How to grow basil 

Basil is a hugely popular annual herb and it’s relatively easy to grow. The fragrant leaves add a delicious flavour to many dishes and can also be used for medicinal purposes. It can be grown indoors on a sunny windowsill, or in a sheltered outdoor spot through the warmer summer months. Whether you want to make delicious pesto, top homemade pizzas, or liven up summer salads, here’s everything you need to know about growing basil from seed.

Browse our full range of herb seeds and fill your kitchen garden with ornamental edibles. 

How to choose the best variety of basil 

The particularly fragrant basil 'Siam Queen' has extra large, liquorice-scented leaves
Image: Thai Basil 'Siam Queen' from Thompson & Morgan

There are many different varieties of basil, each with its own unique flavour and growing habit. You’ll commonly find the sweet Italian types in supermarkets, but spicy Thai basil and zesty lemon basil are also very popular. When choosing your seeds, consider the flavours you want to add to your dishes. Alongside traditional favourites, why not experiment with new or unusual varieties that can’t be bought in a shop. 

How to sow basil seeds

Basil 'Purple Ball' produces highly flavoured purple leaves that add something special to tomato-based dishes
Image: Basil 'Purple Ball' from Thompson & Morgan

Basil is an annual herb, so you’ll need to sow fresh seeds each year between February and June. If you sow seeds in succession over several months, you’ll be able to maintain a continuous supply. Here’s how to get your seeds off to a strong start: 

• Fill your pot with a good quality seed compost such as John Innes No 1, and firm it down.
• Moisten the compost and let any excess water drain before you sow your seeds. 
• Sprinkle the seeds across the surface, before covering them lightly with compost or vermiculite.
• Place the pot in a heated propagator, or seal it inside a plastic bag until the seeds have germinated. (This usually takes up to 2 weeks.) 
• Once germinated, remove the plastic bag and grow your seedlings on in cooler conditions. 
• Take care not to overwater the seedlings as they hate wet soil. Keep the compost just moist, and let it virtually dry out between waterings.
• When big enough to handle, transplant your seedlings into individual pots to grow on.

Where to plant basil

As a versatile herb, grow basil in pots or in hanging containers
Image: Basil 'Aristotle' - Kew Collection Seeds from Thompson & Morgan

Best grown in containers, basil needs a sunny spot that’s sheltered from the wind. Once all chance of frost has passed and the plants have been hardened off, find them a bright position outside where they will get a little protection from the harsh midday sun.

Basil grows quickly, and each time the roots appear through the drainage holes you’ll need to move the plants into increasingly bigger pots. If fed and watered regularly and harvested often, they’ll keep going all summer. Just remove any flowers immediately to prevent the plant going to seed.

How to harvest basil 

With a strong, distinctive flavour, you don't need much basil to add to dishes
Image: Organic Basil 'Classico' from Thompson & Morgan

Once your plants reach a height of about 30cm, you can start to harvest the basil regularly. Simply cut individual stems just above a set of leaves. New stems will develop from the leaf nodes to provide you with more tasty basil in a few weeks time. Alternatively, pick single leaves as required. 

Your basil will die off when the temperature starts to drop. You can extend the season slightly by bringing your plants indoors. 

Want to expand your kitchen garden? You'll find more great herb growing advice and plenty of other helpful resources over at our herb hub page.