Stevia is the sweet-leaf plant: its leaves are intensely sweet, many times sweeter than sugar, and they are used fresh or dried to sweeten tea and cooking without calories. In Zone 10 it grows as a tender perennial, happiest in the warm months.
A word of honesty before you plant it: home-grown stevia leaves have a sweet taste with a liquorice-like aftertaste that some people love and others do not, and they do not behave exactly like sugar in baking. Grow a plant or two, try the leaves in tea first, and see whether you like it before planting a row.
Zone 10 at a glance
USDA Zone 10 covers the warmest parts of the United States — South Florida, the southernmost tip of Texas, coastal Southern California and Hawaii. Winters are mild, with average winter lows of 30 to 40°F, and the growing season runs nearly all year, with frost a rare event rather than a season marker.
The average last spring frost in Zone 10 is Jan 15–30, and the average first autumn frost is Dec 15–31 — and frost is rare in most Zone 10 gardens. These are USDA zone averages drawn from NOAA frost records, not exact dates for any one garden — always check your local extension service and the forecast before planting tender crops outside.
| Detail | Zone 10 guidance |
|---|---|
| Average winter low | 30 to 40°F |
| Average last spring frost | Jan 15–30 (frost rare; average/range) |
| Average first autumn frost | Dec 15–31 (frost rare; average/range) |
| Days to germination | 7–14 days |
| Days to maturity | 90–120 days |
| Sowing | start indoors |
| Sun | full sun |
| Soil pH | 6.0–7.0 |
| Spacing | 18–24 inches |
| Water needs | moderate |
| Cold tolerance | tender |
When to plant stevia in Zone 10
Plant stevia in Zone 10 from February through May, after the average last frost of Jan 15–30, from nursery plants or seed started indoors — seed takes 7–14 days to germinate and plants take 90–120 days to establish, and bought plants give you usable leaves much sooner. The average first autumn frost is Dec 15–31, and frost is rare, so stevia has a long warm season to grow. Wait until nights are reliably mild before planting out, since stevia is tender and cold checks its growth. In the mildest Zone 10 gardens it may survive winter; elsewhere, take cuttings in autumn to keep a plant going.
Work back from the frost dates rather than from a calendar date: the planting calendar hub gives the Zone 10 picture month by month. The month guides for March in Zone 10 and May in Zone 10 show what else is happening at planting time. The herb drying calculator can help you work out your exact sowing dates.
Starting stevia in Zone 10
Start stevia seed indoors in fine mix, sowing on the surface since the tiny seed needs light to germinate, and keep it moist for 7–14 days — germination can be patchy, so sow thickly. Or buy a nursery plant, which is the more reliable route. Transplant seedlings once they are sturdy, spacing them 18–24 inches apart in full sun and rich, moisture-holding soil. Water in well and keep young plants moist until established. Stevia grows well in pots, which makes it easy to move under cover if a rare cold night threatens.
Soil, spacing, sun and water
Stevia needs full sun in Zone 10 — in the hottest months a little afternoon shade keeps leaves tender and prevents scorch, but too much shade weakens flavour and growth. It grows best in soil with a pH of 6.0–7.0. Stevia likes rich, moisture-holding soil with a pH of 6.0–7.0. Dig in compost before planting, and mulch to hold moisture — stevia wilts fast if it dries out. Space plants 18–24 inches apart so air can move between them; crowded plants stay damp and invite disease in Zone 10 humidity. Water needs are moderate: keep the soil evenly moist, especially while plants are young and in warm weather, and mulch to hold moisture and keep roots cool. A raised bed or a pot with drainage holes is often the easiest way to get the drainage right, so work out how much mix a bed or container needs before you buy.
Companion planting
Good companions for stevia include tomatoes, peppers, marigolds, cabbage. Stevia grows well near tomatoes, peppers and cabbage, and it fits neatly at the edge of a sunny herb bed. Keep it where it gets regular water, since it is less drought-tolerant than Mediterranean herbs like rosemary and thyme. The March guide for Zone 10 in March shows what else is going in at the same time.
Our guide to when to plant borage in Zone 10 shows how to time a second crop alongside it. For comparison with a cooler zone, see when to plant stevia in Zone 9.
Pests and problems
The common pests to watch for with stevia are aphids, slugs, thrips. Aphids may gather on soft growth — wash them off with water. Slugs can nibble young leaves in damp weather, and thrips may mark the foliage. Stevia is generally trouble-free in Zone 10; cold and drying out cause more losses than pests, so water consistently and protect it from rare cold nights. Check the undersides of leaves weekly — most Zone 10 pest problems are small when caught early and much harder once they spread. Avoid spraying broad insecticides on herbs you plan to eat; a strong jet of water, hand-picking and encouraging ladybirds and other beneficial insects will deal with most outbreaks.
Harvest and storage
Start picking stevia leaves once plants are established, about 90–120 days after planting, and pick little and often through the warm season. The leaves are sweetest just before flowering, so that is the best time for a big harvest — cut whole stems, strip the leaves, and dry them in a warm, airy spot out of direct sun until crisp, then crumble them into a jar. Use dried leaves in tea, or grind them to a powder. Pinch out flower buds as they appear to keep the plant leafy and delay the bitter taste that comes with flowering.
Frequently asked questions
When should I plant stevia in Zone 10?
Plant from February through May, after the average last frost of Jan 15–30, from nursery plants or seed started indoors.
Is stevia perennial in Zone 10?
It is a tender perennial — it may survive mild winters, but cold can kill it, so many gardeners take cuttings in autumn as insurance.
How do I use stevia leaves?
Use them fresh or dried in tea, or dry and crumble them into a powder. They are intensely sweet with a liquorice-like aftertaste.
When are stevia leaves sweetest?
Just before flowering. Pinch out flower buds to keep the plant leafy, and harvest in bulk before it flowers.