What supermarket basil can teach us - and how to grow it successfully

If you ever buy pots of supermarket basil, you’ll have noticed how the plants often look a bit grumpy after just a week or two. If you’re worried that this might be your fault let me reassure you: it rarely has anything to do with your growing skills! Supermarket basil is basically planned obsolescence - a ‘product’ (how I dislike that word) designed for a short life and regular replacement.

Before I look at three ways to grow happier, longer lasting basil, let’s look at why supermarket basil is so short lived. It can teach us some useful things about plant spacings and pot sizes.

To grow full sized, healthy basil in the ground, each plant is normally spaced about 10 inches / 30cm apart. Compare this to supermarket basil: in the pot that sits in front of me as I write - just 8 cm / 3 inches in diameter - I can count around 50 plants. There is literally less than 1cm between each plant!

Close spacing like this is a useful technique to get a good yield in quick time - and enables a relatively large amount of basil to be picked from the small pot. I use the technique myself with some salads and herbs to get a quick harvest of tasty baby leaves - like this coriander, pictured below.

Coriander seeds (from a spice pack) sown closer for a quick harvest of baby, tasty leaves.

The downside of close spacing is that the plants quickly use up all the available nutrients and root space. As they do, they lose condition and vigour - and growth slows. It works - but only if the plants are picked relatively quickly.

2. The small pot.

The small size of the supermarket pot poses severe limits on the space for the roots and the nutrients available. Small pots also can’t hold much water, making supermarket basil plants prone to dry out, particularly on a hot day. Plants that don’t have enough water get stressed and weaken - and their flavour is often impaired. If you’ve ever noticed your supermarket basil tasting a bit bitter or less pleasant after a few weeks, this might be why.

How to grow healthy, longer lasting basil

To grow healthy, longer lasting basil, we just need to use a larger sized pot and give the plants a bit more space. Basil also needs warmth to grow well (here, in the North East of England, I have to grow basil inside pretty much all year round), a good quality compost / potting mix, and regular watering (see my watering experiment at the bottom of this post).

Here are three ways to grow longer lasting basil.

1) From a pot of supermarket basil

The easiest and quickest way to grow basil is to buy a supermarket plant, split it up and repot it in a larger container.

• Fill a larger pot - anything from 2 - 5 litres (½ - 1 gallon) - with good quality, multipurpose compost / general purpose potting mix.

• Remove the supermarket basil from the pot and gently tease the plants apart. There’s no need to separate them into individual plants - clumps of two or three will grow fine together, and means less root disturbance.

• Carefully move the clumps into the larger pot, firming the soil around them so that the plants are securely anchored.

• Give the plants a good water.

• Keep them out of strong sun for 24 hours - just to let them settle in - and then put them on a bright window sill inside. Or, in warmer climates, you can put them outside if you have a sunny, sheltered space.

How long will your repotted basil grow productively for? This depends on various things including the size of the pot you moved them into, the quality of the compost, the weather and the condition of the supermarket plants you bought. In my experience - although nothing is ever guaranteed in gardening! - the plants will normally grow well for six to twelve weeks, occasionally longer.

2) From cuttings

You can take cuttings from any supermarket or other basil plant - or even use the stalks from a fresh pack of supermarket basil. This short video (a short extract from one of my online courses) shows you how to get started:-

After a couple of weeks the stalks will have grown roots and look similar to the photo below (although the photo is actually a mint plant) - and then you can pot it up in good quality compost in a larger pot. If you take four or five cuttings and move them all into one three or five litre pot you should get a nice crop of basil over 6 to 12 weeks.

3) From Seed

Most supermarket plants are Genovese basil, which is the classic and most common Italian variety.

However, if you grow your own from seed, you have access to many other varieties most of which are rarely - if ever - seen in the shops including lemon basil, dark opal basil (a pretty dark purple variety), Greek basil, cinnamon basil, Mammoth basil (which, as the name suggests, has hilariously large leaves), Mrs Burns Lemon basil (very pungent lemon scent), or Thai basil (with a distinctive spicy and aniseed twist), to name just a few.

I like to sow a mix of different basil seeds about 1cm apart into a 3 litre or 5 litre a pot (Franchi Seeds sell this excellent mixed pack that make this easy). This produces a colourful mix that looks great in the pot and on the plate. After sowing, I thin the plants out as they grow, eating the pretty baby leaves (which also taste amazing), and ending up with six to eight plants in the pot that I then leave to grow to a decent size. As you thin the plants, you can discover which varieties you like best and select which ones you want to leave to grow larger.

Left: basil grown from a supermarket pot; right from a mixed pack of basil seed.

How to grow bushy basil plants

She showed me how, if you pinch off a basil stalk just above a pair of leaves, two stalks will regrow from the leaf node, just below the cut. This helps to encourage a bushier, more attractive plant that also produces more fresh growth - and helps prevent stalks growing long and lanky.

When repotting supermarket basil, I let the plants settle for a few days and then pinch out all the tips (which I use in the kitchen, of course) to get the plants to bush up.

The best way to water basil? An experiment…

Most books say that basil is best watered in the morning as it doesn’t like to have wet roots overnight. I’ve followed this advice over the years and normally had good results.

Recently, however, I saw this interesting post by Leanne Kilroy that reported great success by placing the pot of basil in a bowl of water, kept topped up. This surprised me as pots sitting in water will often become waterlogged - and conventional wisdom is that basil hates waterlogged soil as the roots definitely need air to breathe. The most likely explanation is that - in a terracotta pot and with a free draining compost - the top half of the compost doesn’t soak up enough water to become waterlogged, ensuring the roots still have plenty of oxygen to breathe. While, at the same time, the topped up water reservoir will prevent issues of the plant drying out on hot days.

I’m always keen to learn and share the best way to grow plants in containers, so I thought I’d test this approach. I’ve set up two terracotta pots (as Leanne used), one sitting in a bowl of water and one watered in the conventional way. Alongside I’ve also got basil plants in a plastic pot, also sitting in a bowl of water, to see if it is the greater porosity of the terracotta that makes bowl of water work.

Here are the three pots today, just three days after planting. It will be interesting to see which grows best.

Basil on left sitting in bowl of water, the one in the middle will be watered from the top.

If you have any favourite basil varieties, tips for growing basil, or other basil growing experience (successes or disasters!), I’d love to hear from you in the comments.