Gadenin日本語Get the appPinch hard and pinch often
Left alone, stevia grows as a lanky single stem, two feet (60 cm) tall, with widely spaced leaves and a flower head on top. Pinched regularly, the same plant becomes a dense bush with four or five times the leaf. Since the leaf is the entire crop, pinching is not tidying up, it is the main cultivation operation of the season.
Pinch the first time when a young plant reaches six inches (15 cm), taking out the tip above the second or third pair of leaves. After that, pinch every shoot that reaches about eight inches (20 cm), removing the top two inches (5 cm). Keep doing it through the growing season. Every pinch delays flowering, because you are removing the shoot tip where flower buds would have formed, and every pinch buys you more sweet leaf.
- First pinch at six inches (15 cm) Take the growing tip out above the second or third leaf pair. Two side shoots break from the axils below within a week or two, and the plant's shape for the whole season is set by this one cut.
- Pinch each shoot at eight inches (20 cm) Repeat on every side shoot as it reaches length, taking the top two inches. Do not wait until the plant looks untidy; by then the shoots have already started building flower buds.
- Use what you pinch Pinched tips are perfectly good leaf. Dry them, or root the best ones as cuttings. Nothing from a stevia pinch needs to go on the compost pile.
- Stop pinching in late season Once the days shorten and you can see buds forming across the plant, stop pinching and prepare to cut the whole thing for harvest instead.
Water steadily, and never let it dry out
Stevia is shallow-rooted and comes from damp subtropical grassland. It wilts fast and does not forgive: a plant that flags badly once loses its lower leaves within days, and those leaves do not come back. At the same time it hates standing wet, and roots sitting in saturated compost rot quickly. The target is soil that is damp to a finger's depth at all times but drains freely after watering.
In a container this means checking daily in warm weather and often twice a day in a heatwave, because a twelve inch (30 cm) pot of a well-grown stevia plant in full sun can empty in a single hot afternoon. In the ground, a two inch (5 cm) mulch of compost or bark is worth more than extra watering: it keeps the shallow root zone evenly damp and stops the surface baking hard.
| Condition | How often to water | Note |
|---|---|---|
| Container, hot and sunny | Daily, sometimes twice | Water until it runs from the base, then empty any saucer |
| Container, mild or overcast | Every two or three days | Judge by weight and by pushing a finger an inch (2.5 cm) in |
| Open ground, mulched | Deep soak once or twice a week | A long soak beats a daily sprinkle; shallow watering keeps the roots at the surface |
| Indoors over winter | Only when the top inch is dry | Growth slows, water use drops sharply, overwatering now is the usual killer |
Go easy on the nitrogen
This is where most growers go wrong. Stevia is a leaf crop, so the instinct is to feed it like spinach, but heavy nitrogen produces large, soft, pale leaves that are noticeably less sweet than smaller leaves grown lean. Sweetness accumulates in leaves that grow steadily, not in leaves that are forced.
A balanced liquid feed at half strength every three or four weeks through the growing season is enough for a container plant. In decent garden soil with compost worked in before planting, a plant may need nothing at all. If the lower leaves yellow and growth has genuinely stalled, feed. If the plant is green and growing, leave it alone.
Watch for the plant flopping outwards from the center in midsummer. That is usually too much nitrogen and too little light rather than a need for staking. A short cane and a loose tie will hold a heavy plant, but the real fix next season is leaner feeding and a sunnier position.
Sun, warmth and where to stand it
Give stevia the sunniest spot you have, with at least six hours of direct sun. It grows best between 68 and 86F (20 and 30C) and simply stops in cold weather; below about 50F (10C) nothing much happens at all. In a cool summer, a container against a south-facing wall or in a greenhouse will outgrow the same plant in an open bed by a wide margin.
One thing worth knowing is that stevia flowers in response to shortening days rather than to age or heat. This is why it runs to bud in late summer even on a young plant, and why a plant grown under a streetlight or in a bright indoor room may stay vegetative far longer. You cannot easily control day length outdoors, but you can slow the process down with pinching, and you can plan the main harvest around it.
Note what you did and when
Keep a running note through the season of the dates you pinched, the date you first saw flower buds, and roughly how much dried leaf the plant gave you. Flower bud date is the important one, because it is the deadline for the main harvest and it lands at close to the same point every year in a given garden.
Also note the plant's position and how much sun it actually got, and whether you fed it. When one plant in a row gives twice the leaf of the others, the reason is usually in those notes: more sun, less nitrogen, or two more pinches than its neighbors got.