Basil is a classic herb beloved the world over and so easy to grow in the garden or in pots on a sunny patio near the kitchen, ready to be harvested and used in a myriad of dishes.
It belongs to the family of mints – lamiaceae – and is an annual herbaceous plant.
Growth habits and planting needs
First select the variety of basil you wish to grow.
There are so many varieties of basil to choose from, each with their own distinct aromatic flavour. The size and shape of the leaves also varies from the large leaves of the Genovese Giant basil and Lettuce leaf basil to the tiny leaves of the Dwarf bush basil.
The Seed Collection Australia has 13 different varieties of basil seeds available. They are heirloom, open pollinated, non-hybrid and non-GMO seeds with no chemical treatments You can view information on these at the following link:
Below is an an image of the familiar sweet basil, Ocimum basilicum.
To contrast, one of the purple cultivars of Ocimum basilicum is ‘Dark Opal’. The leaves at the top are the deepest purple with the lower leaves a lighter green and it has cerise pink flowers. It is slow growing and slow to flower. Purple basil gives its striking colour and strong flavour to infused oils and dressings, salads, desserts and other dishes where basil is used.
Basil needs a warm sheltered site that gets 6-8 hours of full sun a day and a rich, well drained soil. If your local climate is prone to many days of extreme heat in summer a semi shaded site may be needed to offer some protection in the heat of the afternoon.
Basil can be grown in wide range of soil types from acidic to alkaline but optimally basil prefers acidic soil with a pH range 5.5 – 6.5. Test your soil and then amend it.
Prepare the soil by digging in well rotted cow manure and aged compost to a depth of 15 cm. If planting in pots, add a little coir, (coco peat) this will acidify the soil as well as help soil structure and the water retention in the potting mix.
Sow seeds in trays in the greenhouse or sow directly or transplant seedlings into their final position in the garden after the last the last frosts when the soil temperature has reached 21º C (70º F). This is important because basil is very frost sensitive. Ideally it should be planted mid spring to early autumn.
Sow the seeds thinly to a depth of 5 mm and cover very lightly. Press down and keep moist.
The seedlings should emerge in 10 – 14 days.
Thin out to space the seedlings 30 cm apart to allow the mature plants enough space as they can grow to 50-60 cm in height. Water with diluted Seasol to encourage root formation.
To create a bushy rather than leggy plant, make sure to pinch out new growth and so encourage side shoots. Begin this when the plant is 15 cm tall. Look for two large leaves near the bottom of the plant that have a second set of small leaves in the node, as in the image below, and using small scissors or fingers, trim off the growth leaving about 1 cm on the stem above the leaves.
The small leaves will then grow into new side shoots and by continuing to do the same all over the plant as it grows you will ensure a bushy plant with maximum leaf growth. In this way you are not only improving the growth and longevity of the plant, you are continually harvesting fresh leaves for your culinary use.
You can even propagate new plants from these trimmed pieces by putting them in a jar of water on your window sill until roots emerge along the stem.
During summer basil will grow more quickly making harvesting more essential. If the plant is allowed to go to flower then the energy of the plant will go into seed production at the expense of leaf quality. Continual tip pruning will prevent this.
If you choose to let some plants go to flower, you can pick the delicate blooms for your salads or to use in pasta dishes or as garnishes. The basil flowers can be used to make a mild tea. They can also be used to infuse vinegar and oils for dressings. Below are some images of the delicate and beautiful basil flowers that are so attractive to bees.
Like all members of the lamiaceae family, basil likes to be kept moist but not wet, so if the summer days are hot make sure to water your basil in the early morning and mulch around the plant to keep out weeds and conserve moisture.
To maintain a healthy growth fertilise with a liquid seaweed fertiliser every 2-3 weeks.
Basil is a good companion plant for tomatoes, pepper, eggplant and lettuce as it improves their flavour and growth and repels flies and mosquitoes.
Perennial basil is another variety that is useful as a companion to attract bees. They absolutely love this basil and it flowers constantly. It is a vigorous plant that can be pruned by a third in spring and autumn to encourage new growth.
To promote growth basil needs to be harvested weekly at first and as the season warms up it may need to be harvested every day to prevent it bolting to flower.
The best time to harvest basil leaves is in the early morning while the leaves are still cool.
When harvested, the basil leaves can be stored in a number of ways:
- Place the harvested stalks into a jar of water like a bouquet of flowers on a bench top for in a few days.
- Alternatively, cover the leaves with kitchen paper and store in plastic bags like Fresh and Crisp bags in the crisper drawer in the fridge.
- To store for an extended period of time, freeze the washed and dried basil leaves in airtight clip lock plastic bags in the freezer section of the fridge.
- Basil can also be dried by tying bunches of leaves then covering in paper bags that have holes pierced in them, and hanging the bags in a dark, cool and airy place. Once dry remove and place in airtight containers in a dark cupboard.
Use your own basil leaves to make the most flavourful homemade pesto for your pasta and other dishes.
Just click on this link for the recipe for Classic Pesto Genovese: