Gardens

How to grow basil, from seed, indoors and out

One of the most popular culinary herbs, find out how to grow basil successfully to add delicious flavor to many homecooked dishes

how to grow basil, in tray with other herbs
(Image credit: Leigh Clapp)

It's so easy to learn how to grow basil. A wonderfully fragrant herb with a distinctive flavor, there are many varieties of basil that you can use in cooking, and if you know how to grow basil at home you will always have it at hand when you want to rustle up a tasty meal.

Delicious in Italian dishes, salads and pesto, and Thai recipes, it is easy to grow basil from seed. You can either grow basil indoors in a sunny spot, in a pot on the patio where you can enjoy its lovely aroma as you brush past it, or among the vegetables in a vegetable patch.

Growing your own basil allows you to explore different varieties, with flavors and scents that can vary considerably. There are so many different types of basil plants you can grow, from large-leaved Italian, purple, lemon, tiny-leaved Greek basil, to Thai basil with its mild liquorice notes.

If you sow basil seeds successionally from spring you can ensure you have a continuous supply of the delicious leaves to use for cooking into winter.

See: Kitchen garden ideas – easy ways to get started

How to grow basil indoors

how to grow basil

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A true sun lover, basil can be grown indoors as long as you make sure it has about six hours of sunlight every day. In fact, given the right conditions it is one of the easiest herbs to grow indoors.

'Basil likes it hot so will thrive in a greenhouse and is even said to enhance the flavor of tomatoes when grown alongside them as a companion plant,' says Lucy Hutchings of She Grows Veg and author of new book Get Up and Grow.

See: Tomato companion planting

If you don't have a greenhouse or conservatory, choose a sunny windowsill to grow basil plants, such as a south or south-west facing one, but protect the plant from the hot midday sun. 

The plants will need regular watering, although will not like to sit in water or wet compost.

Barbara Segall is editor of the Herb Society magazine and she advises to 'be regular and diligent with water. Don’t let herbs stand in saucers of water, but equally don’t let them go without water in a sunny season.'

How to grow basil from seed

how to grow basil

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One of the most cost effective ways of how to grow basil is to start it off from seed. It is ridiculously easy to do, and you can start to grow basil indoors from seed anytime from March to mid-summer.

  • Start your basil seeds off in small pots or seed trays of moist, peat-free multi-purpose compost.
  • Only sow a few more basil seeds than you need as most will germinate. 'I sow several seeds per pot and thin them out as they grow until there are three to four strong stems,' says Barbara Segall.
  • Cover the seeds with a thin layer of vermiculite. 
  • Water lightly.
  • Use a propagator or cover the pot with a freezer bag secured with an elastic band to increase the temperature.
  • Once the basil seeds have germinated, remove the covering, but keep the compost damp.
  • Thin out basil seedlings so that each one has the space and share of water and nutrients to grow into a healthy plant.
  • When the basil seedlings have developed their first true leaves and are large enough to handle, plant them on into 3.5 inch pots.
  • Pot them on into larger pots as they grow and their roots start coming through the drainage holes at the bottom of the plant pot.

'Water the compost (not the leaves) regularly, in the morning: basil hates having wet feet overnight,' advises food writer Mark Diacono in his new book Herb: A Cook's Companion.

'Cut back to encourage new leaves to form, or enjoy the delicious flowers,' Mark adds.

How to grow basil from cuttings

how to grow basil

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An alternative to growing from seed, if you know how to grow basil from cuttings then you can grow basil plants year round. You can then swap cuttings of different varieties with friends and neighbors, and it is a great way to make garden ready plants from supermarket herb plants or garden centers. 

'It is really easy to make a seemingly endless supply of basil plants from just one,' says Lucy Hutchings.

'Take cuttings of around 6-8 inches long, remove the lower leaves and place in water. Within around a week you will see new roots growing from the submerged stem.

'Once there are a few decent looking roots, pot up your cutting and enjoy your new basil baby,' adds Lucy.

  • If you use tap water, leave it for about 24 hours before adding the basil cutting.
  • Place on a sunny windowsill, although out of direct sunlight.
  • Change the water every couple of days to prevent bacteria from growing.
  • When the roots of the basil cuttings are an inch or two long, remove the cuttings from the water and pot them up into a container filled with pre-moistened potting mix. 

Keep the planted basil cuttings in a humid environment – place them in a propagator, or cover with a clear freezer bag. Once they have started to develop new growth, pot them on into larger pots.

Growing basil from cuttings cuts growing time by about half, so you will soon have some delicious leaves to harvest.

See: Small vegetable garden ideas – from layout designs to the best crops to grow

How to grow basil outdoors

how to grow basil - picking leaves

(Image credit: Leigh Clapp)

Even if you want to learn how to grow basil outdoors, you still need to start the seeds off in pots inside from spring, either in a greenhouse or on a warm windowsill. 

Sow the seeds in small pots of moist peat-free multi-purpose compost, cover with a thin layer of vermiculite, and place in a propagator or cover the pot with a freezer bag. 

Once the seeds have germinated, remove the covering. When they have developed their first true leaves and are big enough to handle, plant into individual 3.5 inch pots.

When to plant basil outdoors

Put your young basil plants that you have started off indoors, outside in early summer, after the last frost.

'Always wait for the air and soil to warm before moving basil into the garden,' advises author and gardening expert Melinda Myers.

'Cold air and soil can stunt or damage the plants and increase the risk of downy mildew. You may even see blackened leaves and other damage,' Melinda adds.

For how to grow basil outdoors, acclimatize the basil plants to the conditions outdoors for about two weeks before planting them out. Do this by standing them outside in a sheltered, lightly shaded spot during the day, and bring them back in at night time. 

'This plant is really not a fan of the cold, so wait until night time temperatures are up to around roughly 50ºF before you plant out basil it into its final position,' advises Lucy Hutchings.

Where to grow basil outdoors

how to grow basil in the garden

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When you come to plant the basil plants in your garden, choose a sunny, sheltered spot with well-drained soil.

Celebrity gardener Monty Don advises that how to grow basil is it needs generous space to grow well. He recommends a space of 9 inches between the plants when they are 4 inches tall, so that the basil will grow vigorously.

How to grow basil in a pot

how to grow basil in pots outside

(Image credit: Leigh Clapp)

Basil also grows well in containers outdoors, and the advantage of this is that you can move the plant around to give it pride of place in the sunniest, sheltered spot. 

Experts at Dobbies recommend adding a layer of grit to the surface of the compost in each pot to keep weeds at bay and stop rain splash marking your herbs.

Basil will grow fast in pots, so you can expect to have to pot up the plants a few times during the growing season.

In fall, when temperatures start to dip, bring a few plants back indoors to provide a fresh supply of leaves in winter.

Caring for basil plants

how to grow basil harvesting the leaves

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  • Water basil plants sparingly as they do not like to sit in wet compost.
  • Ideally water before midday, to avoid basil plants developing mould if they are damp at nighttime, and avoid splashing the leaves.
  • Feed basil plants with liquid fertiliser every week to keep your herbs at their best.
  • Pinch out the flowering tips to delay flowering and encourage bushiness.

'How to grow basil in order to achieve nice big bushy plants, is to cut off the top ¾  inch of immature plants when they get to about 6 inches tall. This will stimulate them to branch out and become bushier plants rather than tall and thin,' advises Lucy Hutchings. 

'You can keep doing this as your plant sends out new stems and don’t forget to add what you snip off into your next salad,' Lucy adds.

Harvesting basil

Pick the leaves from the top of the basil plant regularly to use fresh in cooking, and to encourage new growth and a bushier shape. You can be quite ruthless when harvesting basil. 

Harvest the leaves  of the basil plant individually rather than cutting the plant with scissors, as this will enable new leaves to grow.

'Regular harvesting of basil will increase productivity and ensure the best flavor. Remove flower buds as soon as they appear to maintain foliage flavor. But don’t worry if a few blossoms appear, these are also edible and make a lovely addition to salads,' says Melinda Myers. 

See: How to grow garlic – a step by step guide to growing from cloves

Mark Diacono advises not to refrigerate harvested basil leaves as 'this accelerates their decline.'

When cooking with basil 'its flavor floats away in the steam of any heat, so it’s almost always best added on serving. The exception is if using gently warmed in milk, cream or oil to extract the flavor,' says Mark. 

So, armed with all the tips you need on how to grow basil, you can add wonderful depth and flavor to a multitude of dishes with this versatile herb.