How to Grow Lemon Basil Indoors & Outdoors (Full Guide)

If you’re looking for a refreshing, citrus-scented twist to your herb garden, lemon basil (Ocimum × citriodorum) might just be your new favorite green companion. I grow this beauty year-round in my windowsill garden, and it never ceases to amaze me how much flavor and vitality it brings to my kitchen and mood.

In this article, I’ll guide you through a science-backed roadmap to grow lemon basil indoors and outdoors. We’ll cover everything from seed germination to harvesting, so your plant thrives and your cooking flourishes.

What Is Lemon Basil?

Lemon basil is a hybrid herb, a cross between sweet basil and American basil, known for its lemon-scented leaves, faster growth cycle, and lighter green coloration.

Unlike its cousin Thai basil, lemon basil carries a zingy aroma due to high concentrations of citral and limonene, compounds responsible for its unique citrusy flavor.

Related Reading: Different Types of Basil

Why Grow Lemon Basil?

This herb is more than just a pretty leaf:

• Culinary uses: Elevates salads, teas, marinades, and pastas.
• Health benefits: Contains antioxidants and essential oils with antimicrobial properties (source).
• Indoor friendliness: Thrives in containers with minimal space.
• Companion planting: Naturally repels aphids and whiteflies in mixed gardens (more on basil companions).

Required Conditions for Growing Lemon Basil

Ideal Temperature and Light Conditions

Scientific studies show that lemon basil grows best between 17°C and 29°C (62–84°F). Higher temperatures beyond 29°C can reduce plant height and flowering capacity (source).

• Light: Minimum 6 hours direct light/day. A grow light with PAR value of ≥ 400 μmol/m²/s is ideal (source).

Related: Does Basil Need Full Sun?

Soil Type and Drainage

• pH Range: 6.0–7.5
• Recommended mix: Loamy soil + 20–30% perlite for balanced drainage and moisture retention.

Guide: Basil Soil Requirements

Pot Type, Size & Location

• Depth: ≥ 6 inches
• Material: Terracotta or breathable fabric pots
• Placement: South-facing windowsill or grow tent for indoor setups

Tool Tip: What Size Pot for Indoor Basil?

Step-by-Step: How to Grow Lemon Basil from Seed

Growing lemon basil from seed may seem simple, but optimizing each phase will make the difference between sparse leaves and a thriving, aromatic plant.

Start your lemon basil journey today—grab some seeds and follow these easy steps!

Below is a more in-depth guide that outlines best practices using insights from horticultural studies and home grower experience alike.

Step 1 – Sowing Seeds

• When to start: Begin seeds indoors 6–8 weeks before your last expected frost, or year-round under grow lights.
• Soil setup: Use a sterile, well-draining seed-starting mix. Avoid heavy potting soils at this stage.
• Depth & spacing: Sow seeds 1/4 inch deep and cover lightly. Space about 1 inch apart for germination.
• Containers: Shallow trays or 2-inch plug cells allow for even moisture and warmth.

Starter Tip: How to Germinate Basil Seeds in Paper Towel

Step 2 – Germination Conditions

• Warmth is key: Maintain soil temperatures between 70–80°F (21–27°C). Use a heat mat if needed.
• Humidity boost: Cover with a clear dome or plastic wrap to trap humidity, but ventilate daily to prevent mold.
• Lighting: Provide 12–16 hours of light immediately after sowing — seeds don’t need light to sprout, but seedlings do.

Step 3 – Thinning and Transplanting

• First thinning: Once seedlings reach 1–2 inches tall and have at least one true leaf set, thin to the strongest plant per cell or cluster.
• Transplant timing: Wait until 2–3 sets of true leaves appear and roots begin circling the bottom of the pot.
• Hardening off: If moving outdoors, gradually expose young plants to outdoor conditions over 5–7 days.

Further Reading: How to Grow Basil from Seeds in Soil

Growing from Cuttings: Propagation Guide

Yes, you can grow lemon basil from cuttings just like other varieties!

• Cuttings size: 4–6 inches
• Rooting method: Place in water, optional rooting hormone
• Time to root: 7–10 days
• Transplant: Once roots are 1 inch long

See: How to Grow Basil from Cuttings

Daily and Weekly Care Routine

Watering Schedule

• Young plants: Every 2–3 days
• Mature plants: Every 4–5 days (check topsoil dryness)

Details: How Often to Water Basil?

Fertilization

• Type: Organic NPK (5-10-5)
• Frequency: Every 2–3 weeks

Troubleshooting: Essential Nutrients for Basil

Light Management

• Use a timer for consistent exposure
• Invest in a PAR meter if using LED grow lights

Common Problems: Pests and Diseases

Pests

• Aphids, whiteflies, and spider mites are common.
• Solution: Insecticidal soap or neem oil spray

Guide: Common Basil Pests

Diseases

• Powdery mildew and root rot from overwatering or poor airflow

More: Basil Root Rot

Harvesting Lemon Basil for Maximum Flavor

• When: Before flowering begins, ideally in the morning
• How: Pinch top stems or snip with scissors
• How much: Never harvest more than 30% of the plant at once

Optimize Your Cut: How to Harvest Basil

Storage and Preservation Techniques

Freezing

• Chop leaves and freeze in olive oil or water in ice cube trays
• Retains ~85% of flavor intensity

Drying

• Use a low-heat dehydrator or paper bag method

Compare Methods: How to Oven Dry Basil / How to Preserve Basil

Advanced Tips: Companion Planting & Varietal Selection

• Great companions: Tomatoes, chamomile, peppers
• Avoid planting near: Rue, fennel
• Top cultivars: ‘Mrs. Burns’, ‘Sweet Dani’, Thai Lemon

Explore More: Companion Plants for Basil

FAQs About Lemon Basil

How long does lemon basil live indoors?

Up to 6–9 months if kept in warm, sunny, and well-fed conditions. More: How Long Does Basil Live Indoors?

Can I regrow basil from store-bought?

Yes. Use fresh cuttings and follow propagation tips above. Read more: How to Repot Supermarket Basil

Why is my lemon basil not fragrant?

Usually due to low light intensity or over-fertilization. See: Why Does My Basil Smell Like Licorice?

Final Thoughts and Expert Tips

If I had to give you one takeaway: light and temperature make or break lemon basil. Give it the warmth of a Mediterranean afternoon and light like it’s growing in Sicily, and you’ll be rewarded with citrusy leaves all season.

Need help keeping your basil thriving? I recommend pairing this guide with How to Care for Basil Indoors and Basil 101.

Happy planting!