How to Propagate Lemongrass: Root Grocery Stalks in Water or Divide Your Plant
Propagate lemongrass from grocery stalks in 2–3 weeks or divide your plant in 5 steps. Zone-by-zone timing, troubleshooting, and after-care guide included.
A lemongrass stalk from the supermarket — the same one you’d buy for Thai soup — will grow into a full plant. Set it in a jar of water near a sunny window, and within two to three weeks in warm conditions you’ll see white roots pushing out from the base. No garden, no rooting hormone, no special equipment.
If you already have an established lemongrass clump, the second method is even faster: division. A mature clump produces 50 to 200 individual stems (called tillers), and separating them gives you several new plants in a single afternoon. Our lemongrass growing guide covers what to do once your new plants are established; this guide focuses entirely on getting them started reliably from both methods.
Why Lemongrass Propagates So Easily: The Tiller Biology
Lemongrass (Cymbopogon citratus) is a clump-forming grass that expands through underground rhizomes — horizontal stems that send up vertical shoots called tillers. Each tiller is structurally a complete plant. It has its own leaf sheaths and, critically, root-initiation tissue concentrated at the pale bulbous base — the meristematic cells that respond to the right conditions by generating a new root system from scratch.
This is why a detached stalk with no roots attached will still root in water: the base tissue already has everything it needs. When that base sits in contact with water, auxin (the plant’s primary rooting hormone) accumulates at the base and triggers adventitious root formation from those undifferentiated cells. According to UW-Madison Horticulture Extension, dense lemongrass clumps can reach 6 feet in diameter and each stem arises from a short, ringed rhizome — meaning the root initiation mechanism is built into the plant’s architecture.
The intact bulb base is therefore the single non-negotiable requirement. A stalk with the base cleanly trimmed off, dried brown, or collapsed won’t root regardless of how long you wait. Everything else — water temperature, light levels, timing — affects speed, not whether it works at all.
Method 1: Water-Rooting Grocery Store Stalks
This method works whether you’re starting from scratch or want to multiply a plant before dividing an established clump.
Selecting the Right Stalks
The bottoms of grocery store lemongrass stalks are often trimmed for packaging. Your first job is identifying which ones still have a viable base.
A rootable stalk has a pale (white to light green) bulbous base at least ½ inch in diameter, firm texture throughout, and at least 4 inches of total length. Avoid stalks where the base is brown, hollow, spongy, or completely flat-cut. In practice, the base condition is a more reliable predictor than overall stalk freshness — a slightly wilted top won’t stop rooting, but a soft or trimmed base will, no matter how long you wait. Illinois Extension confirms that grocery store lemongrass “can often be rooted,” but success depends entirely on the base being intact.
Buy at least 5–6 stalks. Not every stalk will root even if selected carefully — starting with extras ensures you end up with enough plants without a second trip to the store.
Preparation
Peel back 1–2 outer layers from each stalk to expose the clean pale base. Trim any dried brown tops where the leaf blades split. Do not trim the base itself.
The Water Setup
Stand stalks bulb-down in a jar with about 1 inch of water — enough to cover the base without submerging the green upper portion. Place in the sunniest spot available: a south- or west-facing windowsill is ideal. Lemongrass is a tropical C4 grass; warmth and high light directly accelerate root formation.
Change the water every 1–2 days without exception. This is not optional maintenance — stagnant water turns anaerobic within 48 hours, and anaerobic conditions destroy developing root primordia before they emerge as visible roots. Daily changes are better than every two days, especially in warm weather.
Rooting Timeline by Temperature
Temperature is the biggest variable most guides skip. The same stalk that roots in three weeks on a summer windowsill can take two months or more in winter, when a windowsill might stay below 65°F during the day.
| Condition | Rooting time | What appears first |
|---|---|---|
| Warm (75°F+) | 2–3 weeks | New leaf growth at top within 3–7 days |
| Moderate (65–74°F) | 3–5 weeks | Slower leaf emergence; roots by week 4–5 |
| Cool (below 65°F) | Up to 2 months | Very slow; possible failure if below 55°F |
In winter, a seedling heat mat under the jar — set to 75°F — reliably closes this gap. Garden Betty’s propagation guide notes the same seasonal difference: summer takes around 3 weeks while winter propagation can stretch to 2 months in an unheated room.
When to Transplant
Transplant when roots reach 1–2 inches long. For better odds of a smooth transition, wait until at least one offshoot stalk has emerged at the base — this confirms a functional root system is in place, not just the earliest root primordia.
Plant crown-deep in rich, loamy, well-draining soil in a full-sun location. “Full sun” for lemongrass means 6+ hours of direct sun daily — not bright shade. Plants in lower light establish slowly and produce thin, poor-quality stalks.
Method 2: Dividing an Established Plant
Division is the most reliable propagation method for lemongrass and also a necessary maintenance step. Potted plants need dividing every 12–18 months; in-ground clumps every 1–2 years.
Signs Your Plant Is Ready
You don’t need to wait for problems — annual division keeps lemongrass productive. These signs mean it’s overdue:
- Dead or hollow center: The outer ring of tillers takes over while the inner core dies back. The clump looks full from the outside but collapses in the middle.
- Noticeably thinner or shorter new stalks: Crowded tillers compete for the same root zone and water supply.
- Roots emerging from drainage holes: In containers, this means the root ball has filled the pot and has nowhere left to go.
When to Divide
Divide in spring to early summer, once temperatures are reliably above 50°F after your last frost date. This gives divisions the longest possible warm growing season to re-establish. In mild climates (zones 8–9), early autumn also works if you can allow 6 weeks of warm weather before temperatures drop.
Tools and Safety
Wear long gloves — lemongrass leaf edges are sharp enough to cut skin. You’ll need a sharp spade, bread knife, or garden saw to cut through the dense root mat. Tearing divisions apart (rather than cutting) damages significantly more roots and delays re-establishment.
Division Steps
- Water thoroughly the day before. Moist roots hold together better and recover faster than dry ones.
- Cut foliage back to 6–10 inches. This reduces water loss while the division is establishing and makes the clump easier to handle.
- Dig 6 inches out from the base to loosen the root ball, then lift the entire clump out of the ground or pot.
- Cut into sections, each containing 3–5 healthy stalks with a substantial root portion attached. At least 1 inch of root per section is the minimum for reliable re-establishment.
- Replant immediately with crowns at soil level. Don’t let roots dry out between cutting and replanting — even 20 minutes of air exposure in warm conditions can set back establishment.
Spacing and Container Sizing
In-ground: space divisions 18–24 inches apart. Lemongrass clumps grow 3 feet wide at maturity, and crowded plants produce fewer and smaller stalks. Containers: use a pot at least 12 inches wide and deep per division. For a plant you intend to harvest stalks from regularly, a 5-gallon container is the practical minimum.
Post-Division Care
Keep soil consistently moist (not waterlogged) for the first 2 weeks. Move divisions to a shaded or semi-shaded spot for 7–10 days while roots re-establish — a shade cloth works well for in-ground divisions. Apply a diluted general-purpose liquid fertilizer starting 2 weeks after dividing. Expect visible new growth within 3–4 weeks and resume harvesting once 4–6 weeks of active growth have occurred.
Timing by USDA Zone
| Zone | Lemongrass status | Best propagation window | Notes |
|---|---|---|---|
| 9–11 | Perennial | Spring or autumn | Division or grocery stalks both work year-round |
| 7–8 | Marginal perennial | Late spring | Start stalks in water in April–May; divide after last frost |
| 5–6 | Annual | Start indoors 4–6 weeks before last frost | Move outdoors when nights stay above 50°F |
| Any zone | Indoor year-round | Any time | Use a heat mat to maintain 75°F at the jar base |
Overwintering Propagation Material (Zones 7 and Below)
In cold climates, lemongrass dies to the ground after frost — but you don’t need to buy new stalks every spring. Before your first frost date, cut the plant back to 6 inches and dig it up. USU Extension specifically recommends saving a 6-inch section of the bulbous shoot base with attached roots, potted in a small container and moved indoors to a bright spot. Water sparingly through winter while the plant is dormant.
In early spring — 8–10 weeks before last frost — move the pot to warmth and resume regular watering. The saved section will sprout new tillers. Once active growth begins, you can separate the emerging tillers individually and root or pot them as new plants, giving you multiple starts from one preserved section. This makes lemongrass self-perpetuating in cold climates without buying grocery stalks every year.
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→ View My Garden CalendarTroubleshooting
| Problem | Cause | Fix |
|---|---|---|
| Stalk base turns brown or slimy in water | Water not changed often enough; anaerobic conditions | Change water daily; discard brown-based stalks; start with fresh ones |
| No roots after 3+ weeks in warm conditions | Base too trimmed, dried, or damaged before purchase | Select new stalks; buy 5+ extras to ensure enough viable bases |
| New leaves emerge but no roots form | Temperature at base too low; jar in indirect light | Add heat mat under jar; move to a brighter, warmer window |
| Division wilts badly after transplanting | Root disturbance; too much direct sun immediately after | Shade for 7–10 days; water consistently; wilting is normal for 1–2 weeks |
| Division produces only thin new stalks | Division too small; fewer than 3 stalks or minimal roots | Ensure at least 3–5 stalks per division with a substantial root section |
| Rooted stalk dies after transplanting from water | Overwatered in soggy soil; poor drainage | Use well-draining loamy mix; water moderately for first 2 weeks only |
After-Care for New Plants
Both methods produce plants with identical care requirements once established:
- Sun: 6+ hours of direct sun daily. Lemongrass in part shade produces fewer and thinner stalks.
- Water: Keep soil consistently moist in dry weather. Lemongrass needs more water than most herbs — UW-Madison Extension describes it as requiring “a great deal of water.”
- Fertilizer: Apply a general-purpose liquid fertilizer every two weeks from June through September. Stop fertilizing once temperatures drop in autumn.
- Harvest timeline: First stalks are ready to cut when they reach 12 inches tall — typically 2–4 months after propagation. For indoor growing through winter or container management year-round, see our guide to growing lemongrass indoors.
Frequently Asked Questions
Do I need rooting hormone for lemongrass?
No. The bulb base already contains the meristematic cells needed for root formation. Rooting hormone won’t hurt, but extension sources don’t recommend it as necessary for this species.
How many plants will one grocery bundle give me?
A typical bundle has 5–8 stalks. Expect a 50–70% rooting success rate depending on stalk quality and temperature. Buy 6 stalks to reliably get 3–4 rooted plants.
Can I propagate lemongrass in winter?
Yes, but expect 6–8 weeks rather than 2–3. A seedling heat mat under the jar, keeping the water at 75°F, brings winter rooting times close to summer rates.
How often should I divide lemongrass in a pot?
Every 12–18 months. Potted lemongrass becomes root-bound faster than in-ground plants — you’ll see thinner stalks and roots pushing out of the drainage holes when it’s time. For what to do with the culinary harvest from freshly divided stalks, see the guide to lemongrass uses in cooking and tea.
