The Ultimate Guide to Growing Basil

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Inside: Do you want to grow your own basil? Then check out this ultimate guide to growing basil including types of basil, growing from seed and harvest.

There’s no shortage of herbs you can grow indoors and a lot you can grow outdoors.  One of the easiest to grow and tastiest to use is basil.  You can grow it indoors and outdoors, from seed or from smaller plants.  Plus, there are loads of varieties.  Let’s dive into the ultimate guide to growing basil!

Basil varieties

In total there are more than 150 types of basil (known as cultivars) but we won’t go into every one.  What we will look at are some of the most commonly found and what makes them distinctive.  Some have a bolder flavour while others are a little spicy, even sweet.  All of them are annual plants that are easy to grow – but more on that in a moment.

Boxwood

• Small leaves, keeps to a nice round shape (like a box hedge)
• Grows to about 12 inches high, 12-16 inches spread
• Strong flavour, ideal for pesto

Cinnamon

• Also known as Mexican spice basil, it has dark stems, narrow leaves and purple flowers
• 12-18 inches height and spread
• Sweet flavour that has hints of cinnamon and is great for baked goods

Dark opal

• Deep purple leaves and lilac-pink flowers
• 12 inch compact busy basil
• Anise-based flavour with a hint of ginger that is ideal for savoury or sweet dishes

Emerald Towers

• Bright green classic basil style leaves
• Grows in tall columns that can reach 24-36 inches high
• Liquorice taste with a hint of cloves

Genovese

• The classic basil with large, bright green leaves
• Grows 16 inches tall and spreads about 12 inches
• Strong, anise flavour with a sweet fragrance, it is used for everything from pizza to pesto

Greek

• Smaller leaves, tiny white flowers
• Swarf variety that grows around 8 inches high and spread so ideal for containers, edging or rockeries
• Strong, spicy fragrance and flavour that is ideal for dressings for salads, sauces, stews and soups

Holy

• Also known as sacred or Tulsi basil, it has darker green leaves mottled with purple
• Grows 12-14 inches in side
• Popular in Hindu religious ceremonies, it is used to make an immune boosting tea

Italian large leaf

• Largest leaves of any basil, bright green in colour
• Grows 24-30 inches, 12 inch spread likes a sunny spot in the garden or a windowsill
• Sweet and mild flavour, perfect for pesto and other sauces

Lemon

• Hybrid variety with narrow bright green leaves
• Grow s20-24 inches high and spreads about 12 inches
• Popular in Indonesian cuisine, it has a lemon scent and sweet flavour that is used in curries, soups and stews and even in salads

Lime

• Bright green leaves with narrow shape
• Grows 16-24 inches with 12 inch spread
• Light and citrusy, floral flavour that ads zestiness to salads, dressings, sauces and some desserts

Mammoth

• Large leaf variety also like lettuce with ruffled edges
• Grows 16 inches with 12-16 inch spread
• Spicy clove flavour with a sweet, pungent flavour similar to Genovese

Minette

• Compact plant with smaller leaves
• Grows to 10 inches so is ideal for borders or containers
• Sweet, anise flavour with a hint of cloves

Purple ruffles

• Similar to Dark Opal, it has dark purple narrow leaves
• Grows 16-20 inches tall
• Can be used interchangeable with Dark Opal basil

Siam queen

• Variety of Thai basil that has green leaves and purple stems
• Grows to 10-24 inches with a similar spread
• Sweet liquorice flavour that is great for curries, soups, stir-fries

Sweet basil

• One of the most popular varieties, it is also known as ‘common’ basil and has bright green leaves
• It grows around 24 inches tall and wide
• It has a full liquorice flavour which works well for salads, sandwiches and in sauces as well as pesto

Basil pot size to grow indoors

One of the most popular ways to grow basil is indoors.  This is particularly true in places like the UK where we have pretty cold winters – the plant just won’t survive outside.  So, growing it somewhere like a kitchen windowsill is perfect.

To start growing your basil indoors, you will want the right pot size.  The best container size for just a single basil plant is one that is 20-25cm deep (8-10 inches).  This holds around 9 litres of compost (or 2 gallons if you prefer).

You can use normal pots or even go for something like a self-watering style.  These have a reservoir system that holds water and allows the plant to suck it up through its roots as needed.  Some even have a water level indicator, so you know when more water is needed!

The reason that pot size matters is that basil is one of those herbs that tends to grow their roots vertically.  That way, they can grow taller and give plenty of leaves to harvest and use.

How to grow basil from seed

If you are growing basil from seed, you will want to start with a seed tray before moving your bigger plants into the larger pot.  To grow from seed, you should:

1. Get some compost or soil and add a little water until it is moist enough to cling together a little in your hand
2. Fill the seed tray to ½ inch below the top
3. Add a few seeds into each compartment of the seed tray
4. Sprinkle some dry compost over the top to cover them
5. Gently mist water into the compost
6. Pop a dome over them to keep the moisture in – if you don’t have this, you will need to keep watering them regularly until they sprout

Keep your seed tray somewhere warm but not too hot and check them every day.  Usually, the seeds will sprout within 3-5 days and little tiny shoots will appear.

Once the sprouts appear, take off the dome.  Move to somewhere with natural sunlight but not too hot and start to water regularly, usually twice a week depending on humidity.  Try to water from below – in other words, add water to the tray under the seed tray and let the seeds suck it up.  If the soil looks dry, mist a little more water onto it.

Pruning your baby basil plant

To get a bushy, healthy looking plant to put into your nice pot on the windowsill, there’s a bit of work to do in the middle. Pruning those baby basil plants is a key part in getting bushy, healthy adult plants.

It is important to prune basil early – it is called ‘pinching’ and involves removing leaves to promote growth and a bushy plant.  It should be done from the plant being about 6 inches high and has 3-5 sets of leaves.

If there are three leaves at the top then another two leaves further down, cut off the top three.  This might seem extreme, but it is the best way to get the plant to grow in the right way and not become leggy.

Once the plant is around 4 inches high, do the same again.  Don’t forget the leaves are still edible and can be used in your recipes so there’s no waste!

Transplanting basil

The final step to adult bail is to move it to the bigger pot you picked up originally.  Plants need plenty of room to grow, be healthy and product lots of leaves.  Without enough room, they become rootbound and often die.

You can move it after it has a few sets of real leaves and put into a pot around 4-5 inches in diameter.  It can stay there until there are roots sneaking out of the bottom.  Move it next to your larger, permanent pot.

How to grow from small plant outdoors

If you don’t want to mess around growing basil from seed, you can buy a small plant and grow it on outdoors or indoors.  These are the types you see at the supermarket or garden centre and are an inexpensive way to get a head start on your basil crop.

Once you have a small plant, pick a spot with lots of sunlight and warm temperatures but hide from the midday sun.

If you are planting in the ground, add some compost or other organic matter into the hole before the plant to five it a boost.  There should be at least 8 inches growing room per plant downwards and 12-16 inches between it and other plants.

Place the plant in the hole you have created and cover it with soil, pressing firmly around the top.  Add 1-2 inches mulch to help with moisture and water it regularly.

When and how to harvest

Ask my husband about harvesting basil and he knows one thing – he’s terrible at it!!  As a chef, his idea is to just cut off what he needs, when he needs it.  And what happened?  One dead basil!

You don’t need to harvest basil at a particular time, but it is best to do little and often rather than in big bunches.  Even if you don’t need it, you can dry it and chop up to store.  Aim to harvest around one third of leaves each month to keep the growth going.

To harvest, you can use herb snips or sharp scissors.  Cut just at the point where two large leaves meet.  Then you give the plant a chance to keep growing until the end of the season.

Basil microgreens

Some varieties of basil such as Genovese can be grown as microgreens.  This means they grow for a much shorter time but are a lot smaller when they are harvested.  They are a one and done approach too like cress.

With this approach, wait until the first full leaves are properly developed to make sure there is plenty of taste.  This usually takes 12-20 days.  Then you can harvest the smaller leaves.

Can you overwinter basil?

In many cases, basil is an annual plant.  That means it will grow for one growing season and then die off and not come back.  If you keep the plant indoors, you can overwinter basil and get a second year from it in some cases.  The key is to have plenty of sun and steady temperatures during the winter as it is very cold sensitive.

Grow your own basil

Basil is one of the easiest herbs to grow from seed and can also easily be bought in smaller plants.  You can have a plant all year long if you are careful about harvest and pruning it and sometimes even overwinter it.  There are lots of types of basil to choose from so you can experience with different flavours in your favourite recipes.