An expert's guide on how to grow basil

how to grow basil
How to grow basilMelissa Ross - Getty Images

I love a plant that gives you lots of reasons to grow it and basil offers up plenty. Not only do you get a vibrant plant for the window box and a delicious herb for cooking, basil also yields flowers for pollinators, herbal properties for wellbeing, protection for your tomato plants and even flowers for the vase.

What are the different varieties of Basil?

Sweet basil (Ocimum basilicum) is generally the one you’ll find wrapped in plastic in a supermarket, and it’s what we know as the classic basil used in Italian dishes from punchy pestos to fresh caprese salads. Varieties include ‘Genovese’ and ‘Napoletano’, which are easy to find as packets of seed, but the beauty of growing your own is that you can experiment with different varieties.

I’m often drawn to the deep and sultry shades of purple basil (O. basilicum var. purpurascens), which bring something unique to both pots and plates. I grow it among my ornamentals as it looks so striking in a container display. It brings something to the kitchen table, too. ‘Red Rubin’ has a deep, robust flavour that makes for a pungent pesto, while the flouncy, crimped leaves of ‘Purple Ruffles’ give a relatively mild basil hit to a mixed-leaf salad.

Greek basil (O. minimum), or bush basil as it’s also known, is equally pretty. It has little oval leaves and can be pruned into cute rounded forms – ideal for small pots placed on alfresco tables, particularly as it’s also an effective bug repellent.

For drinks, lemon basil (O. × citriodorum) brings with it a spike of citrus – this is one I love in a glass of sparkling water or gin and tonic, or as a tea steeped in hot water. Just snip off a few young, fresh leaves and pop into your glass or mug. Again, there are several varieties, with ‘Lemonade’ a good go-to.

The world of basil doesn’t end there: look out for cinnamon basil, which brings with it a warm spice that’s ideal for marinades; basil ‘Blue Spice’, that has a really interesting vanilla-meets-licorice flavour; and the popular aromatic for curries, Thai basil.

how to grow basil
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How do you grow basil from seed?

It’s worth sowing a few batches a few weeks apart so that you can achieve a generous basil harvest all summer long. You can sow indoors at any time of year, but you need plenty of warmth and light, so spring is the ideal time to get going.

Fill a cellular tray with peat-free compost. Water the compost very lightly. Press a couple seeds into each cell, no deeper than 5mm. Keep the tray indoors somewhere warm and bright but out of direct sunlight.

Germination should happen within two weeks. Basil doesn’t like to sit soggy, so don’t get heavy-handed with the watering. After seeing the first shoots, wait until you see a few true leaves (ones that look like the final basil plant), before carefully potting each seedling on into its own small pot. It’s best to push out the seedling with its soil from each cell, rather than tugging at it, as it’s very easy to damage basil’s roots. You can keep potting on the basil as it gets bigger and keep your plant indoors, or you can prepare it for life outside…

How do you grow basil successfully?

Within a few weeks, usually about 6, the basil seedlings will be ready to plant outside. Make sure all risk of frost has passed and, if you like, put the plants out during the day to help acclimatise them. You can transplant the baby basil plants to a larger pot, into a window box with other plants, or into the ground. Make sure the compost or soil is light and free-draining and choose a sunny spot for your herbs.

Basil is a tender annual and needs protection from frost and even cold nights, so don’t put your plants outdoors too soon in the year and bring them in before autumn’s cold. Slugs love basil (why wouldn’t they!), and the herb is also susceptible to a mould called botrytis. To reduce the risk of both, water your plants in the morning and avoid splashing the leaves with water.

how to grow basil
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How do you harvest and store basil?

You can pluck the odd leaf here and there for garnishes and cocktails, but to harvest a bunch, it’s best to take a pair of secateurs to the plant, making a cut low down the stem, but just above a pair of leaves. This allows it to keep growing strong and healthy.

To store, treat like a cut flower: trim the stems before placing in a jar of cold water. Alternatively, wash, dry and wrap in kitchen towel before placing in a plastic box or bag and storing in the fridge. Either way, basil should stay fresh for about a week.

How do you use basil?

As well as the kitchen uses, aromatic herbs in general are fantastic companion plants, and basil is no exception. Plant it beneath your tomatoes (or put a few pots in the greenhouse) and it'll help stave off an aphid infestation. Note that the aphids will head for the basil! So it’s something of a sacrifice, but a worthwhile trick to have up your sleeve. A pot of the herb is equally effective in the kitchen: pop it on the windowsill to deter flies and other pests, and you can still enjoy the leaves yourself.

It can also be used for wellbeing. One simple way of harnessing some of that power is to make a basil massage oil – infuse a few handfuls of the fresh herb in a sealed jar of scentless coconut oil for a few weeks to capture the essential oils.

Some varieties of basil grown outside can reach two or even three feet tall. And if left to flower, they look glorious – spikes of pink, purple or white flowers are brilliant at attracting pollinators, and a few stems brought into the house make great cut flowers.

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