Wisconsin’s short summer means lemon grass must be started indoors before transplanting after frost. Finding the best time to plant lemon grass in wisconsin is the key to growing this tropical herb successfully in your northern garden. Without proper timing, your lemon grass will struggle to mature before the first fall frost arrives.
Lemon grass is a warm-season plant native to tropical Asia. It needs heat, sun, and a long growing season to produce those thick, fragrant stalks you love for teas and cooking. In Wisconsin, you can’t just toss seeds in the ground in May and hope for the best. You need a plan.
This guide covers exactly when to start seeds, when to transplant outdoors, and how to extend your harvest window. You’ll also learn what to do if you miss the ideal planting window. Let’s get your lemon grass growing.
Understanding Wisconsin’s Growing Zones
Wisconsin spans USDA hardiness zones 3b in the north to 5b in the south. Lemon grass is perennial only in zones 9 and warmer, so it’s an annual here. Your local frost dates determine your planting calendar.
Most of Wisconsin sees its last spring frost between mid-May and early June. The first fall frost arrives between mid-September and early October. That gives you roughly 100 to 140 frost-free days. Lemon grass needs at least 100 days to reach harvestable size, so timing is tight.
Check your specific zip code’s average last frost date. Use that date as your anchor for all planting decisions.
Last Frost Date By Region
- Southern Wisconsin (Madison, Milwaukee): May 5–15
- Central Wisconsin (Stevens Point, Wausau): May 15–25
- Northern Wisconsin (Eau Claire, Superior): May 25–June 5
Your best time to plant lemon grass in wisconsin depends on these dates. You’ll start seeds indoors 8 to 10 weeks before your last frost. Then transplant after all danger of frost has passed.
Best Time To Plant Lemon Grass In Wisconsin
The best time to plant lemon grass in wisconsin is indoors in late winter or early spring. For most gardeners, that means starting seeds between March 1 and April 15. Then transplant outdoors after your last frost date, typically from late May to early June.
If you buy starter plants from a nursery, you can skip the indoor seed starting. But you still need to wait until the soil warms to at least 60°F before putting them outside. Cold soil stunts lemon grass growth and can kill young plants.
Indoor Seed Starting Timeline
- 8–10 weeks before last frost: Start seeds indoors in small pots or seed trays. Use a seed-starting mix, not garden soil.
- 4–6 weeks before last frost: Seedlings should have 2–3 true leaves. Transplant them into larger 4-inch pots.
- 1–2 weeks before last frost: Begin hardening off your plants. Move them outdoors for a few hours each day, increasing exposure gradually.
- After last frost: Transplant into your garden or a large container when nighttime temperatures stay above 50°F.
This schedule gives your lemon grass a strong head start. By the time summer heat arrives, your plants are already growing vigorously.
Direct Sowing: Is It Possible?
You can direct sow lemon grass seeds outdoors, but it’s risky in Wisconsin. The growing season is simply too short. Seeds need soil temperatures of 70°F to germinate reliably, which often doesn’t happen until June. That leaves only 90 days or less for growth.
If you want to try direct sowing, wait until soil temperatures reach 70°F. Use a soil thermometer to check. Then plant seeds 1/4 inch deep and keep the soil moist. You’ll likely get smaller plants with thinner stalks compared to indoor-started plants.
For best results, stick with indoor starting. It’s the only reliable way to get harvestable lemon grass in Wisconsin.
Choosing The Right Lemon Grass Variety
Not all lemon grass varieties perform equally in short summers. Some mature faster than others. Here are the best options for Wisconsin gardens.
Fast-Maturing Varieties
- East Indian Lemon Grass (Cymbopogon flexuosus): This is the most common culinary variety. It matures in 100–120 days and produces excellent stalks for tea and cooking.
- West Indian Lemon Grass (Cymbopogon citratus): Slightly slower to mature, but more cold-tolerant. Good for southern Wisconsin gardens with longer seasons.
- Citronella (Cymbopogon nardus): Grown more for mosquito repellent than cooking. It’s tough and handles cooler temps better than culinary varieties.
Stick with East Indian lemon grass for the best chance of a harvest before frost. It’s the most reliable choice for northern gardeners.
Where To Buy Seeds Or Plants
You can find lemon grass seeds at most garden centers or online. Starter plants are also available at nurseries in late spring. Look for healthy, green stalks with no yellowing or wilting.
If you buy starter plants, choose ones that are at least 6 inches tall. Smaller plants may not have enough time to mature before fall. Bigger plants give you a head start.
Preparing Your Garden For Lemon Grass
Lemon grass needs full sun and well-draining soil. It also needs plenty of space. Each plant can grow 3 to 4 feet tall and 2 to 3 feet wide in a single season.
Soil Requirements
- pH between 6.0 and 7.5
- Rich in organic matter
- Good drainage (no standing water)
- Warm soil (at least 60°F at planting time)
Amend your soil with compost or aged manure before planting. This gives your lemon grass the nutrients it needs for rapid growth. If your soil is heavy clay, consider raised beds or large containers instead.
Container Growing Options
Growing lemon grass in containers is a smart choice for Wisconsin gardeners. You can move pots indoors when frost threatens, extending your harvest by weeks. Use a 5-gallon pot for each plant. Make sure the pot has drainage holes.
Container-grown lemon grass also warms up faster than garden soil. You can start moving pots outdoors earlier in spring, as long as you bring them in at night if temps drop below 50°F.
Transplanting Lemon Grass Outdoors
Transplanting is a critical step. Do it too early and cold weather stunts growth. Do it too late and you lose precious growing days.
When To Transplant
Wait until nighttime temperatures are consistently above 50°F. For most of Wisconsin, that’s late May to early June. Check your local forecast and avoid transplanting before a cold snap.
Soil temperature matters too. Use a soil thermometer and wait until the soil at 4 inches deep reads at least 60°F. Cold soil slows root development and can cause transplant shock.
How To Transplant
- Harden off your seedlings over 7–10 days. Start with 1 hour outdoors in shade, then increase time and sun exposure daily.
- Choose a cloudy day or late afternoon for transplanting. This reduces stress on the plants.
- Dig holes 12 inches apart. Space rows 24 inches apart if planting multiple.
- Place each plant at the same depth it was in its pot. Firm the soil gently around the roots.
- Water thoroughly after planting. Keep the soil moist for the first week.
Mulch around the base of each plant with straw or shredded leaves. This keeps soil warm and moist, and suppresses weeds.
Caring For Lemon Grass Through The Season
Once your lemon grass is in the ground, consistent care is essential. Wisconsin summers can be hot and humid, which lemon grass loves. But you still need to water, feed, and protect your plants.
Watering Needs
Lemon grass likes consistent moisture. Water deeply once or twice a week, depending on rainfall. Aim for 1 to 2 inches of water per week. Container plants may need daily watering in hot weather.
Check soil moisture by sticking your finger 2 inches into the soil. If it feels dry, water. If it’s still damp, wait another day. Overwatering can cause root rot, especially in heavy soil.
Fertilizing Schedule
Lemon grass is a heavy feeder. Apply a balanced fertilizer (10-10-10) every 4 to 6 weeks during the growing season. Or use a slow-release organic fertilizer at planting time.
If you notice yellowing leaves, your plants may need nitrogen. Apply a liquid fish emulsion or compost tea for a quick boost. Stop fertilizing by late August to allow plants to harden off before frost.
Pest And Disease Management
Lemon grass is relatively pest-free in Wisconsin. Spider mites can appear during hot, dry spells. Rinse plants with a strong spray of water to dislodge them. Aphids may also show up, but they rarely cause serious damage.
Fungal diseases like rust can occur in humid conditions. Ensure good air circulation by spacing plants properly. Avoid overhead watering, which spreads spores. If rust appears, remove affected leaves and dispose of them in the trash, not compost.
Harvesting Lemon Grass In Wisconsin
You can start harvesting lemon grass once the stalks are at least 1/2 inch thick at the base. This usually happens 90 to 120 days after transplanting. In Wisconsin, that means harvest time is typically late August through September.
How To Harvest
- Choose stalks that are thick and firm. Avoid thin or woody stalks.
- Cut the stalk at ground level using a sharp knife or pruners.
- Remove the tough outer leaves. Use the tender inner part for cooking or tea.
- Leave at least half the stalks on each plant so it continues growing.
You can harvest multiple times from the same plant. Just don’t take more than one-third of the stalks at once. The plant needs leaves to keep photosynthesizing.
Extending The Harvest
If frost threatens before your lemon grass is fully mature, you can dig up the entire plant and bring it indoors. Pot it up and place it in a sunny window. It will continue growing for several more weeks.
You can also cut all the stalks at once and store them in the refrigerator. They’ll keep for 2 to 3 weeks. Or freeze chopped lemon grass in ice cube trays with water for longer storage.
Overwintering Lemon Grass Indoors
Lemon grass is a perennial in warm climates, but it can’t survive Wisconsin winters outdoors. However, you can overwinter a plant indoors and replant it next spring. This saves you from starting seeds again.
Steps For Overwintering
- Before the first frost, dig up a healthy plant or bring a container indoors.
- Cut the stalks back to 6 inches tall. Remove any dead or yellowing leaves.
- Pot the plant in fresh potting soil if it was in the ground. Use a pot with drainage holes.
- Place the pot in a bright, sunny window or under grow lights.
- Water sparingly during winter. Let the soil dry out between waterings.
- Fertilize once a month with a diluted houseplant fertilizer.
Your lemon grass will go semi-dormant during winter. Growth will slow, but the plant will survive. In spring, you can move it back outdoors after the last frost.
Common Mistakes And How To Avoid Them
Even experienced gardeners make mistakes with lemon grass in Wisconsin. Here are the most common problems and solutions.
Planting Too Early Outdoors
It’s tempting to put plants out in early May when the weather warms up. But a late frost can kill them. Always wait until after your last frost date, even if it feels safe. Use a frost blanket if you must plant early.
Not Hardening Off Seedlings
Moving indoor plants directly into full sun and wind shocks them. Leaves may turn white or brown. Always harden off gradually over 7–10 days. Start with a few hours of shade, then increase exposure.
Overwatering Or Underwatering
Lemon grass needs consistent moisture, but not soggy soil. Overwatering leads to root rot. Underwatering causes stunted growth and thin stalks. Check soil moisture regularly and adjust watering as needed.
Ignoring Frost Warnings
Early fall frosts can catch you off guard. Keep an eye on the weather forecast starting in mid-September. Have row covers or old sheets ready to protect your plants if frost is predicted. Or harvest everything before the frost hits.
Frequently Asked Questions
Can I Plant Lemon Grass From The Grocery Store In Wisconsin?
Yes, you can root grocery store lemon grass stalks in water. Look for stalks with the root end intact. Place them in a glass of water, change the water every few days, and wait for roots to appear. Then pot them up and grow indoors until after your last frost.
What Is The Latest I Can Plant Lemon Grass In Wisconsin?
The latest safe planting time is mid-June for southern Wisconsin and early June for northern areas. Planting later than that gives your plants less than 90 days to mature. You may still get some harvest, but stalks will be thin.
How Do I Know When My Lemon Grass Is Ready To Harvest?
Harvest when stalks are at least 1/2 inch thick at the base. The stalk should feel firm and solid, not soft or mushy. Leaves should be green and healthy. If stalks are thin and spindly, wait another week or two.
Can I Grow Lemon Grass In A Greenhouse In Wisconsin?
Yes, a greenhouse extends your growing season significantly. You can start seeds earlier in spring and harvest later into fall. Heated greenhouses allow year-round growth. Even an unheated cold frame can add 4 to 6 weeks to your season.
Why Is My Lemon Grass Not Growing Well?
Common reasons include insufficient sunlight, cold soil, poor drainage, or lack of nutrients. Lemon grass needs full sun (at least 6 hours daily), warm soil (above 60°F), and regular feeding. Check these factors and adjust accordingly.
Final Tips For Success
Growing lemon grass in Wisconsin is absolutly doable with the right timing. Start seeds indoors 8 to 10 weeks before your last frost. Transplant after the soil warms and all frost danger has passed. Provide full sun, consistent moisture, and regular fertilizer.
If you miss the ideal planting window, don’t give up. You can still buy starter plants from a nursery in late spring. Or try direct sowing in June, though results will be smaller. Container growing gives you flexibility to move plants indoors when weather turns cold.
Remember that lemon grass is a tropical plant. It thrives in heat and humidity. Wisconsin summers can deliver that, but only if you give your plants enough time. Start early, protect from cold, and you’ll be enjoying homegrown lemon grass tea and stir-fries by late summer.
Your first harvest might be small, but it will be rewarding. Each year you’ll get better at timing and care. Before long, you’ll have a reliable supply of fresh lemon grass for your kitchen. Happy growing.