How to grow Thai basil in 17 easy steps

Thai basil is a must in Thai cooking. A cousin of the more common sweet basil, this aromatic herb can be used in many dishes. It’s also a very easy plant to grow, and can be grown indoors or outdoors.

In this article we’ll show you the steps you take to grow sweet Thai basil and how to succeed in cultivating your own basil plants!

Basils variety, flavor and color

There are many basil varieties to try, in exciting flavors and colors. The most popular varieties are Thai basil and sweet basil. The two plants look similar, but they both have a different flavor profile, which means you can experiment with matching them to your cooking needs. 

Beautiful colors of Thai basil starting to show
The characteristic colors of Thai basil emerging.

You can also mix other basil varieties in your gardening planters. For example lemon basil is a popular variation that produces a strong citrusy flavor. Whilst cinnamon basil has a spicy, cinnamon flavor and works well in sweet desserts such as chocolate mousse and apple crumble.

Some varieties of basil also come in colors, like purple or bronze which make for beautiful cut flowers and will add something different to salads at the dinner table.

However sweet Thai basil is amongst the most popular to grow. It has a scent similar to licorice and an intense flavor, making it my favorite.

Use it in dishes like tom yum soup and curry because it has a spicy pepper taste that brings balance to these styles. I also use its versatility in salads, smoothies, Thai stews, pestos and dressings.

Basil is an annual meaning that you need to sew each year for a new plant. It is best grown in a container rather than sewn freely amongst other plants in the garden.

Propagate from seed in early Spring and follow our how-to tutorial below!

You will soon have a fantastic sweet Thai basil plant that will grow to around 30-40cm tall in your kitchen garden!

17 Easy steps to growing your own Thai basil

True leaves forming on Thai basil seedling
True leaves on Thai basil seedlings
  1. Start with buying good quality seeds from your local garden center and a sack of potting soil. 
  2. Choose the pots or containers you want to use. If you use pots that you have at home from previous plantings, wash them out thoroughly to ensure you get rid of any pests or bugs before you start your new planting.
  3. Make sure that the pot or container has drainage holes and adequate air circulation.
  4. Fill your pots with planting soil. Water the soil, letting any excess water drain out the drainage holes.
  5. Sprinkle the seeds sparingly on the surface of the soil. Place a thin layer of potting mix on top and seal it in by pressing firmly with your fingers. Thai basil seeds germinate in 7-10 days.
  6. Choose a location such as a sunny window sill that gets plenty of sunlight for at least six hours each day, and is about 20-25 degrees warm. This is important so the plant will grow fast enough to produce optimal yields and flavors.
  7. Give the seeds their first watering and from now on ensure the soil is slightly moist at all times. Water them regularly and gently letting excess water drain at all times through the holes in the base of your pots.
  8. Cover your pots or planters with plastic until you see that the seeds have germinated and tiny green shoots start to show.
  9. When the seedlings are big enough to handle, you will need to transplant them into larger pots with 3 to 4 seedlings in each.

    Remember to always use nutrient-rich moist soil for best results. Separating the seedlings like this gives each plenty of room to spread its roots as it grows, resulting in a strong and fruitful plant.
  10. At this point it is important to remember not to place the pots in direct hot sun all day long as there is a risk of scorching the plants.
  11. As the plants continue to grow, make sure they get plenty of air circulation. Basil is sensitive to heat and will start wilting if temperatures rise above 28 degrees Celsius (82 degrees Fahrenheit).
  12. You should also keep them well watered but water in the morning to let the plant soak up the water during the day. Basil does not like its root sitting in water all day and night and therefore morning watering is a good idea.
  13. If you use a good quality potting soil when you sow your Thai basil seeds, you will not need to use any fertilizer.
  14. As the plants grow, pinch off any flowers that may bloom to promote leaf growth.
  15. Basil thrives really well if you are able to keep your pots in an area with shelter, such as a greenhouse or a glassed-in balcony. This will protect the leaves from strong winds and they will become larger and sweeter.
  16. Basil is also a favorite of aphids, slugs and snails. So keep your containers or pots raised if at all possible and check regularly that these creatures are not attacking your plants.
  17. If you want to keep your pots outside, keep an eye on the weather. If the temperature drops to under 15 degrees c move your basil pots indoors. They do not like chilly weather.

Grow Thai basil plants from cuttings

We use a lot of Thai basil and I like to have new plants on the go throughout the year.

Growing Thai basil plants from cuttings
New white roots start to form

My favorite method to start new plants is by taking cuttings from one of my healthy seed grown plants.

I pinch the stem just above the third pair of leaves starting my count below the top crown.

Ideally I like cuttings to be 7-10 centimeters (3-4 inches) long. But shorter cuttings can also work.

Remove all leaves below the crown and place the stem in a glass with room temperature water.

Ideally we give the stem fresh new water every day.

After 2-4 weeks weeks we will see new white roots forming on the stems.

When we are happy we the level of root development we simply plant the stem in a pot with soil. And now we have a new Thai basil plant to care for and harvest.

Harvesting your fresh basil

When your Thai basil is sufficiently large, it will be time to harvest the leaves for cooking. Harvest your basil leaves when the leaves are large, plump and shiny. At this point the plant should be around 15 to 20 cm tall.

Depending upon what you are using your Thai basil for and how much you need, either just pick the leaves you need or you can cut entire stems. Cut the stem directly above where you see a pair of leaves, at about a third of the plant’s height. Then let that stem grow for another few weeks.

To keep your cut basil from becoming wilted, put it in water with just-boiled cool tap water and then cover or store it in the refrigerator until you need to use it.

Drying basil leaves

You can also harvest and then dry your Thai basil to use at a later date. Place the leaves in an airtight container lined with paper towels, put it somewhere dark and cool like a pantry or cupboard and let them lay there until they are ready to be used again. The dried Thai Basil can be used for flavouring in cooking, or it can be used as an ingredient to make your own basil-infused oils.

Freezing basil leaves

This is an ideal way to make your home-grown Thai basil leaves last even longer. Wash and pat dry as many leaves as you want to freeze. Place them in a single layer on a plate or baking tray, put that in the freezer until they are frozen solid. Transfer the basil from those trays into zippered bags and store it in your freezer for up to six months.

Summary and conclusion

Thai basil is an excellent plant for the beginner gardener as it does not require a lot of attention.

Thai basil is easy to care for and with its many uses and benefits we definitely recommend that you make room for it in your herb garden!

Thai basil from seed
Grow Thai basil from seed for exotic flavors all year round

Meet the author: Mattias is an experienced gardener spending most of his free time on his knees among herbs, plants and garden vegetables. For the past two years he has been sharing gardening projects and how-to tutorials on the NordicLavender website and YouTube channel.