How to plant, grow and harvest basil
An attractive garden plant that’s easy to grow and is an essential ingredient in a multitude of dishes. That’s basil!
What you need to know about basil
Name: sweet basil, basil, Mediterranean basil (Ocimum basilicum)
Plant type: shrub-like fast-growing annual or perennial
Height: 30–50cm, sometimes larger
Foliage: broad oval with a slightly pointed tip, often “‘wrinkled” along the venation, glossy pale to bright green, soft. Can be slightly toothed along the margins.
Climate: sub-tropics, warm temperate, warm spots in cool temperate. During winter in the tropics.
Soil: average to good quality garden soil, sandy soil if extra organic matter is added. Must have good drainage—doesn’t survive well in heavy or waterlogged soil.
Position: full sun in cooler regions, some shade in hot areas.
Flowering and fruiting: long white flower spike with small, pretty white to pink flowers along the stem. Appear generally from mid-summer.
Feeding: in quality soil or potting mix additional feeding isn’t essential. Leaf flavour is often more intense if left unfertilised.
Watering: best if it receives reliable moisture during warm periods. Moderately dry tolerant once mature, but wilts quickly, and leaves can scorch.
Appearance and characteristics of basil
There are few herbs as versatile as basil. It’s used fresh in stir-fries or pasta sauces, as a tasty garnish, in salads and of course as a vital ingredient pesto! Basil has a long history of use in the kitchen, and is also used medicinally and in cultural and religious ceremonies around the world.
Most people associate basil with Mediterranean cuisine, but it’s thought that the plant actually originates from the warmer areas of Asia. The varieties with the more intense flavours and spiciness tend to be used in Asian cooking, whereas Mediterranean cuisine leans towards the “sweet” varieties.
Basil is a small, usually dense shrub with a very upright branching habit. It tends to be quite conspicuous in the garden due to its distinctly-coloured foliage.
Basil usually flowers from mid-summer. Unlike some herbs, it doesn’t die as soon as it flowers, but foliage will start to thin. Although generally treated as an annual, basil can remain productive for months during flowering, and in the right climate and position can be trimmed back to reshoot. Some varieties and species are considered to be longer-lived perennials.
All types of basil are very easy to grow, and most do very well in pots or window boxes, or even indoors on a sunny windowsill.
Sweet basil is the most well-known and commonly grown basil, but there are a few other very useful and popular varieties.
Thai basil (O. basilicum var. thyrsiflora or var. ‘Anise’): distinct liquorice-like aroma with spicy undertones. Leaves narrower and more pointed than sweet basil. Stems often a purplish colour. Flower spikes purple with pink flowers.
Spicy globe basil (O. basilicum ‘Spicy Globe’): dwarf form. Neat compact shape to around 30cm tall. Smaller leaves and flowers than sweet basil, more spicy and minty.
Holy or sacred basil (O. sanctum syn O. tenuiflorum): aroma is more minty, with musky hints. Can be used in cooking but most often used during Eastern religious ceremonies and festivals.
Perennial basil (Ocimum gratissimum): Often called “clove basil” for its distinct clove aroma. Can be grown successfully for a number of years. Narrow leaves. Flower spikes are purplish with white-pink flowers.
Basil can be planted for many uses, including:
- Improve soil at planting time by blending through compost or well-composted manure.
- Although not essential, adding a controlled-release fertiliser will be beneficial.
- Pinch out new growth tips at planting time to encourage bushiness.
How to plant and grow basil
1. Climate: In most regions basil will be grown as a warm-season annual, or occasionally as a perennial. In the tropics, however, it should be grown as a cool-season annual, as it won’t tolerate extreme heat. Basil has no frost hardiness.
2. Sunlight: Basil is happiest in a warm spot in full sun, however in hot regions it will benefit from some shade. It will grow quite well in part-shade or diffused light, but it tends to stretch and become leggy.
3. Aspect: The stems of basil tend to be quite brittle, so are easily broken by wind. The leaves can also be scorched by dry or hot winds, so select a protected position.
4. Soil or potting mix: Basil can grow very well in almost any free-draining soil, but adding compost or composted manure, especially to sandy soil, will give better growth. This is largely because it will improve the soil’s ability to remain moist, which basil likes. Basil will not tolerate wet soil or heavy soil. In pots, use an organically certified potting mix or one that's tailored for edibles.
5. Watering: The simple rule is to ensure reliable moisture, especially during warm times.
Uses for basil
Basil can be planted for many uses, including:
- Handsome small shrub that’s both ornamental and practical.
- Multitude of uses in the kitchen.
- While in flower, it’s excellent for attracting pollinators.
Caring for basil
Basil is a relatively care-free plant to grow. Liquid feed with an organic or seaweed-based fertiliser across the growing season. Ensure that any leaves are thoroughly washed before eating.
To extend leafy growth, pinch out flower shoots as they start to develop. When growing in pots, rotate your pot by 90˚ once a week to keep your plant nice and evenly bushy.
Pruning and harvesting basil
You’ll find that regular harvesting of basil keeps your plants well pruned. When taking cuttings, try to avoid picking from one side only, otherwise your bush can become lopsided.
Flower spikes can be pruned out as they develop. However, the flowers are edible, and make a nice addition to salads, or sprinkled over pasta.
At the end of the season, bushes of perennial basil can be pruned back hard. In warmer regions even sweet basil can be coaxed into a second season by pruning in autumn.
Diseases and pests affecting basil
Basil is prone to very few pests or diseases. It may be attacked by green looper caterpillars, which can easily be removed by hand. White fly may be an occasional problem.
How to propagate basil
How to grow basil from cuttings
Basil will grow readily from cuttings. Just stand them in a glass of water in a sunny spot and they will develop roots in no time. These new plants will still be running to the same timeframe for flowering as the parent they were taken from, so plants grown this way may flower very soon after planting. This isn’t a problem with perennial forms, but may make for a short productive life with annual varieties.
Growing basil from seed
Seed can be harvested from your basil and saved for next season, or bought in packets. Either sow in the garden into suitably prepared soil, or spread in a seedling tray filled with seed-raising mix and keep warm and moist. If sowing in trays, pick the strongest seedlings and plant out in batches a week apart to extend harvest time.
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Parsley: one of the most common herbs used in cooking, parsley is delicious and versatile.
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