Lemongrass grows well from seed if you give it warmth, light, and a head start indoors.
To grow lemongrass from seed, press the seeds onto the surface of moist seed-starting mix about 8 weeks before your last frost, keep them at 70 to 80°F until they sprout in one to three weeks, then plant the young clumps outside once nights stay above 60°F.
The seed is tiny and slow at first, and germination is often patchy. Once summer heat arrives, though, those thin blades turn into a big fountain of citrus-scented leaves.
With the right timing, you can be cutting leaves for tea by midsummer and pulling thick stalks for cooking by late summer.
Seed-to-Harvest Timeline at a Glance
Growing lemongrass from seed takes about four to five months from sowing to your first thick stalks, with leaf harvests starting sooner. Use this table to plan your weeks. If you are stocking up, a LED grow light is the first thing I would pick up.
If seeds feel slow, there’s a faster shortcut: you can root lemongrass stalks in a glass of water and have a plant ready to pot in a few weeks.
| Stage | When It Happens | What You Do |
|---|---|---|
| Sow seeds | About 8 weeks before last frost | Surface-sow on moist mix at 70 to 80°F |
| Germination | 1 to 3 weeks after sowing | Keep mix damp; add strong light once sprouts appear |
| Thin seedlings | When sprouts are about 1 inch tall | Snip extras, leaving small groups |
| Pot up clumps | 4 to 6 weeks after sowing | Move clumps to 3- or 4-inch pots |
| Harden off | 7 to 10 days before planting | Build up outdoor time slowly |
| Plant out | Nights stay above 60°F | Full sun, well-drained soil or a large pot |
| First leaf harvest | Plants reach 12 inches or taller | Snip outer blades for tea |
| First stalk harvest | Late summer | Cut outer stalks about 1/2 inch thick |
Harvesting lemongrass stalks takes the longest because the bases need hot weather to swell. In short-summer areas, expect thinner stalks the first year.
When Should You Start Lemongrass Seeds?
Start lemongrass seeds indoors about 8 weeks before your average last frost date. That gives seedlings time to form small clumps before nights warm up enough for planting.
Your region changes the calendar quite a bit, so set your date by your own frost dates and night temperatures.
Count Back Eight Weeks from Your Last Frost
Find your average last frost date, then count back 8 weeks on the calendar. That’s your sowing week.
If your last frost is May 10, sow around March 15. If it’s April 1, sow in early February.
I like the 8-week window because lemongrass seedlings grow slowly in their first month. Some seed packets suggest only 3 weeks, but that leaves you with tiny plants at planting time.
Starting too early has its own cost, since you’ll be growing lemongrass indoors under lights for months in cramped pots.
Keep in mind that your last frost date is a starting point. Lemongrass shouldn’t go outside until nights stay above 60°F, which in many places comes 2 to 4 weeks after the last frost.
Adjust the Schedule for Your US Region
Here’s how I’d time it in different parts of the country:
- Northeast and Midwest (zones 4 to 7): Sow mid-March to early April. Plant out in late May or early June, once nights hold above 60°F.
- Southeast (zones 7 to 9): Sow in late January or February. Plant out in April.
- Florida, South Texas, and Southern California (zones 10 to 11): Sow in late winter or early spring. Lemongrass is perennial here, so plants can stay in the ground for years.
- Southwest low desert: Sow in January and plant out by March, before the extreme heat. Afternoon shade helps young plants in summer.
- Pacific Northwest: Sow in early April. Cool nights last into June, so many gardeners keep plants in containers on a warm patio.
In zones colder than 9, you’ll treat lemongrass as an annual or bring it inside before nights drop below 50°F.
What You Need Before Sowing
You need fresh seed of the right species, a shallow tray, fine seed-starting mix, gentle bottom heat, and a strong light source. Getting these ready before sowing day keeps the tiny seeds from sitting in cold, dim conditions while you shop.
Choose Seeds Labeled with the Right Species
Check the botanical name on the packet. West Indian lemongrass, Cymbopogon citratus, is the classic cooking type with fat, tender stalk bases.
East Indian lemongrass, Cymbopogon flexuosus, is a close cousin. It’s a bit more compact and is often grown for oil, though its leaves still make good tea.
Many seed packets sold in the US are C. flexuosus, so read the label if thick stalks for cooking are your goal.
Buy seed packed for the current year. Lemongrass seed loses viability fairly fast, and old seed is one of the top reasons nothing sprouts.
Plan on low germination. Even fresh lemongrass seed often comes up at about 50%, so sow more than you think you need.
Set Up Trays, Seed-Starting Mix, Heat, and Light
Here’s my basic setup:
- Tray or cells: A shallow flat or 6-cell inserts with drainage holes, plus a clear humidity dome.
- Seed-starting mix: A fine, sterile mix. Skip garden soil, which crusts and carries disease.
- Seedling heat mat: This holds the mix near 75°F, which matters in cool basements or spring kitchens.
- Thermostat (optional): Plugs into the mat and stops it from overheating.
- LED grow light: A sunny window rarely gives enough light in March. A shop-style LED hung 2 to 4 inches above seedlings works well.
- Spray bottle: Misting keeps the seeds in place.
- Vermiculite (optional): A light dusting holds seeds steady.
- Labels: Write the species and sowing date.
Step 1: Sow Seeds on the Surface
Sow lemongrass seeds on top of the mix and press them in lightly, with no more than a thin dusting on top. Light helps these seeds germinate, so this is the step where most failures start.
If you’re learning how to grow lemongrass from seeds for the first time, get this part right and the rest gets easier.
Moisten the Mix and Press Seeds into Place
Wet the seed-starting mix before you sow. Squeeze a handful; it should hold together without dripping, like a wrung-out sponge.
Fill your cells or tray to about 1/4 inch from the top and firm the surface gently with your fingers.
Scatter lemongrass seeds thinly across the surface. Since the seed is so fine and germination is low, I’d drop 4 to 6 seeds in each cell.
Press the seeds down with a flat hand or the bottom of a cup so they touch the damp mix. Good contact lets them soak up water.
Mist the surface, set the dome on top, and label the tray.
Why a Deep Cover Can Prevent Sprouting
Lemongrass seeds are small and carry little stored energy. Buried at 1/4 inch, a sprout can run out of fuel before it reaches the surface.
Seed packets commonly list a depth of 1/16 inch, and some say no deeper than 1/8 inch. I press the seeds down and leave them uncovered.
If you want a cover, use a light sprinkle of vermiculite. It lets light through and keeps seeds from washing around when you water.
Step 2: Keep Seeds at 70 to 80°F and Evenly Moist
Lemongrass needs steady warmth between 70 and 80°F and a constantly damp surface to sprout. Seeds that cool down at night or dry out for even a day often stall. Bottom heat and a humidity dome handle both jobs with little effort.
Use Bottom Heat Without Overheating the Tray
Set the tray on a seedling heat mat. Most mats warm the mix about 10 to 20°F above room temperature, which is enough in a 60°F room.
Push a soil thermometer into one cell to check. You’re aiming for 70 to 80°F, with about 75°F as the sweet spot.
A thermostat controller keeps things steady. Without one, a mat in a warm room can push the mix into the high 80s and dry the surface fast.
Once most seedlings are up, turn the heat off or lower it. At that point, strong light helps them more than extra warmth.
Keep the Surface Damp, Not Soggy
The top layer, where the seeds sit, is the part that must never dry. Check it once or twice a day.
Mist when the surface looks lighter in color. Bottom watering also works: set the tray in an inch of water for 10 to 15 minutes, then drain it.
Avoid pouring water from a can. It washes tiny seeds into clumps or buries them.
Soggy mix starves the seeds of air and invites mold. If water beads on the inside of the dome all day, prop one corner open for an hour.
Step 3: Watch for Germination over One to Three Weeks
Most lemongrass seeds sprout in 7 to 21 days at the right temperature, and some trays take a little longer. Expect the first few to appear well before the rest, so stay patient.
What New Sprouts Look Like
New lemongrass seedlings look like fine green threads, thinner than a pencil lead. They’re easy to mistake for a blade of lawn grass or a mold strand.
Each sprout has a single narrow leaf. A second and third blade follow over the next couple of weeks.
As soon as the first sprouts show, take the dome off for part of the day and put the tray under your LED grow light. Seedlings that stay under a closed dome stretch and get weak.
How to Handle Uneven Emergence
Patchy germination is normal for lemongrass. You might see three sprouts in one cell and none in the next.
Keep the empty cells warm and moist for a full 3 weeks before giving up on them. Late seeds still make healthy plants.
If one cell is full and its neighbor is bare, leave both alone for now. You can tease apart and share a crowded group later when you pot up.
If almost nothing comes up after 3 weeks, check the troubleshooting tips further down before reseeding.