Have you been tempted by the beautiful, lush, aromatic basil plant on the shelf at the supermarket and bought it to grow on, only to be somewhat disappointed when it wilts and turns somewhat black when you get it home and place it on your windowsill?
In theory, you could grow this supermarket basil and harvest it for the rest of the season with enough leaves to go round for Italian dishes and even dry or freeze the rest for Winter; however, they often die back before this can happen.
It can happen even if you are particularly diligent about watering it and making sure it’s in bright light, and you can even question whether you’re just bad at growing herbs!
Don’t worry, because it’s not you, it’s the basil! Once I explain what actually happens (the supermarket basil is almost set up for failure).
I’ll tell you what to do so you can have a harvest of basil ongoing from your supermarket purchase.
What’s Actually Inside That Basil Pot
So we need to think about intent here. When basil is grown commercially for the supermarket, the goal is to make it look as gorgeous as possible on the shelf so that you buy it…rather than longevity. What the growers actually do is sow large quantities of seed together in a small pot and grow them in the best greenhouse conditions with perfect temperature, humidity, and supplement the lighting with grow lights, hence why they look so good when they hit the shelves.
So what you’re actually buying is lots of stressed seedlings crammed into a small pot with a small amount of compost, so that when you get them home there are starting to be root-bound and exhaust the compost of nutrients, hence why they falter.
Let’s think about what this means in practice:
- The roots don’t have anywhere to grow, and they circle the pot without space to expand into more soil.
- The compost volume is so small that it dries out quickly on a hot day.
- The nutrient reserves are depleted from all the individual basil plants competing with each other.
Then it gets a bit of a culture shock when it arrives in your house with lower humidity, lower light intensity and fluctuating temperatures. It reacts by wilting due to shock.
This is a sneaky little trick by the supermarkets, but don’t worry, because there is a solution.
The Fix for SupermarketBasil: Split and Repot
Fortunately, the solution is very time-efficient and often only takes about 5 minutes, so I do it every time I buy basil from the supermarket.
What you are going to need:
- About two or three small to medium-sized pots with drainage holes in the base.
- Good quality potting compost (peat-free multipurpose works well), or you can add some perlite for better drainage if you tend to overwater plants.
- A watering vessel at the ready.
What you need to do…
First of all, remove the basil from its supermarket pot. What you may find is a dense tangle of roots that has filled every inch or centimetre of the pot, which tells you the plant was struggling.
What you need to do is gently split the root ball apart into two or three separate sections. Don’t worry about being too precise, as basil is quite resilient at this point, and some root disturbance is far less damaging than leaving the basil overcrowded and wilting.
You need to pot each little section of basil into a new container with new compost. I generally find I have enough sections for three pots.
Hot tip: If you live in a hot climate, use a slightly bigger pot as it dries more slowly and use either a plastic or ceramic pot as they are impermeable and dry more slowly (unlike clay or terracotta, which are porous).
Pot each section up and bury the roots and firm it gently around the basil…enough so that it can stand upright, but not too much that you compact the compost too much that you push the air out of the soil.
Give the compost a good soak to help with transplant shock. The goal of watering should always be to ensure that the compost is evenly moist to prevent wilting.
That’s all there is to it. Within around 10 days or so, you’ll see a difference with stronger stems, larger ne leaves (that smell aromatic), and the basil no longer wilts all the time because it has more soil and therefore more water.
Where to Put Your Basil After Repotting
This is where a lot of people make the second mistake with basil. Placing it somewhere in the house that you’d think would logically work, but doesn’t in practice.
What basil needs is genuine warmth and bright light to thrive properly. I have seen people put basil on cool north-facing windowsills because it looks light enough to us, but it’s not bright enough for the basil.
Here’s what works best…
- A south or east-facing window sill that gets some direct sunlight.
- If outdoors, then a sheltered spot (once the night time tempertures are reliably above 10°C or 50°F).
- If basil is planted outdoors during a warm summer its likely to grow much more than it can indoors on a windowsill.
- Keep the basil away from any cold draughts.
One caveat that I have learned from my own experience is that on days when the temperature spikes suddenly, then even well-established basil can wilt dramatically in sudden afternoon heat, particularly if it is in a south-facing window.
Do not worry, as the basil is temporarily losing water through its leaves faster than the roots can replace it. What the basil is doing by wilting is reducing the surface area of the leaves for transpiration to slow down water loss as it adjusts to the shock of a sudden high temperature. Do not be tempted to water it if the soil is already moist!
Typically, the basil perks up later in the evening when the temperature has cooled.
I would water your basil in the mornings if there is a hot day forecast, to charge it with water to prepare for the hot day ahead. Once the basil has acclimated to the higher temperatures, it should be fine.
Watering After Repotting
Your basil has a higher demand for water compared to most herbs, but the single biggest mistake, if you think your herb is dying, is to overcompensate with more water.
Here are the rules that I follow…
- I water thoroughly when the top inch of the compost feels dryer to the touch…not necessarily bone dry but still damp. Give it a good soak.
- If in doubt, I pick up the pot to assess the weight. If it’s heavy, I know the soil is still damp, but if it’s lighter than expected, I know the soil is dry and needs watering.
- I always water at the base of the basil rather than the leaves, as damp foliage can cause fungal problems.
- You need to avoid putting your pot sitting in a saucer of water, as this can cause root rot.
- When it’s very hot, I check whether my basil needs watering almost every day.
The goal with watering is to soak the soil, then allow it to dry slightly rather than a saturated pot of compost. Basil roots actually need oxygen as much as water, so keeping the soil too damp can cause it to wilt as much as keeping it too dry, hence the need for balancing.
Should You Pinch It Back?
Yes, absolutely, and this is the most beneficial thing you can do to extend the basil’s harvest. What basil wants to do is to produce flowers and then go to seed. If you let it flower, then its energy is going to go to producing seeds rather than the tasty green leaves.
If you pinch out the growing tips, then you prevent the flowers from forming, and your basil directs its energy to growing more tasty leaves.
I do this as often as every 10 days or so, to keep the basil at around 6-8 inches in height, even if I don’t intend to use the basil right away (I freeze it or sometimes dry it for using later)
Doing this consistently results in a much bushier basil plant with even more leaves!
One More Thing Worth Knowing
Even with the perfect care, basil is an annual plant rather than an evergreen and therefore completes its life cycle in a season, and it’s going to die back, whatever you do.
Whilst basil is not immortal, you can significantly extend the harvest and the amount of leaves with these tips.
Have you tried splitting and repotting your supermarket basil? I’d love to hear how it went, so drop me a comment below!