Stevia is the sweet leaf: a tender perennial whose leaves are intensely sweet and can sweeten tea, baking and homemade drinks without sugar. A single plant gives you a season's worth of sweetener from a pot on a sunny step.
Use the fresh leaves in hot drinks, or dry and crumble them for a homemade sweetener. A little goes a long way — the leaves are far sweeter than sugar by weight, so start with one leaf in a cup of tea and adjust. This crop is in the Asteraceae family, needs full sun, and takes 90–120 days to reach maturity, so it pays to know what it wants before you sow. This guide covers it all: starting seeds, transplanting, soil and feeding, watering, sunlight, pests, companion plants, harvesting and the problems most likely to catch you out. Pinch out the growing tips every few weeks through summer. It doubles the leafy growth and delays flowering, which keeps the leaves sweet for longer.
Stevia at a glance
| Growing factor | What stevia need |
|---|---|
| Sun | full sun |
| Soil pH | 6.0–7.0 |
| Days to germination | 7–14 |
| Days to maturity | 90–120 |
| Spacing | 18–24 inches |
| Water needs | moderate |
| Cold tolerance | tender |
| Family | Asteraceae |
Starting seeds
Stevia are started indoors and moved outside as seedlings. Sow in trays or cells, keep the mix moist but not wet, and expect germination in 7–14 days. Give seedlings strong light from the moment they emerge — a grow light a few inches above the leaves is worth having.
Start seed early enough that seedlings are sturdy by planting-out time, but not so early that they go leggy indoors. Work backwards from your last frost using our seed-starting calculator, and confirm the timing with your local extension service — Zones 11–13 are frost-free, so the calendar there is about heat and rain rather than frost.
Seed germinates in 7–14 days but is famously unreliable, so many growers buy a nursery plant instead. If you do sow, give it steady warmth and do not let the mix dry out.
Transplanting and planting out
Set young plants out once the soil is workable, or after the last frost where the plant is tender. Handle the root ball gently, plant at the same depth as in the pot, and water in well.
Space plants 18–24 inches apart — crowding is one of the commonest causes of small harvests. Our plant-spacing calculator works out how many plants fit your bed. Harden seedlings off for a week before planting out, and plant on a cloudy day or in the evening so they do not wilt in their first hours outdoors.
Soil and feeding
Herbs mostly want lean, free-draining soil rather than rich ground — too much fertiliser makes soft, leggy growth with weak flavour. Dig in a little compost for structure and make sure water drains away freely, especially in winter.
Aim for a soil pH of 6.0–7.0 — a simple soil test will tell you where you stand. Feed lightly and steadily rather than in one heavy dose: too much fast nitrogen late in the season pushes leafy growth at the expense of the part you eat. Our fertiliser calculator works out amounts for your bed size, and the raised-bed soil calculator tells you how much mix a new bed needs.
Watering
Water needs are moderate: keep the soil evenly moist, watering deeply when the top inch or two dries out. Deep, infrequent watering builds deeper roots than a daily sprinkle.
Herbs in pots dry out faster than herbs in the ground, so check pots daily in hot weather. In the ground, most herbs are happy with a deep watering when the soil dries out rather than a daily sprinkle.
Water at the base of the plant, in the morning, so the leaves dry quickly. Our watering calculator gives a starting point for your bed size, and the watering schedule generator can build a routine around it.
Sunlight and temperature
Give herbs the sunniest spot you have — a south-facing bed, or a pot on a sunny step. Full sun keeps growth compact and flavour concentrated; in shade, most herbs grow leggy and taste weak.
This crop is rated tender for cold tolerance, so plan your season around that: hardy crops can be sown and harvested around frosts, while tender crops need warm soil and frost-free nights. Our sunlight calculator can check whether your spot gets enough sun, and the hardiness-zone finder will confirm your zone.
Pests and diseases
Stevia are not especially pest-prone when healthy and well placed, but a few pests turn up regularly. The ones listed for this crop in the growing data are aphids, slugs, thrips.
- Aphids — Small sap-sucking insects that cluster on soft new shoots, weakening growth. A strong jet of water dislodges them, and ladybirds usually keep them in check.
- Slugs — Slugs feed at night, chewing holes in leaves and fruit — especially young seedlings and berries at ground level. Hand-pick them after dark and keep the ground clear of hiding places.
- Thrips — Tiny insects that rasp at leaves and flowers, leaving silvery streaks and distorted growth. Worst in hot, dry weather; keep plants watered and remove damaged leaves.
Inspect plants weekly, especially the undersides of leaves, and act early. If you need help identifying what you are seeing, our pest-identifier helper and plant-disease checker walk through the symptoms.
Companion plants
Companion planting puts together plants that help each other — sharing space well, attracting pollinators, or confusing pests. The companions listed for stevia in the growing data are a good starting point.
Good companions for stevia include:
- Tomatoes
- Peppers
- Marigolds
- Cabbage
Our companion-planting finder can suggest more pairings for your bed plan.
Harvesting
Pick leaves just before the plant flowers, when they are at their sweetest — once it flowers, the leaves turn less sweet. Cut whole stems, strip the leaves, and dry them in a dark, airy place until crisp, then crumble and store in a jar.
Expect the crop to be ready about 90–120 days after sowing, though weather and variety shift that window by a week or two either way. Our harvest-date calculator works out your expected harvest date from your sowing date, and the vegetable-yield estimator can estimate how much a bed should produce. Harvest in the morning, using a sharp knife or secateurs rather than tearing, which damages the plant.
Common problems and fixes
| Problem | Likely cause | Fix |
|---|---|---|
| Poor germination | slow, unreliable seed | start with a nursery plant, or sow indoors with steady warmth |
| Wilting in dry spells | uneven watering | water deeply when the top inch or two dries out, and mulch |
| Aphids on the plants | aphids feeding on the crop | inspect weekly and act early — hand-pick, wash off, or use barriers |
Poor germination
Likely cause: slow, unreliable seed. Poor germination is the classic stevia frustration: seed is slow and unreliable, so many growers start with a nursery plant instead. Frost is the other killer — one cold night ends the plant, so have a pot ready to bring in or plan on replanting each spring.
Wilting in dry spells
Likely cause: uneven watering. A dry spell while fruit or flowers are forming costs you the crop. Water deeply when the top inch or two of soil dries out, and mulch to keep moisture even.
Aphids on the plants
Likely cause: aphids feeding on the crop. Small sap-sucking insects that cluster on soft new shoots, weakening growth. A strong jet of water dislodges them, and ladybirds usually keep them in check.
Frequently asked questions
How long does stevia take to germinate?
7–14 days, in warm, moist conditions. Cool soil slows germination down, so wait for the soil to warm up and keep the seedbed evenly moist — not wet — until seedlings appear.
What soil pH does stevia need?
A soil pH of 6.0–7.0 suits stevia best. A simple soil test will tell you where your soil stands, and lime or sulfur can nudge pH up or down over a season.
When can I harvest stevia?
About 90–120 days after sowing, though weather and variety shift that by a week or two. For nursery-grown plants the wait is shorter than for seed.
How do I use stevia leaves to sweeten tea?
Drop one or two fresh leaves into a cup of hot tea and let them steep for a few minutes, or dry the leaves, crumble them into a powder, and add a pinch at a time. The sweetness is intense, so use far less than you would sugar.