Growing Thai Basil Indoors

Thai basil is a popular culinary herb that is essential for making authentic Thai cuisine. With its distinct licorice-anise flavor and spicy kick, Thai basil packs a flavorful punch and livens up stir fries, curries, soups, and more. While this tropical basil variety thrives outdoors in warm climates, it can also be grown successfully indoors with proper care.

Growing Thai basil at home allows you to enjoy fresh basil year-round. Having a supply of this aromatic herb on hand means you can add its unique flavor to dishes anytime. From seed starting to harvesting, this article covers everything you need to know about cultivating Thai basil indoors.

Selecting the Right Thai Basil Variety

There are a few different varieties of Thai basil to choose from. The most common type grown is called ‘Siam Queen’, which has a bold licorice and clove taste. Other varieties like ‘Horapha’ and ‘Jay Bai’ offer slightly different flavors.

When selecting which Thai basil to grow, consider:

  • Flavor profile – Siam Queen has the strongest anise-licorice notes while Horapha is more cinnamon-like.
  • Plant size – Horapha grows larger than Siam Queen. Go for Siam Queen if growing in a limited space.
  • Pest and disease resistance – Jay Bai shows good resistance to Fusarium wilt.
  • Culinary use – All varieties work well, but Siam Queen is the most popular for Thai cooking.

No matter which you choose, look for Thai basil seeds or starter plants from reputable sources. This helps ensure you get the exact variety you want.

Starting Thai Basil from Seed

One of the most rewarding ways to get Thai basil plants is to grow them yourself from seed. Starting the seeds indoors allows you to get a head start on the growing season. Here are some tips for success:

When to Start Seeds

Start Thai basil seeds indoors 6-8 weeks before the last expected frost. This gives the seedlings time to develop into sturdy transplants before moving them outside.

If growing indoors year-round, you can sow seeds anytime. Just make sure to account for the 10-14 day germination period when planning your harvest timeline.

Seed Starting Mix

Use a sterile, soilless seed starting mix to prevent damping off disease. The mix should be fine textured yet well-draining. Lightly moisten it before planting.


Sow seeds in cell packs, flats, pots or trays. This makes it easy to thin and transplant seedlings later on. Make sure containers have drainage holes at bottom.

Planting Depth

Sow Thai basil seeds just 1⁄4 inch deep in the seed starting mix. Tiny basil seeds need light to germinate. Cover lightly with a thin layer of vermiculite.


Keep seeds consistently warm, around 70-80°F. Basil seeds won’t germinate well in cool soil. Consider using a heat mat.


Place under grow lights or in a sunny window after sowing. Strong light prevents leggy seedlings.


Water lightly from below to keep soil moist but not soggy. Basil seeds will rot in overly wet conditions.

Days to Germinate

Thai basil seeds take 10-14 days to sprout. Be patient! Once germinated, they’ll grow quickly.

With proper care, starting Thai basil from seed is easy and rewarding. In no time, you’ll have young seedlings ready to pot up or transplant into the garden.

Growing from Nursery Transplants

For instant gratification, purchase Thai basil transplants from a local nursery or garden center. Look for young plants around 4-6 inches tall that appear healthy and vigorous. Avoid spindly, root-bound, or flowering plants.

When selecting transplants, check for:

  • Dark green, glossy leaves
  • Bushy, compact shape
  • No sign of pests, diseases, or damage

Gently remove transplants from their pots, being careful not to disturb the roots. If roots are densely circled around the root ball, gently loosen them before planting.

Transplant intocontainers filled with well-draining potting mix. Make sure the container has drainage holes. Set the transplant at the same level it was growing in the nursery pot.

Water well after transplanting and provide bright light. Newly planted basil may show some wilting or stress, but should perk up within a few days as it adjusts.

Nursery transplants provide an instant harvest. With good care, they’ll continue growing vigorously indoors.

Propagating from Cuttings

An easy way to multiply Thai basil plants is taking cuttings from an established plant. Here’s how:

Select Tip Cuttings

Take 3-4 inch long stem tip cuttings that don’t have flowers. Make cuts just below leaf nodes using sterilized shears.

Remove Lower Leaves

Strip off the lowest leaves from cuttings so you have bare stem at the bottom. This helps prevent rotting.

Dip in Rooting Hormone

Dip the bare end of cuttings in rooting hormone powder to stimulate root growth. Tap off excess powder.

Insert in Media

Stick cuttings in sterile seed starting mix, perlite, vermiculite or water. Rooting hormone is key for water propagation.

Provide Warmth and Humidity

Place cuttings in a warm spot (70-80°F) with high humidity. Consider covering with plastic to maintain moisture.

Wait for Roots

Check for root development in 2-3 weeks. Gently tug cuttings to feel resistance from new root growth.


Once cuttings have rooted, pot them up in regular potting mix to establish as new basil plants. Provide ample sun.

Taking basil stem cuttings is an easy propagation method. With warmth, humidity and rooting hormone, cuttings readily form roots for new potted plants.

Choosing the Right Growing Container

To grow Thai basil indoors successfully, start with an appropriate container. Here’s what to look for:

Drainage Holes

Make sure containers have adequate drainage holes at the bottom to prevent soggy soil. Elevate pots to improve drainage.


Select containers at least 6 inches deep so basil roots have room to develop. Shallow pots restrict growth.


For mature plants, use at least a 6-8 inch diameter pot. This provides enough space for bushy basil to grow.


Plastic, ceramic, fabric or metal pots all work well. Make sure containers are clean before use.

Avoid decorative pots without drainage holes. While attractive, these will lead to wet soil and root rot in basil plants.

Invest in good quality containers with drainage and enough depth for developing a vigorous indoor basil crop. This gives your plants the best chance to thrive.

Providing Proper Lighting

One of the keys to growing thriving Thai basil indoors is providing very bright light. Basil is light-loving plant that grows best with 8-10 hours of full sun daily. With indoor growing, artificial lighting is often necessary.

Sunny Window

A south-facing window with direct sun exposure allows basil to photosynthesize well. Rotate plants to ensure even growth.

Grow Lights

Full spectrum LED or fluorescent grow lights work beautifully for indoor basil. Position lights 6-8 inches above plants.

Light Duration

Whether using sun or grow lights, aim for at least 8-10 hours of bright light exposure for productive plants.

Monitor Growth

Leggy, weak growth is a sign plants want more light. Increase duration or move lights closer as needed.

Basil stretched for light becomes woody and bitter tasting. Invest in quality lighting and properly position plants to encourage bushy, compact growth indoors.

Controlling Temperatures

Thai basil grows best in warm temperatures between 70-85°F. Cooler temps below 50°F can damage plants or cause poor growth.

Warm Day Temps

Maintain daytime temperatures of 75-80°F for active growth. Move plants to warmer rooms as needed.

Cool Nights

Night temps around 65-70°F are preferred. A 10-15 degree drop at night is fine. Just avoid chilly nights.

Supplemental Heat

Use a portable heater, heat mat or grow lights to maintain warm temps if your home is cool.

Air Circulation

Good air flow prevents fungal diseases. Use fans to circulate air around indoor basil.

Monitor indoor growing space temperatures and make adjustments as needed. With the proper warm conditions, your Thai basil will flourish.

Providing Adequate Water

Basil plants prefer evenly moist but not soggy soil. Take care not to over or underwater container grown plants.

Water Requirements

Water Thai basil when the top 1-2 inches of soil become dry

Soil Meter

Use your finger or a moisture meter to check soil. Probe near the plant’s base to get an accurate reading.

Water Until It Drains

When watering, add enough so it runs freely from the container’s bottom drainage holes.

Self-Watering Pots

Consider using self-watering containers to provide a constant moisture supply.

Drooping Leaves

If leaves droop, it’s a sign plants need water. Take action to revive thirsty basil.

Yellow Leaves

Overwatering causes yellow, dropping leaves. Allow soil to dry out somewhat before watering again.

Air Circulation

Improve air flow around plants to reduce humidity and risk of diseases.

Aim to mimic outdoor growing conditions with thorough watering followed by periods of drying. Proper moisture management prevents many common basil issues.

Using the Right Potting Mix

To grow thriving basil indoors, start with a quality potting mix:


Choose a mix containing perlite, vermiculite or coconut coir to prevent compaction and improve drainage.


A general purpose mix with a balanced nutrient ratio encourages vigorous growth.

Nutrient Charge

Avoid “hot” mixes which can burn basil roots. Mild fertilization is sufficient.

Peat Content

Some gardeners avoid peat-based mixes, but these work fine for basil as long as you don’t overwater.

Soilless Mixes

Sterile potting mixes prevent diseases and help plants grow more vigorously indoors.

With a well-aerated, nourishing potting mix, your Thai basil plants get off to a great start. Re-pot into fresh mix every spring to replenish nutrients.

Fertilizing for Optimum Growth

While Thai basil plants don’t require heavy feeding, light fertilization keeps plants productive indoors.

Organic Options

Use worm castings, compost tea, fish emulsion or organic liquid feeds every 2-3 weeks.

Synthetic Fertilizers

Apply a balanced soluble fertilizer at 1⁄2 strength every 2-4 weeks during active growth.

Slow Release

Top-dress containers with a mild slow-release fertilizer pellet every 2-3 months. Scratch into soil.

Yellowing Leaves

This indicates possible nitrogen deficiency. Increase organic or synthetic fertilizer to deepen green leaves.

Excess Fertilizer

Burned leaf tips or stunted growth means you’ve over-fertilized. Flush soil and resume at a lower dose.

With light, regular feeding, your indoor Thai basil will stay lush and productive for months on end.

Common Pests to Watch For

Growing indoors minimizes pest problems, but be on the watch for these common invaders:

Fungus Gnats

These tiny flying insects indicate overwatering. Allow soil to dry out to discourage them. Use yellow sticky traps.


Check for clusters of small, soft-bodied insects on new growth. Wipe off with insecticidal soap or neem oil.

Spider Mites

Webbing and stippling damage on leaves comes from tiny spider mites. Spray forcefully with horticultural oil.


Clouds of tiny white insects fluttering around plants indicates whiteflies. Hang up yellow sticky traps to catch adults.

Act swiftly if pests appear and treat organically to preserve your harvest. Prevent infestations by promoting vigorous plant growth.

Harvesting and Preserving Your Crop

One of the joys of growing Thai basil is harvesting it fresh anytime for cooking. Here are some tips:

Harvest Time

Begin harvesting Thai basil once plants are about 6 inches tall. Snip sprigs as needed.

Harvest Method

Cut stems just above leaf nodes using clean bypass pruners or kitchen shears.


Pinching off stem tips encourages bushy, compact growth. Keep plants pruned back.


Store freshly cut basil in an airtight container in the fridge for up to one week.


Air dry small basil bundles out of sunlight before storing in airtight jars.


Freeze chopped basil in ice cube trays covered with water or olive oil for longer storage.

Enjoy your homegrown Thai basil fresh, dried, or frozen. Proper harvesting and storage lets you savor the flavor year-round.


With the right variety, conditions, and care, it is certainly possible to grow flavorful Thai basil indoors no matter where you live. Following this guide will help you be successful cultivating this exotic basil in your own home. The reward of having fresh Thai basil available anytime is well worth the effort.

From starting seeds under lights to troubleshooting pests, this article covered the key things you need to know. Tailor the techniques to your own indoor growing environment. In as little as 2 months, you can have potted Thai basil ready to harvest.

So go ahead and get growing! Add a pot of homegrown Thai basil to your kitchen herb collection. Let the intoxicating anise-licorice fragrance and unique flavor enhance your cooking all year long.