garden after the danger of frost has passed gives the sweet tea plant a head start on summer growth.
1. Preparing the Seeds
The sweet tea vine seeds can be slow to germinate, but soaking them in water before planting softens the seed coat and speeds germination. Place the seeds in a bowl of warm water and set them in an area where they will not be disturbed. Allow the seeds to soak for 24 hours. Drain the seeds and plant them immediately in prepared seed starting trays or peat pots.
2. Get the Soil Right
Seed-starting trays or peat pots filled with moist seed starter will provide your sweet tea vine seeds with the conditions they need to germinate. You can make your own seed starter by mixing equal parts peat moss and perlite or vermiculite, or purchase commercial seed starter at your local gardening or hardware store. Many gardeners prefer to start seeds in peat pots because they can be transplanted into the garden "pot and all" without the risk of damaging tender roots, but you can use trays or recycled containers if you prefer.
3. Planting the Seeds
Plant two to three seeds per pot and cover them with 1/4 inch of soil. Firm it down lightly with your hands. Keeping the soil moist, but not soggy, until the seedlings emerge is important to germination. Covering the pots or trays with clear plastic wrap with a few holes or ventilation works well for keeping soil moist, but must be checked daily to monitor the moisture level. Opening the plastic to allow air circulation may be necessary if the soil remains too wet. Some prefer to enclose the tray or pots in a food storage bag and prop the top open with a dowel or pencil. The bag can be opened or closed as needed. You can also use mini-greenhouses with a plastic cover for seed starting.
4. Light for Germination
Place the seeds in a warm area that receives bright indirect light keeps the soil warm. You may wish to place them on top of an appliance that provides gentle bottom heat, such as the water heater, to keep the soil warm. The seeds do not need direct sunlight at this point. Germination typically occurs between three and six weeks.
5. Caring for Seedlings
Once the sweet tea seedlings emerge, it is time to place them in brighter light. Begin by placing them in bright, indirect sunlight and gradually expose them to more light until they can withstand direct sunlight without showing signs of wilting. Thin the seedlings to one per pot when they are approximately 1 inch tall and have their first set of true leaves. Clip the weaker seedlings near the soil level to allow the selected seedling to grow. Pulling the seedlings from the soil may disrupt the roots of other seedlings. Plant them after the last frost.