Illinois residents find success starting lemongrass indoors six weeks before their last spring frost date, then transplanting in late May. Knowing the best time to plant lemon grass in illinois is crucial because this tropical plant hates cold weather and needs warm soil to thrive. If you plant too early, frost will kill it. Plant too late, and it won’t have enough time to grow before fall cools down.
Lemongrass is a fantastic herb for cooking teas and adding a citrusy flavor to dishes. It also works as a natural mosquito repellent in your garden. But in Illinois, with its cold winters and unpredictable springs, timing is everything.
This guide will walk you through the exact steps and schedules for planting lemongrass in Illinois. We will cover indoor starting, transplanting, and direct sowing. You will learn how to work with your local frost dates and soil temperatures.
Best Time To Plant Lemon Grass In Illinois
The absolute best window for planting lemongrass in Illinois is from late May to early June. This timing applies to both transplants you started indoors and store-bought plants. The soil needs to be consistently above 60°F (15°C) before you put lemongrass outside.
Illinois spans USDA hardiness zones 5a in the north to 7a in the south. This means your exact planting date will vary by about two to three weeks. Northern Illinois gardeners near Chicago should aim for late May or early June. Southern Illinois growers near Cairo can plant as early as mid-May.
Lemongrass is not frost-tolerant at all. A single light frost in spring will turn your plants brown and mushy. So you must wait until all danger of frost has passed. Check your local frost date for your specific county.
Understanding Illinois Frost Dates
Your last spring frost date is the key to planning. Here are approximate dates for different regions of Illinois:
- Northern Illinois (Chicago, Rockford): Last frost around April 20 to May 10
- Central Illinois (Peoria, Springfield): Last frost around April 10 to April 30
- Southern Illinois (Carbondale, Cairo): Last frost around March 30 to April 15
Wait at least two weeks after your last frost date before transplanting lemongrass. This buffer ensures the soil has warmed up enough. Cold soil below 60°F will stunt growth and may cause root rot.
Soil Temperature Requirements
Lemongrass is a tropical grass native to warm climates. It needs soil temperatures between 65°F and 85°F for optimal growth. You can measure soil temperature with a simple soil thermometer inserted two inches deep.
In Illinois, soil reaches 60°F consistently around late May in most areas. Southern Illinois may reach this temperature by mid-May. Northern Illinois often waits until early June. Do not rush this step.
If you plant in cold soil, the lemongrass will sit there and not grow. It may even rot. Patience pays off with faster, healthier growth later in the season.
Starting Lemongrass Indoors In Illinois
Because Illinois has a short growing season for tropical plants, starting lemongrass indoors gives you a head start. You can begin six to eight weeks before your last frost date. This means starting seeds or stalks indoors around mid-March to early April.
How To Start Lemongrass From Stalks
Most gardeners start lemongrass from grocery store stalks. This method is faster than seeds and more reliable. Here is how to do it:
- Buy fresh lemongrass stalks with the bulbous base still attached
- Trim off the top leafy part, leaving about 4 inches of stalk
- Place the stalks in a glass of water with the base submerged
- Change the water every two days to prevent bacteria growth
- Place the glass in a warm spot with indirect sunlight
- Roots will appear in 1 to 2 weeks
- Once roots are 1 inch long, transplant into small pots with potting soil
Keep the pots indoors near a sunny window or under grow lights. Water regularly but do not let the soil become soggy. Lemongrass likes moisture but not standing water.
Starting Lemongrass From Seeds
Seeds take longer and have lower germination rates. If you choose seeds, start them 8 to 10 weeks before your last frost. Sow seeds 1/4 inch deep in seed-starting mix. Keep the soil warm at 70°F to 75°F.
Germination can take 10 to 21 days. Be patient. Once seedlings have two sets of true leaves, transplant them into individual pots. Harden them off slowly before moving outside.
Hardening Off Your Lemongrass
Before transplanting outdoors, you must harden off your plants. This process takes about 7 to 10 days. Start by placing them outside for 1 hour in a shaded, protected spot. Gradually increase time and sun exposure each day.
Bring them indoors at night if temperatures drop below 50°F. After a week, they should be ready for full sun and outdoor conditions. This step reduces transplant shock and prevents sunburn.
Transplanting Lemongrass Outdoors In Illinois
Transplant your lemongrass outdoors in late May or early June. Choose a sunny location that gets at least 6 to 8 hours of direct sunlight daily. Lemongrass loves heat and will grow slowly in shade.
Preparing The Garden Bed
Lemongrass needs well-draining soil rich in organic matter. Illinois clay soil can be heavy, so amend it with compost or aged manure. Work the soil to a depth of 8 to 10 inches.
Test the soil pH. Lemongrass prefers a pH between 6.0 and 7.5. Most Illinois soil falls within this range, but it is worth checking. Add lime if your soil is too acidic.
Space plants 24 to 36 inches apart. Lemongrass grows into large clumps, up to 4 feet tall and 3 feet wide. Give them room to spread. Crowded plants produce smaller stalks.
Planting Steps
- Dig a hole twice as wide as the root ball
- Place the plant at the same depth it was growing in the pot
- Backfill with soil and gently firm around the base
- Water thoroughly after planting
- Apply a 2-inch layer of organic mulch around the base
- Keep the soil moist for the first two weeks
Water deeply once or twice a week, depending on rainfall. Lemongrass is somewhat drought-tolerant once established, but regular watering produces better growth. Do not let the soil dry out completely.
Direct Sowing Lemongrass In Illinois
Direct sowing lemongrass seeds outdoors is risky in Illinois. The growing season is short, and seeds need warm soil to germinate. However, you can try it in southern Illinois if you plant in late May.
If you want to direct sow, wait until soil temperature reaches 70°F. This usually happens in early June in central Illinois and late May in southern Illinois. Northern Illinois gardeners should stick to transplants.
Sow seeds 1/4 inch deep and keep the soil consistently moist. Germination will be slow. Thin seedlings to 24 inches apart once they are 4 inches tall. Expect a later harvest compared to transplants.
Caring For Lemongrass Through The Illinois Summer
Lemongrass grows quickly in hot weather. Illinois summers can be humid and warm, which lemongrass loves. With proper care, you can harvest stalks from July until the first frost in October.
Watering And Fertilizing
Water lemongrass deeply once a week if there is no rain. During heat waves, water twice a week. The soil should feel moist but not waterlogged. Overwatering can cause root rot in heavy clay.
Fertilize every 4 to 6 weeks with a balanced fertilizer like 10-10-10. You can also use compost tea or fish emulsion. Stop fertilizing in late August to allow plants to slow down before winter.
Harvesting Lemongrass
You can start harvesting when stalks are at least 1/2 inch thick at the base. Cut stalks at ground level using sharp shears. Remove outer leaves and use the tender inner part for cooking.
Harvest regularly to encourage new growth. Do not take more than one-third of the plant at a time. Leave enough foliage for photosynthesis. The plant will keep producing until frost.
Pest And Disease Management
Lemongrass is relatively pest-free in Illinois. Occasionally, spider mites or aphids may appear. Spray them off with a strong stream of water. Neem oil works for severe infestations.
Root rot is the main disease risk. Ensure good drainage and avoid overwatering. If you see yellowing leaves, reduce watering. Fungal leaf spots can occur in humid weather but rarely harm the plant.
Overwintering Lemongrass In Illinois
Lemongrass is perennial in zones 9 and above. In Illinois, it will not survive winter outdoors. You have two options: treat it as an annual or overwinter it indoors.
Bringing Lemongrass Indoors For Winter
Before the first frost in October, dig up a few clumps. Cut back the leaves to about 6 inches tall. Plant them in large pots with fresh potting soil.
Place the pots in a sunny window or under grow lights. Water sparingly during winter, allowing the soil to dry slightly between waterings. The plant will go semi-dormant and need less care.
In spring, you can replant the pots outdoors after the last frost. This method saves you from buying new plants each year. You can also divide the clumps to make more plants.
Storing Lemongrass Stalks
If you do not want to keep the plant alive, harvest all stalks before frost. Store fresh stalks in the refrigerator for up to 2 weeks. You can also freeze them for longer storage.
To freeze, chop the stalks into small pieces and place them in a freezer bag. Frozen lemongrass retains its flavor for 6 months. Dry lemongrass by hanging bundles in a warm, dark place.
Regional Variations Within Illinois
Illinois is a long state with different climates. Your exact planting schedule depends on where you live. Here are specific tips for each region.
Northern Illinois
Gardeners in Chicago, Rockford, and the northern suburbs have the shortest growing season. Start lemongrass indoors by March 15. Transplant outdoors around June 1 to June 10.
Use black plastic mulch to warm the soil faster. Cover plants with row covers if a late frost threatens. Choose fast-growing varieties like East Indian lemongrass.
Central Illinois
Central Illinois includes Peoria, Springfield, and Bloomington. Start seeds indoors by April 1. Transplant outdoors around May 20 to May 30. Soil warms up faster here than in the north.
You can direct sow seeds in early June if you want. But transplants still give you a better harvest. Water regularly during summer heat waves.
Southern Illinois
Southern Illinois has the longest growing season. Start seeds indoors by March 1. Transplant outdoors as early as May 10 to May 20. You may even get a second harvest in September.
Direct sowing is possible in late May. Lemongrass grows large here, often reaching 5 feet tall. Harvest heavily before the first frost in late October.
Common Mistakes To Avoid
Many Illinois gardeners make these mistakes when planting lemongrass. Avoid them for better success.
- Planting too early – Do not be tempted by warm days in April. Soil is still cold.
- Overwatering – Lemongrass likes moisture but not soggy roots. Clay soil holds water.
- Underestimating size – Lemongrass grows huge. Give it space.
- Ignoring frost warnings – Cover plants or bring pots inside if frost is predicted.
- Not hardening off – Indoor plants need gradual exposure to outdoor conditions.
Another common error is planting lemongrass in full shade. It will survive but produce thin, weak stalks. Full sun is essential for robust growth.
Frequently Asked Questions
Can I plant lemongrass in Illinois in July?
You can, but it is not ideal. July planting gives the plant less time to mature before frost. You may get a small harvest. Stick to late May or early June for best results.
Does lemongrass come back every year in Illinois?
No, lemongrass is not winter-hardy in Illinois. It will die if left outside during winter. You must bring it indoors or treat it as an annual.
What is the last frost date for Chicago?
Chicago’s average last frost date is around April 20 to May 10. Check your specific neighborhood, as urban areas may be warmer. Wait two weeks after this date to plant lemongrass.
Can I grow lemongrass in a container in Illinois?
Yes, container growing is excellent for lemongrass. Use a pot at least 12 inches wide. Bring the container indoors before frost. This makes overwintering easier.
How long does lemongrass take to grow in Illinois?
From transplanting, lemongrass takes about 60 to 90 days to reach harvest size. Starting indoors gives you a head start. You can harvest from July until frost.
Final Tips For Success
Planting lemongrass in Illinois requires timing and care. Start indoors to beat the short season. Wait for warm soil before transplanting. Give your plants plenty of sun and space.
Harvest regularly to keep plants productive. Overwinter a few clumps indoors to save money next year. With these steps, you can enjoy fresh lemongrass all summer long.
Remember that the best time to plant lemon grass in illinois is late May to early June. This timing works for transplants and store-bought plants. Do not rush the season. Your patience will be rewarded with healthy, flavorful lemongrass.
If you follow this guide, you will have success growing lemongrass in any part of Illinois. The key is knowing your local frost dates and soil temperatures. Plan ahead, start indoors, and enjoy the harvest.