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How to Grow Basil Indoors

Growing basil indoors is perfectly possible for most home growers, especially for those already growing vegetables indoors. This herb ideally prefers a spot outside but it can also thrive in an indoor garden when provided with what it needs.

Grow basil indoor

To grow basil indoors, you first need to consider:

  • Where basil can be grown indoors. 
  • Which basil to grow. 
  • How to grow basil from seed. 
  • Care requirements for basil growing indoors. 
  • And how to harvest basil from an indoor garden. 

Where to Grow Basil Indoors

The most important thing when growing any basil indoors is to understand that these are light-loving plants that require at least 6 hours of sunlight per day or grow lights that can provide the equivalent. 

When choosing where to grow basil, environmental requirements are key. Basil needs:

  • A sunny spot, with at least 6 hours of full sun each day (or full-time grow lights).
  • Temperatures above 21 degrees Celsius through the summer and no lower than 10 degrees Celsius throughout the winter months. 

When growing in a pot indoors, basil needs:

  • Free-draining soil that won’t get waterlogged, where excess water can drain away freely. 
  • A fertile soil/ growing medium with depth to accommodate the roots. 
  • Ideally, a pH of 6-7. (Though the plants can tolerate a pH between 5 and 8.)

Bear in mind, however, that basil can also be grown with its roots in water in a hydroponic or aquaponic system. And these systems can potentially also be implemented inside a home. 

Choosing a container for basil, you will have a lot of options. Choosing reclaimed container options is an eco-friendly and sustainable choice. 

For example, you might grow basil in old yogurt pots with holes for drainage in the base. You might make a planter or even a vertical garden with planting pockets from a range of reclaimed materials. 

Remember also that basil might be grown on its own, but it might also be grown in containers alongside other fruits, vegetables, or herbs that you are growing in your home. Basil makes an excellent companion plant. 

In particular, basil is an excellent companion for tomatoes, and also for peppers and other members of the same plant family. The aromatic herb helps to repel certain pests and some even say that it can improve the flavor of tomatoes and certain other crops growing close by. 

Of course, it can be handy to grow tomatoes and basil together because they are not only good companions in the garden but also in a range of recipes and on the plate. 

Types of Basil for Indoors Growing

As well as deciding where you will grow basil and the method you will use, you also need to think about which type of basil to grow. There are many different species and cultivars that you might consider.

Many of the basil varieties that are most commonly grown are cultivars of Ocimum basilicum – common basil. 

There are varieties of common basil that have larger leaves or smaller ones, red or purple-hued basil varieties, stronger and more delicate-flavored basils, and ones with different flavors, such as lemon basil, for example…

There are also other Ocimum species offering other basils to grow. Holy basil, or tulsi, Thai basil, cinnamon basil, lime basil, and clove basil are just a few examples…

Different basils do vary somewhat in their environmental requirements and the care that they require. But all can be grown indoors. 

Sowing Basil Seed Indoors

For growing outdoors, basil seeds are sown around 4-6 weeks before the last frost date in a temperate climate. Indoors, you have more leeway when it comes to sowing time. But it is still a good idea to sow at around the same time. 

Plant the seeds into seed trays or some small pots, around 6mm deep. Use a propagator or ensure that temperatures remain around 21 degrees C. for the best germination rates. The seeds should germinate within a week or two. 

Seedlings sown in a seed tray can be potted up into individual containers once they develop a few sets of true leaves. 

The containers should be filled with a suitable, peat-free growing medium (unless, of course, you have opted for a water-based growing system). A mix of 1/3 homemade compost, 1/3 loam or loamy soil, and 1/3 leaf mold (which you can also make at home) works well. 

Caring for Basil Indoors

When watering basil growing indoors, try to water consistently, and early in the day where possible. Water the growing medium below the plants rather than wetting the foliage. 

Watering in this way helps to ensure that water gets to the roots where it is needed, and reduces the chances of mildew or other fungal issues taking hold. 

Basil growing in pots indoors will appreciate being fed with a nitrogen-rich organic liquid plant feed every couple of weeks through the growing season. 

Harvesting Indoors Basil

Harvesting is also part of the care for basil plants. Harvesting the top leaves little and often as needed will encourage the plants to branch out and become bushier, putting on fresh new growth. You can start harvesting basil as soon as the plants reach around 15-20 cm tall. 

Handle the leaves carefully when harvesting as they bruise easily. Harvest them early in the morning when their essential oil production should be high and the plants should be less stressed for the best flavor. 

Nip off flowering shoots when these form so that the harvesting period can continue. Basil will not taste as good after the plants’ flower. 

Most basils are grown as annuals indoors in a temperate climate, and seeds are sown fresh each year. They can survive over multiple years but won’t thrive, so growing replacement plants each year is generally the best idea.