Basil or sweet basil (Ocimum basilicum) is an aromatic annual herb in the mint family. It is a tall, leafy plant that’s full of flavour and can be used in many tasty ways.

It is rich in Vitamins A, B6, C and K along with minerals such as manganese, iron and magnesium. It also has potential to be used in insecticides including as a mosquito repellant and has antibacterial properties.

Relatively easy to grow given warm, sunny conditions, there are many varieties to tempt. Consider sweet basil, lemon basil or purple basil, as well as species including Thai basil, which is a perennial species. Why not plant all of them in the herb or vegie garden or in pots.

Basil is eaten raw and is a traditional flavour companion to tomatoes in salads, on sandwiches and for topping a Margherita pizza. It is also delicious blended with nuts, garlic, oil and Parmesan cheese as pesto.

Follow our seven easy steps to successful basil harvest including tips along the way.

When to plant

Basil can be grown in most parts of Australia. Check with hardware and garden centres for varieties available in your local area. It’s a warm-season annual but in warm, frost-free climates may be longer lived.

  1. In cool to cold regions grow basil from October onwards, once the risk of frost has passed.
  2. In warm and temperate regions grow basil from September onwards.
  3. In subtropical and tropical climates basil can be grown most of the year.

Location

  • Basil grows best in full sun or with light afternoon summer shade in hotter climates to reduce stress.
  • Select a protected position as the leaves can be scorched by hot dry winds.
  • In cooler climates, ensure your basil has at least six hours of sun each day.
  • Basil prefers soil that holds moisture well. Keep it growing quickly with regular watering.
  • Grow basil in a herb garden, vegie bed or container. Basil can be grown in small pots on a sunny kitchen windowsill.

Soil

Get the soil right to harvest a bumper harvest of tasty basil.

Follow our steps for easy soil preparation.

  • Basil tolerates a wide range of soils but prefers a beautiful, rich soil, full of organic matter.
  • Improve the  soil by digging in home made compost and organic matter and/or Seasol Super Compost. For a no-dig option consider Seasol Liquid Compost.
  • Soils that are highly acidic benefit from the addition of some lime.
  • In areas with poorly drained soils, grow basil in raised garden beds or containers. When growing basil in containers use a premium potting mix such as Seasol Advanced Potting Mix which has everything in the bag to help basil flourish.
  • A soil rich in nutrients helps build strong plants so add Seasol Plant + Soil Booster (100g per square metre) and a fertiliser such as PowerFeed Controlled Release Tomatoes & Vegetables.
  • Water in well and let the soil rest for a week or two.

Step 1 – Sowing seeds

  • Grow from seed sown thinly into a punnet or seed tray filled with seed raising mix such as Seasol Seed Raising & Cutting Potting Mix.
  • Seeds can also be direct sown where plants are to grow. Sow seeds at 5mm deep and lightly cover.
  • Water in well with Seasol GOLD or Seasol as this will help to increase seed germination rates. Soil should be moist but not wet, so check soil moisture daily to ensure basil seeds have the right conditions to germinate.
  • If growing seeds in cooler weather ready for when the weather warms, protect young seedlings from frost by leave them inside in a warm position.

Step 2 – Germination

  • Seeds take around five days to germinate when conditions are warm (slower rates in colder conditions) For faster seed germination rates in seed trays, put them inside on a heating pad.
  • Apply Seasol GOLD or Seasol weekly (mix 30mL of concentrate per 9 litres of water) as this will help to stimulate strong root development and healthy growth.
  • Protect from snails and slugs especially while shoots are emerging (See “Things to watch out for” below).
  • Pinch leaves from the tips of your basil as soon as the plant has two sets of true leaves. This encourages your basil to grow full and bushy.

Step 3 – Baby basil seedlings

  • Basil tends to grow in clumps as the plants will hold each other up together, rather than flopping over. If overcrowding becomes too great, select the strongest seedling and thin out or transplant the rest.
  • If not transplanting, use scissors or tweezers to thin out seedlings to avoid disturbing young roots.
  • Basil seedlings need to be feed for a bumper crop, so liquid feed with PowerFeed PRO SERIES for Tomatoes & Vegetables every two weeks. Increase the application rates from 20mL to 50mL of concentrate per 9 litres of water as the plants mature.
  • Check soil moisture daily and water as needed.

Step 4 – Planting out basil seedlings

  • After two to four weeks transfer into the garden into prepared soil or into a larger pot when seedlings have leaves and they are large enough to handle.
  • Plants should be placed around 20cm apart in rows of 15cm apart.
  • Seedlings are also available from hardware and garden centres, ready to plant in pots or the garden. Follow the instructions for plant according to the directions on the plant tag.
  • Check the moisture level of the soil daily and water when needed

Step 5 – Basil plant growth

  • Keep developing plants hand weeded or hoed and well watered.
  • Mulch around each plant with organic mulch such as sugarcane mulch, lucerne or pea straw. This helps suppresses weeds and retain soil moisture.
  • Check soil moisture daily and apply PowerFeed PRO SERIES for Tomatoes & Vegetables and Seasol GOLD or Seasol regularly for tasty basil.
  • Bolting can occur when the plant flowers prematurely (often due to stress of soil moisture or very hot temperatures).

Step 6 – Early basil harvest

  • Basil can be harvested at any time. by pinching out or cutting a few leaves, this also stops the plant from becoming leggy.
  • If you don’t need the leaves, give to family and friends or swap for other produce.
  • Always make sure to leave enough leaves on the plant for it to recover and grow more leaves.
  • Remove any weeds and top up mulch as it can break down quickly during the warm summer months.

Step 7 – Basil harvest

  • Basil leaves can be harvested from about eight weeks after sowing if plants are growing strongly.
  • With good care, plants will grow for many weeks through summer.
  • Once flowering begins, harvest plants, strip leaves from stems and use the leaves fresh or dry for future use.
  • If garden space allows, leave some plants to flower to set seed and also to provide nectar for pollinating insects.

Things to watch out for….

If basil is growing in warm, sunny conditions, it is a trouble-free crop. Over fed with high nitrogen fertilizer it will produce large, lush leaves that are highly attractive to sap-sucking pests such aphids and white fly.

  • Aphids attack foliage. Squash or hose off infestations.
  • Slugs and snails can attack seedlings. To protect against these pests check plants regularly and use a snail trap or pet and wildlife safe baits based on iron phosphate.
  • White fly is seen as small white fly-like insects resting on leaves but fly into the air when disturbed. Prevent an attack by avoiding overuse of fertilisers and keep plants in airy, well-ventilated locations. Additional water will alleviate stress caused by white fly feeding.
  • Bolting can occur when the plant flowers prematurely (often due to stress). Plants do however reach flowering in late summer. Pinching out growing shoots and tip pruning flower buds may extend the period of leafy growth however, once plants enter the flowering phase, harvest stems to use the foliage for example to make pesto.
  • Mildew and leaf spot can affect foliage especially towards the end of the season. If white mildew is seen, remove plants.
  • Frost is highly damaging to basil which is not cold tolerant. Harvest basil before the first frosts arrive.