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All you need to know

Basil

Searching for a herb that's as attractive as it is flavoursome? Look no further than the myriad leaf textures and aromas of basil

Pungently aromatic and bursting with vibrant flavours – basil is the first herb that comes to mind as a catch-all addition to so many dishes.

A native of tropical regions of Asia and believed to have originated from India, basil has tracked its way across the globe to become a firm favourite in many national dishes. In the Mediterranean it now grows wild and forms the basis to pasta sauces and succulent salads. Indian and Thai recipes use the herb in many dishes to create a depth of taste that’s unrivalled. Meanwhile British gardeners have learnt that basil is one of the most accommodating of all the herbs, quick to grow and producing masses of aroma-packed leaves to satisfy our love of international cuisine.

Anyone can grow basil, even those without a garden. All that’s required is a warm, sheltered and sunny position where the plants can settle back and imagine they are in their native lands. A range of leaf colours, textures and shapes make basil an intensely pretty herb that looks equally at home with the bedding plants as it does in its own terracotta patio pot.

The commonest form of basil that’s widely available is the versatile sweet basil but there are many other forms that will help expand your culinary horizons. Purple basil, for example, has a warmer flavour that’s the perfect complement to rice dishes, while lemon basil is delicious with fish. Thai basil has spicy undertones, and Mexican cinnamon basil a distinctive taste of that spice. All these flavours are due to subtle differences in the essential oils that go to make this a fascinating herb worthy of further investigation.

Being a tender herb, basil cannot tolerate frost, so most plants are started off in pots inside before being planted out after the final frosts of spring. This gives plenty of time to prepare the ground for these sun-lovers. The soil should be free-draining but full of nutrients. This is easy enough to achieve by ensuring that plenty of compost is dug in during the months before planting time. Sticky clay soils may need further improvement by digging a little gravel into the site just before planting. This will open up claggy plots and facilitate their drainage.

In most parts of the country a sunny and sheltered position should suffice to yield a generous crop of leaves over the summer months. In colder or exposed regions of Britain some further protection may be necessary however. If summer is late to arrive and autumn early, your basil will need some extra warmth courtesy of a bell cloche or similar to create a mild microclimate. Basil may also be grown in a greenhouse, conservatory or on a windowsill in such instances.

Start your basil off any time from early April to the end of June in 7cm pots of multipurpose compost. Fill the container to within 1cm of the rim and then water the pots to settle. The compost will sink a little, which is perfectly normal. Now sow the tiny seeds as thinly as possible; about ten seeds per pot is ideal as almost all of them will germinate.

After sowing use a fine mesh (a flour sieve is good) to sift a thin layer of compost over the seeds until they are concealed. Place a covering of clear plastic, secured in place with an elastic band over the pots (alternatively use cling film). This creates a warm and humid microclimate to encourage quick germination.

Keep the pots on a warm indoor windowsill or in a greenhouse propagator, maintaining a temperature of at least 15°C as the seedlings appear. As soon as they do, ease back the covers to let in a little fresh air and after a few more days remove it entirely. Water the seedlings as necessary, standing pots in a shallow tray of water and allowing the liquid to soak up from the base to avoid disturbing the delicate seedlings. Outdoor sowings can commence from the end of May when the soil temperature should be warm enough. Sow seeds into prepared ground in rows 30cm apart and at a depth of 0.5cm. Fleece or cloches are recommended to raise the temperature a few degrees further. Continue sowing until the end of June.

Indoor-sown basil seedlings will need to be pricked out into their own pots as soon as they reach about 3cm tall. To do this, carefully tap out the seedlings and compost from the nursery pot onto a flat surface. Now use a dibber or pencil gently to tease apart the individual seedlings.

Fill new 7cm pots with multipurpose compost and drill down a hole into each ready to receive the roots of the seedling. Always hold the seedlings by their leaves to prevent damaging the delicate stem and lower the roots down into the hole, coaxing them downwards with the tip of your dibber or pencil. Firm back the soil around the roots and water the pots from their bases until you can see moisture at the compost surface. Move the newly potted seedlings to a warm spot where they can recover.

The seedlings will grow on into young plants and will be ready to go outside as soon as the soil has warmed and frosts are no more. Accustom them to the great outdoors by moving them out to a cooler position, such as a cold frame, for at least a week beforehand, removing the glass lights during the day. To plant out, tap out the plants from their pots and dig a suitable-sized planting hole with a trowel. Firm them back in and water well. Space plants at least 22cm apart and up to 30cm to give each plenty of room to expand, depending on the variety.

Direct-sown seedlings may be thinned to their final spacing in stages. Use the wastage as an early salad crop or transplant them to other parts of the garden – perhaps near fruiting vegetables such as tomatoes and peppers to deter pests. Basil may also be planted out into larger containers of John Innes No. 2 compost. This is a good technique in colder areas, enabling the basil to be moved indoors when cold or particularly windy weather threatens.

Plants will need watering in any dry weather, especially after planting. Water at the base of plants to avoid soaking the leaves and stems, which can encourage fungal diseases. You can lock in soil moisture by spreading a layer of mulch around plants. Container-grown basil will need watering more often, as much as three times a week. Apply a liquid fertilizer, such as diluted seaweed or comfrey feed, to these container plants twice a month to encourage even growth.

Left to its own devices basil will quickly stretch upwards and run straight to flower. While this is undoubtedly a beautiful sight it means fewer leaves for you to pick. Promote leaf production right from the start by regularly pinching out the growing tips of stems. This is easily done by nipping out the top two leaves and growing point of each stem between your finger and thumb. The result is the stimulation of more shoots further down to bush out the plant. When flowers do show up, pinch them out early on to keep plants filled out and to encourage those aromatic leaves for as long as possible.

Pick little and often to get the most from your plants. It is better to take a couple of leaves from each plant rather than hack back one plant at a time (imagine you’re a tea picker!). Regular harvesting of shoot tips is what helps plants remain bushy and healthy, providing you with an extended cropping period. Harvesting will begin from about the start of June and, given a warm summer, will continue right up until October when plants will slow down and die off with the return of cold weather.

Excess basil can be dried for winter use. To do this, tie bunches of the herb upside down in a cool, dry and dark place until they have fully dried out (this should take about a week). Once dry, flake up the leaves and fill airtight jars or containers. Basil may also be frozen or made up into bulk batches of pesto or pasta sauces, again for the freezer. Putting some basil aside for the winter is a great way to brighten up dark, dank days when the soul longs for a taste of summer.

Month-by-Month

  • January

    Prepare the ground for spring. Dig in well-rotted garden compost or manure to improve drainage and increase available nutrients.

  • February

    Finish preparing the ground and order in new propagation materials such as pots and multipurpose compost ready for sowing.

  • March

    Sowing can begin this month for plants that will be kept indoors. The light levels are bright enough to ensure a good, even crop.

  • April

    Begin sowing basil under cover, either in a warm greenhouse or on a windowsill. Maintain a minimum temperature of 15°C.

  • May

    Plant out young basil plants at the end of the month. By this time the soil will have warmed up and the danger of frost passed.

  • June

    Finish sowing new plants by the end of June. Outdoor-sown basil will benefit from the protection of a cloche in northern gardens.

  • July

    Regularly pick the stem tips to encourage plants to bush out and produce even more leaves. Enjoy basil fresh in salads for a real treat.

  • August

    Continue harvesting your basil to get the most from the plants. Pinch out flower shoots as soon as you see them.

  • September

    Plants may begin to slow down towards the end of September as the heat of summer recedes. Allow some to flower for the bees.

  • October

    Dig up the remaining basil plants before the first frost and dry them upside down under cover to enjoy preserved leaves during winter.

  • November

    Clear away the last remnants of basil, which will likely be a mushy mess after the first frosts. Remove dead plants to the compost heap.

  • December

    Order in the new seed catalogues and start planning what basils you'll grow next year. Pick a few of the unusual varieties for interest.

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Perfect Partnership

Perfect Partnership

The distinctive and varied aromas of the many types of basil are due to the complex interaction of essential oils within the foliage. The scent of ordinary sweet basil, for example, is similar to that of cloves, thanks to the dominance of eugenol, which is found in both. Similarly, limonene, the chemical that gives lemon peel its distinctive, fresh and tangy aroma, is also found in lemon basil.

All these essential oils have another welcome effect in that they repel a number of common insect pests. Mosquitoes, asparagus beetle and other common flying pests can’t stand basil, while other attractive and beneficial insects are actively drawn to it, including many species of butterfly and bees. This makes basil a powerful plant for companion planting. Position it next to fruiting crops such as tomato, peppers and chillies and you should experience fewer problems and an increased yield. Basil can be planted alongside asparagus beds each summer to thwart asparagus beetle while providing a tasty bonus crop.

Related Forum Topics

Basil: Varieties To Try

  • Sweet Basil

    The most popular basil with a distinctive sweet aroma that’s won it a place in many dishes. Look out also for the variety ‘Genovese’.

  • Lemon Basil

    The oval leaves with an intense lemon zing can be used in a multitude of dishes, particularly with chicken and fish. Also makes a refreshing herbal tea.

  • Lime Basil 'Mrs Burns'

    What a versatile basil this is! The lime-flavoured leaves can be eaten raw in salads or cooked up in sauces to impart a zingy tone. Or brew up a healthy herbal tea.

  • Thai Basil

    Its spicy aroma is somewhere between that of liquorice and cinnamon, making it great for Asian cooking. The plants grow to a good size.

  • Cinnamon Basil

    The strong cinnamon taste of this Mexican basil is the perfect accompaniment to many vegetables and soups. It looks stunning, too.

  • Red Rubin

    A purple variety of basil forming beautifully smooth, dark foliage that’s incredibly eye catching. Grow it amongst the flowers.

  • African Blue

    The perennial, purple-leaved basil that makes a stunning house or conservatory plant. Enjoy the leaves like any other annual basil.

  • Greek Basil

    Tiny leaves on a compact plant make this an unusual curiosity. Ideal for container growing or for pots on the kitchen windowsill.

  • Siam Queen

    Extra-large leaves with an intense liquorice flavour are borne on large, vigorous plants that look as good as they taste.

  • Purple Ruffles

    This showy variety has ruffled and fringed leaves with a dark purple colour. Plant it in among the bedding plants for contrast.

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Perennial Favourites

While most basil plants are grown as annuals, some perennial varieties are available for cultivation, providing a year-round crop of aromatic leaves. Like its annual counterparts, perennial basil originates from tropical regions of Asia, so it isn’t hardy and needs as much sun as possible. Perennial basil is sold as potted stock ready for transplanting into a larger container. Grow it in a container of John Innes No. 2 compost, keeping plants outside in a sunny and sheltered position for the summer. Move plants under cover when the weather cools off, maintaining a bright environment and a minimum temperature of around 10°C; a porch or conservatory is ideal for this. Reduce watering for the winter to give your plant a rest period.

Unlike annual varieties of basil, perennials tend to have a slightly rougher texture and a subtler flavour, but as they can be picked in the depths of winter when annual basil isn’t available, they make for a great fresh herb. Look out for the widely available perennial variety ‘African Blue’. It has pretty purple-tipped leaves and purple veins, making it an attractive addition to any garden. Leave a few stems unpicked so that they can produce their stunning spikes of mauve flowers in summer. It will carry on producing more leaves after it’s bloomed.

Basil

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