Once you’ve added stevia to your garden, it’s important to consider how it will fare through the colder months. Though stevia can live for several years, its survival depends on how well it can handle your region’s winter conditions.
Stevia is not frost-tolerant. It is a tender perennial that cannot survive freezing temperatures. However, it thrives in zones 9 to 11. In zones 8 and lower, bring it indoors or treat it as an annual.
Learn how to provide the right conditions and care to support stevia’s growth. This article will guide you through those essentials.
IDEAL CONDITIONS FOR STEVIA
SUNLIGHT AND TEMPERATURE: Stevia is a sun-loving plant that requires full sunlight for at least 6 to 8 hours each day to grow strong and produce its sweet leaves. Monitor and prune neighboring plants and trees so they do not cast too much shade on your stevia.
Stevia thrives in temperatures above 70°F (21°C) and does not tolerate frost well. If frost is common in your area, consider container planting stevia so you can bring it indoors during cold snaps.
SOIL: Stevia needs well-draining soil. Soil that holds too much water can cause root rot, which may harm or kill the plant. This plant prefers soil with a pH of 6.7 to 7.2. You can test your soil pH at home with a commonly available test kit.
WATERING STEVIA
To keep stevia healthy, water it regularly to maintain consistently moist soil, but avoid overwatering. Check the top inch of soil—if it feels dry, it’s time to water deeply until water starts to drain from the bottom of the pot. Avoid allowing the plant to sit in excess water.
EFFECTS OF DROUGHT STRESS
When stevia plants don’t get enough water, they can experience drought stress. Here’s what happens:
- Leaf Wilting: The leaves may start to wilt or curl. This happens because the plant is losing more water than it can take in.
- Stunted Growth: Without enough water, the plant’s growth can slow down. You might notice fewer new leaves and smaller plants.
- Reduced Yield: If you’re growing stevia for its leaves, a lack of water can lead to lower leaf production and less sweet flavor.
EFFECTS OF OVERWATERING
Overwatering is just as harmful as not watering enough. Here’s what can go wrong:
- Root Rot: When the soil is too wet, the roots don’t get enough air. This can lead to root rot, where the roots start to decay and the plant can’t take up nutrients properly.
- Leaf Yellowing: Overwatered stevia plants might show yellowing leaves. This happens because the roots are damaged and can’t support the plant.
- Poor Growth: Too much water can stunt growth. The plant may not grow as well or may even start to die if the roots are severely affected.
WATERING METHODS
When it comes to watering your stevia, you have a few choices: watering by hand, using a drip irrigation system, or relying on rain. Each method has its pros and cons, but the best choice depends on your garden’s needs.
- Watering by hand: This is when you use a watering can or hose to give your stevia plants a drink. It’s good because you can control how much water each plant gets. However, it can be time-consuming, especially if you have a lot of plants.
- Drip irrigation system: This method uses tubes that slowly drip water directly to the roots of your plants. It’s the best choice for stevia because it provides consistent moisture without getting the leaves wet. Wet leaves can sometimes lead to disease. Drip irrigation also saves water because it targets the roots instead of soaking the entire area.
- Relying on rain: While rain is natural and free, it’s not always reliable. Too much or too little rain can cause problems for your stevia plants. If you only rely on rain, your plants might not get the consistent water they need.
PRUNING STEVIA FOR OPTIMAL GROWTH
Without pruning, stevia tends to grow on a singular, tall stem. Regular pruning helps stevia grow more branches and leaves, making it bushier and more productive. You can see here how the pruning cut has forced my plant to form two new branches. Pruning is a great time to gather the sweet stevia leaves for your harvest. I usually wait until my stevia has branches that are perfect for propagation cuttings. I look for stems that are 2 to 3 inches long and have a leaf node on the bottom half that I can trim the leaves off of. That leaf node will be where the plant creates new roots. We will have an article on propagating stevia soon. I have a great collection of photos and failures to share with you.
Prune your stevia in the morning, when the plant is fully hydrated and before it flowers. Start pruning when the plant is about 8 inches tall and continue every few weeks to encourage new growth. Use clean, sharp scissors or pruning shears and cut above a pair of leaves, about 3 to 4 inches from the top. Remove any flowers or buds to help the plant focus on leaf production.
PINCHING FLOWERS: Once your stevia flowers the leaf production will slow down. To keep leaf production robust, many gardeners will pinch off any flower starts. I’m not the most attentive gardener so I can attest to the fact that once my stevia flowers it becomes straggly.
If your stevia plant has grown tall and leggy, you can cut back up to one-third of the plant’s height. This will make the plant bushier and produce more leaves.
However, I was surprised to find an abundance of differing opinions online about the relationship between flower pinching and stevia’s leaf sweetness. Some say that pinching off flowers helps the plant stay sweet and not become bitter. Others say that pinching off the flowers will make the leaves lose their sweetness. This is definitely an experiment we will have to run at HerbDiggers.Com to see what the truth is.
For now, I can confidently tell you that pinching flowers is a type of pruning and it will make your stevia plant more productive. My perfectly uneducated guess as a run-of-the-mill gardener is that the leaves harvested before stevia flowers will be sweeter because the plant can focus energy on leaf development instead of growing flowers.
MANAGING PESTS AND DISEASES
PESTS: Keep an eye out for pests such as aphids, spider mites, and whiteflies.
Aphids can be removed by washing them off with water. I use dish soap. When you spray a mixture of dish soap diluted with water on aphids, it works by suffocating them. The soap breaks down the protective outer layer of the aphids, causing them to dehydrate and die. Additionally, it can disrupt the aphid life cycle by coating and potentially suffocating eggs as well.
Spider mites can be controlled by spraying the plant with water, using insecticidal soap, or by using the dish soap method mentioned above.
Whiteflies can be managed with a handheld vacuum or natural insecticides like neem oil. Regular inspections will help you catch and address these issues early.
DISEASES: Prevent root rot by using well-draining soil and avoiding overwatering. Leaf spots, caused by fungal infections, can be managed by watering at the base of the plant and removing affected leaves.
WINTER CARE FOR STEVIA
OVERWINTERING INDOORS: If you live in a region with frost, bring your stevia indoors before the first frost. Inspect the plant for pests and diseases before bringing it inside. Place it near a sunny window or use a grow light if natural light is insufficient. Water only when the top inch of soil is dry and keep the room temperature between 60°F and 75°F. Regularly pinch back leaves to promote bushiness.
STEVIA IN MILD WINTER CLIMATES: For mild winter climates, protect stevia outdoors with mulch, covers, or cold frames. Apply a thick layer of mulch around the base to insulate the roots. Use frost cloths or blankets on cold nights and remove them during the day. Cold frames can also help by providing a mini-greenhouse effect.
FERTILIZING STEVIA
NUTRITIONAL REQUIREMENTS: Stevia needs a balanced diet of nitrogen (N), phosphorus (P), and potassium (K). Nitrogen promotes growth, phosphorus supports root development, and potassium enhances disease resistance. Magnesium, calcium, iron, and zinc are also essential.
FERTILIZING ROUTINE FOR STEVIA: Start fertilizing in early spring with a balanced organic fertilizer (NPK ratio of 10-10-10 or 14-14-14). Apply around the base of the plant, avoiding direct contact with leaves. Fertilize again in mid-summer to support continued growth, and reduce application in late summer/fall to prepare the plant for winter dormancy. Too much fertilizer during this period can lead to weak growth and susceptibility to disease. It is best to familiarize yourself with the directions on your fertilizer packaging.
FERTILIZING POTTED STEVIA: Fertilize stevia in pots more frequently because they have limited access to nutrients. Use a balanced organic liquid fertilizer every two weeks. When using store bought liquid fertilizer, be sure to dilute it according to the package instructions. You can also use plant food spikes, which can last up to eight weeks.
SIGNS OF STEVIA’S NUTRITIONAL NEEDS
| NUTRIENT | DEFICIENCY SYMPTOMS |
| Nitrogen | Pale yellow leaves, stunted growth |
| Phosphorus | Dark green leaves with reddish-purple veins, poor growth |
| Potassium | Yellowing or browning leaf margins, weak stems |
SIGNS OF TOO MUCH FERTILIZING: A nutrient surplus may lead to burnt leaves and poor root development.
IN CONCLUSION
To have a successful stevia harvest, make sure the plant gets plenty of sunlight. Use soil that drains well so the roots stay healthy. Water the plant regularly, but don’t overdo it.
It’s also important to prune the plant often and keep an eye out for pests. This will help keep your stevia strong. If you live in a place with cold winters, protect the plant during those months so it can survive.
By taking these steps, your stevia plant will stay healthy and produce lots of sweet leaves.
Article 037, Contributor/s: Sheryl CS Johnson and Carol Schwinn