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Tips on growing coriander from the supermarket and how to keep it alive for longer. Use this technique to get several generous harvests from your plant and have fresh herbs all summer long. Full DIY video included.
You’re standing at the supermarket and deciding to get cut herbs or potted plants. Many of us choose potted plants because we hope to get a few harvests from them and keep the herbs fresher for longer. Unfortunately, once we buy those lush, green supermarket herb plants, they die within a couple of weeks. What went wrong? Is there some way to keep them alive? Many don’t know that each grocery store herb plant is grown differently and has a different natural lifespan. Understanding this will help you to keep all of those plants growing for longer – some even indefinitely. This piece focuses on growing coriander from the supermarket and what to do to keep the harvests coming.
Coriander, known as cilantro in North America, is one of the most popular supermarket herb plants. It’s probably the most challenging to grow, though, as many have already found out. After bringing it home and that first cut of leaves, it can sulk and whatever is remaining of the foliage fails to thrive. It looks terrible within a week or two, and eventually, you consign it to the compost pile. Despite previous attempts, there are a couple of simple things to keep your supermarket coriander alive long enough for a few good harvests.
How Coriander Naturally Grows
The trick to growing coriander from the supermarket is understanding how the plant grows. Each seed will germinate in about one to three weeks with moderate light, warmth, and moisture. From that point, it will generally take around 50-60 days for the plant to reach maturity. It also needs approximately two to four inches of space from the next plant to thrive. You can take several harvests of coriander from this point. Either harvesting the entire plant (and killing it) or snipping a third of its foliage off and allowing it to grow as cut and come again.
When you plant supermarket coriander, keep this in mind. Coriander is also a cool-season plant and prefers growing in warm spring or autumn weather. If left growing in direct hot sunlight, coriander will bolt. That means it decides that it’s time to send up a tall flower spike, produce small white flowers, and then go to seed. Coriander seeds can go on to create a new generation of coriander plants in the month or so that follows, or you could save them to use as a spice. After coriander produces seeds, the plant will die. It’s completed its life cycle.
Why do Supermarket Herb Plants die?
Starting coriander from seed allows you to make all the right decisions for your plant. You can choose to grow a variety such as Calypso or Slow Bolt to stop premature bolting. That helps you to grow coriander, even in summer. You can also grow the plants the correct distance apart or have a self-seeding coriander patch to keep the harvests going through spring, summer, and early autumn.
While you can plant supermarket coriander, a closer examination of the “plant” will reveal a dirty little secret. In a typical pot, there are about a dozen small plants! While you initially thought it looked healthy, you then realize that all of those tiny plants are vying for space, water, and nutrients. They’re pot-bound, stressed out, and all will die pretty quickly unless you give them what they need.
Other supermarket herb plants are the same. Each parsley plant can grow over a foot in diameter, yet there are usually half a dozen plants in each tiny pot. Thyme is a little challenging since, like coriander, there are loads of small plants growing in a small pot. Basil is another one! I have another piece sharing how you can save a supermarket basil plant and grow dozens of big healthy plants from just one pot. Mint is easily grown in a new pot as are chives and rosemary. Sage from the grocery store is also easy to keep alive.
Can you Plant Supermarket Coriander?
Though supermarket coriander (cilantro) is cramped and stressed in its pot, you can plant it to extend its life. The best way is to re-pot it in a larger pot with fresh potting mix. After that, you’ll need to grow it at around room temperature or slightly warmer, ideally. Remember, hot temperatures and sun will speed up the chance of it bolting.
Supermarket coriander is grown in large commercial greenhouses with precise controls on humidity, moisture, and light levels. The pots are then shipped to the grocery store where the plants look good but begin to suffer from day one. They are not used to living anywhere but in a consistently warm environment, so they will probably fail to thrive if you plant them outside. So while you can plant supermarket coriander outside, it won’t grow as well as if you kept them inside or in a warm greenhouse or conservatory.
How to Keep Supermarket Coriander Alive
If you’ve re-potted supermarket coriander into a larger pot with fresh potting mix, you’re on an excellent path to keeping it alive. The plants, especially on the outer edges, will have more space to spread their roots. The new potting mix can also hold more water and nutrients, which you need for healthy herbs.
Keep it well watered, and give it a diluted plant feed suitable for leafy green vegetables once a week. At the point of planting, make sure to remove a third of all the upper foliage. That will give the plants more stability and reduce their losing moisture due to transpiration. You can harvest a third of the foliage each week until the plant shows signs of bolting.
Regardless of how you tend it, your supermarket coriander will only live for about a month before it begins to die or bolt. If you want a continuous supply of fresh coriander leaves, you’ll need to buy a new plant and repeat the process every month. Alternatively, buy a packet of seeds and grow your own! It’s very simple and can be even cheaper than re-potting supermarket plants.
Growing Coriander from the Supermarket
- Pair of scissors
- Watering can
- 1 pot Supermarket coriander (cilantro)
- 1 Plant pot 2-3" larger in diameter than herb pot
- 4 cups Organic potting mix Peat-free and suitable for vegetables
- Remove the plastic sleeve from the potted herb plant. The coriander stems will flop out in every which way now that the support is gone.
- Using scissors, cut a third of the growth from the top. Use this fresh coriander leaf right away, or store it for later. You can refrigerate them, but the best way to keep coriander leaves fresh is to place the stems in a small glass filled shallowly with water. Storing them like a flower bouquet can keep the leaves fresh for a week.
- You’ll see a lot clearer now that many young plants are growing in the pot. Carefully slide the roots out, and you’ll see another issue. There will likely be a mass of roots around the sides and the bottom. Coriander from the supermarket is often pot-bound.
- Many supermarket herbs can be divided at this point into smaller clumps, and it makes sense if the plant has a long lifespan. Coriander does not, and dividing can stress the plant out even more, particularly if it’s very root-bound. The best way to re-pot supermarket coriander is to place it into a larger pot with fresh compost all around the sides and the bottom.
- Transplant the supermarket coriander using a plant pot with drainage holes, two to three inches wider than the original. Don’t plant it any deeper than it’s currently growing, and make sure that there are 1-2 inches of fresh compost underneath the plant. Firm the potting mix in with your fingers and water it in. Re-potting the plant with new potting mix will give it a little extra space to grow and provide additional nutrients and water retention.
- Place the coriander plant in a bright place with direct sunlight, but ensure it doesn’t get too hot. The ideal climate for growing coriander/cilantro is 50-80F (10-27C). Keep the potting mix moist, and feed the plant with diluted organic plant feed suitable for vegetables once a week.
- Harvest a third of the coriander’s top growth once a week. You’ll get several harvests before the plant begins to die or bolt, at which point you can buy a new supermarket plant and start again. Coriander/cilantro is a fast growing and short-lived plant that naturally grows, seeds, and dies in six to eight weeks.
- Spent coriander plants can be composted or buried under the soil.
More Herb Growing Inspiration
Supermarket herbs are often the gateway to starting to grow herbs from seed! They show you what a plant looks like growing in a pot and you can learn how to care for them. However, herb plants can last longer and be much healthier if you start them from seed; both annuals and some perennials. You also get the choice of which varieties to grow! Here’s even more herb growing inspiration to get you started
- How to Grow Supermarket Basil
- Grow Your Own Herbs in this DIY Herb Spiral
- Healing Herbs to Grow in a Salve Garden