Colorado gardeners face unique challenges when growing lemon balm, as the state’s dramatic temperature swings and short growing season demand precise timing for successful establishment. Understanding the best time to plant lemon balm in Colorado is crucial for getting this aromatic herb to thrive in your garden. Whether you are a beginner or an experienced grower, timing your planting correctly can make the difference between a lush harvest and a disappointing failure.
Lemon balm is a hardy perennial that can tolerate some cold, but Colorado’s unpredictable weather—including late spring frosts and early autumn chills—requires careful planning. The key is to align your planting with the window when soil temperatures are warm enough and the risk of frost is minimal. This article will guide you through the exact timing, methods, and tips to ensure your lemon balm flourishes in the Centennial State.
Best Time To Plant Lemon Balm In Colorado
The ideal window for planting lemon balm in Colorado is from late May to early June, after the last frost date has passed and soil temperatures have warmed to at least 60°F. This timing applies to both transplants and direct seeding, though transplants offer a head start in our short growing season. For most of Colorado, the last frost occurs between mid-May and late May, depending on your elevation and microclimate.
If you live in lower elevations like Denver or Colorado Springs, you can safely plant around May 20th. Higher elevations, such as the mountains or foothills, may need to wait until early June. Always check your local frost dates and monitor soil temperature with a simple thermometer before planting.
Starting seeds indoors 6-8 weeks before the last frost is a smart strategy. This gives your plants a strong start and allows you to transplant them at the optimal time. For Colorado, that means starting seeds indoors around late March or early April.
Understanding Colorado’s Growing Zones
Colorado spans USDA hardiness zones 3 through 7, with most of the Front Range falling in zones 5 and 6. Lemon balm is hardy to zone 4, so it can survive winters in most parts of the state with proper care. However, the planting window shifts based on your specific zone:
- Zone 3-4 (mountains, high valleys): Plant in early June, after all frost danger.
- Zone 5 (Denver, Boulder): Plant from mid-May to late May.
- Zone 6 (Colorado Springs, lower elevations): Plant from early May to mid-May.
- Zone 7 (southern Colorado, Arkansas Valley): Plant from late April to early May.
Remember that microclimates matter. A south-facing slope warms faster than a north-facing one. Your garden’s specific conditions may allow for slightly earlier or later planting.
Soil Preparation For Lemon Balm
Lemon balm prefers well-draining soil with a pH between 6.0 and 7.5. Colorado’s soil is often alkaline and clay-heavy, so amending it before planting is essential. Work in 2-3 inches of compost or aged manure to improve drainage and fertility. If your soil is very heavy clay, consider raised beds or containers.
Test your soil pH with a simple kit from a garden center. If it’s above 7.5, add sulfur or peat moss to lower it slightly. Lemon balm is forgiving, but it grows best in slightly acidic to neutral soil.
Clear the area of weeds and rocks. Lemon balm can spread aggressively, so consider planting it in a contained bed or using barriers to prevent it from taking over your garden.
Starting Seeds Indoors
For Colorado gardeners, starting lemon balm seeds indoors is the most reliable method. Here’s a step-by-step guide:
- Fill seed trays or small pots with a sterile seed-starting mix.
- Sow seeds 1/4 inch deep, covering lightly with soil.
- Water gently and cover with plastic wrap to retain moisture.
- Place in a warm location (70°F) with bright, indirect light.
- Seeds germinate in 10-14 days. Remove plastic once sprouts appear.
- Thin seedlings to one per pot when they have two sets of true leaves.
- Harden off seedlings by gradually exposing them to outdoor conditions over 7-10 days before transplanting.
Start this process 6-8 weeks before your planned outdoor planting date. For most Coloradans, that means starting seeds in early April.
Transplanting Outdoors
Transplant your hardened-off seedlings into the garden after the last frost. Choose a location with full sun to partial shade. In Colorado’s intense sun, afternoon shade can prevent leaf scorch. Space plants 18-24 inches apart to allow for their spreading habit.
Dig holes slightly larger than the root ball. Place the plant at the same depth it was in the pot. Backfill with soil and water thoroughly. Mulch around the base with straw or wood chips to retain moisture and regulate soil temperature.
Water deeply once a week, more often during hot, dry spells. Lemon balm likes consistent moisture but not waterlogged soil. Colorado’s dry climate means you may need to water every 2-3 days during summer heat waves.
Direct Sowing In The Garden
If you prefer direct sowing, wait until soil temperatures reach 60°F. In Colorado, this typically happens in late May or early June. Sow seeds 1/4 inch deep and 12 inches apart. Thin seedlings to 18-24 inches apart once they emerge.
Direct sowing is riskier in Colorado due to unpredictable frosts and dry soil. Keep the seedbed consistently moist until germination. Cover with row covers if a late frost threatens.
This method works best in warmer parts of the state, like the Front Range or lower elevations. In mountain areas, direct sowing often fails due to short growing seasons.
Fall Planting Considerations
Lemon balm can be planted in early fall, but this is riskier in Colorado. The plant needs at least 6-8 weeks to establish before the first hard frost. For most of the state, that means planting by mid-August to early September.
Fall-planted lemon balm may not survive winter if it hasn’t developed a strong root system. Mulch heavily with straw or leaves after the ground freezes to protect the roots. In colder zones, fall planting is not recommended.
If you want to try fall planting, choose a protected location and use a cold frame or cloche for extra protection. Even then, success is not guaranteed.
Container Planting For Flexibility
Growing lemon balm in containers gives you more control over timing and conditions. You can move pots indoors or to a sheltered spot if frost threatens. This is ideal for Colorado’s unpredictable weather.
Use a pot at least 12 inches in diameter with drainage holes. Fill with a quality potting mix. Plant seeds or transplants at the same depth as in-ground planting. Water more frequently, as containers dry out faster.
You can start container plants earlier in spring by moving them outdoors during the day and indoors at night. This extends your growing season significantly.
Care After Planting
Once your lemon balm is in the ground, proper care ensures a healthy harvest. Water regularly, especially during dry spells. Fertilize lightly with a balanced organic fertilizer once a month during the growing season.
Prune regularly to encourage bushy growth. Harvest leaves as needed, cutting stems above a leaf node. This prevents the plant from becoming leggy and promotes more foliage.
Watch for pests like aphids or spider mites, which can be washed off with a strong spray of water. Lemon balm is generally pest-resistant, but Colorado’s dry air can stress plants, making them more susceptible.
Winter Protection
Lemon balm dies back to the ground in winter but regrows from the roots in spring. In Colorado, protect the root zone with a thick layer of mulch after the first hard freeze. This insulates the roots from temperature fluctuations.
In colder zones (3-4), consider digging up a few plants and overwintering them indoors in pots. This ensures you have plants ready for next spring. In milder zones, mulch alone is usually sufficient.
Remove mulch in early spring when new growth appears. Be patient—lemon balm is often slow to emerge in Colorado’s cold springs.
Common Mistakes To Avoid
- Planting too early: Frost kills young plants. Wait until soil is warm.
- Overwatering: Lemon balm hates soggy roots. Let soil dry slightly between waterings.
- Ignoring sun exposure: Too much afternoon sun can scorch leaves. Provide some shade.
- Allowing it to spread: Lemon balm is invasive. Contain it with barriers or pots.
- Forgetting to harden off: Transplants need gradual acclimation to outdoor conditions.
Harvesting And Using Lemon Balm
You can start harvesting once the plant has at least 6-8 leaves. Pick leaves in the morning after dew dries for the best flavor. Use fresh in teas, salads, or as a garnish. Dry leaves for later use by hanging bundles upside down in a dark, airy place.
Lemon balm has a mild lemon flavor with hints of mint. It’s excellent for calming teas, adding to fruit salads, or infusing vinegar. The leaves can also be frozen in ice cubes for summer drinks.
Regular harvesting encourages more growth. Don’t remove more than one-third of the plant at a time to avoid stressing it.
Frequently Asked Questions
Can I Plant Lemon Balm In Colorado In The Fall?
Fall planting is possible but risky. Plant by mid-August to early September to give roots time to establish before frost. Heavy mulching is essential for winter survival.
What Is The Best Month To Plant Lemon Balm In Colorado?
Late May to early June is ideal for most of Colorado. This timing avoids frost and ensures warm soil for quick establishment.
Does Lemon Balm Come Back Every Year In Colorado?
Yes, lemon balm is a perennial that returns each year in zones 4-7. With proper winter protection, it survives Colorado’s cold winters and regrows in spring.
How Long Does Lemon Balm Take To Grow From Seed In Colorado?
Seeds germinate in 10-14 days indoors. From transplanting, you can harvest leaves in about 4-6 weeks. Direct-sown seeds take longer due to slower outdoor germination.
Can I Grow Lemon Balm Indoors In Colorado Year-round?
Yes, lemon balm grows well indoors with bright light and consistent moisture. Use a south-facing window or grow lights. It’s a great option for winter gardening.
Final Tips For Success
Timing is everything when growing lemon balm in Colorado. Stick to the late spring window for the best results. Start seeds indoors to get a jump on the season. Prepare your soil well and provide consistent care.
Remember that lemon balm is forgiving and adaptable. Even if you plant a bit late, it will likely still grow, though harvests may be smaller. The key is to avoid frost and give it enough time to establish before winter.
With the right timing and a little patience, you’ll enjoy fresh lemon balm from your Colorado garden all summer long. Happy planting!