How to grow basil

You’ll get the widest choice of varieties if you grow basil from seed, and packets are readily available in garden centres and from online retailers. If you don’t have the time or space to grow from seed, you can buy plug plants and young plants from similar outlets, although the choice of varieties is more limited. Many supermarkets also sell pots of basil plants but these are designed for short-term harvesting – the pots usually contain lots of thin, overcrowded plants that tend to succumb to fungal diseases or soon start flowering, although they may survive if divided up and repotted promptly. 

If you want to grow basil as microgreens, you can either use seeds from a standard packet or you can buy packets specifically for growing microgreens, which usually contain larger quantities of seed.

It’s best to start basil off indoors in warm conditions, to give a longer growing season. Sow seeds from March through to July in small pots or modular trays of damp peat-free seed compost. Scatter the seeds thinly on the surface, then place in a propagator or cover with a clear plastic bag. Seeds will germinate well at a temperature of about 20°C (68°F). If you sow several small batches a few weeks apart, you’ll have harvests over a longer period. See the video below for information on sowing basil indoors in early spring.

​

Move basil seedlings into individual pots once they have several leaves

Sowing microgreens

You can also sow basil seeds more densely in trays for harvesting as microgreens. They will be ready to harvest within 10 to 14 days, depending on light levels and temperature. Sow at any time of year, keep on a warm bright windowsill and water regularly – you’ll soon have tasty, nutritious seedlings to snip and scatter in salads and other dishes. If you choose a purple variety, they’ll add a splash of colour too.

Basil can be sown outdoors but results are likely to be less successful than indoor sowings. If sowing outdoors, wait until early summer, once night-time temperatures consistently stay above 10°C. Sowing outdoors gives a shorter growing season and is only suitable for warm locations. Growing in containers is often more successful than in the ground, as they provide the free-draining conditions basil needs, and plants are easier to protect from slugs and snails.

Position the container in a warm, sunny location, and fill with peat-free multi-purpose or seed compost. Sow the seeds thinly on the surface, without covering them. Alternatively, sow directly into free-draining soil in a warm, sunny spot. Thin out the seedlings until they are 10–20cm (4–8in) apart, removing the weaker ones first. Overcrowded basil plants tend to start flowering sooner, bringing harvests to an end.

Water newly planted basil well until it's established, then water during dry spells to keep the soil or compost evenly moist. Plants in greenhouses and containers will need regular watering. When watering, try to avoid splashing the leaves and water in the morning if possible, as basil hates having wet roots overnight. Basil may start to flower sooner in dry conditions.

When growing basil in the ground, there’s usually no need for feeding, but plants in containers can run short of nutrients, so you could apply an organic-based, balanced liquid fertiliser to boost leafy growth. Avoid using potassium-rich fertilisers like tomato feed, as these encourage flowering.

Although basil is usually grown from seed (see Sowing above), it’s easy to grow new plants from softwood cuttings taken during summer. Snip off a non-flowering shoot just below a leaf, remove the lower leaves and pinch out the tip, then stand the cutting in a jar of water. It will quickly form roots and can be planted in a pot of peat-free multi-purpose compost after just a few weeks. Basil cuttings can also be rooted directly in compost.