How to grow Peppermint – indoors and outdoors

Peppermint (Mentha piperita) is a popular and easy to grow herb. We grow peppermint indoors every spring to give us fresh plants for our herb garden later in the season.

Peppermint is a very aromatic and strong herb. The uses are many and include both drinks and food. Given that fresh herbs at your market are expensive to buy when bought in large quantities, we recommend that you grow as much peppermint as you have room for, as you will find you use it continuously during the summer. And for a very little initial cost.

A favorite way to use peppermint for a kick in the mornings is mixed with fresh greek yoghurt and berries. Wash the peppermint leaves well, chop them roughly and mix into the yoghurt. Chill in the fridge before you add berries for a delicious addition to your cereal or on its own. 

Any leaves that are over can be added to a cup of freshly boiled water with a lemon slice and a spoon of honey for a delicious mint tea. I actually like to cool and then chill a jug of mint tea in the summer. Just add ice cubes when you’re ready to drink and adjust the amount of honey for sweetness.

Of course its uses are many. Peppermint works really well with lamb and can be used both fresh and dried. It is used in the popular mojito drink. We often combine peppermint with lemon thyme leaves in a green avocado salad, dressed with fresh lime juice and olive oil.

Peppermint tea is also excellent for helping to relieve indigestion.  It’s versatility will have you using this herb all summer long, so do grow peppermint to last all year long!

Growing peppermint from seeds indoors

Start growing your peppermint from seeds indoors in early spring. 

We plant seeds in February with the intent to transplant outdoors in April /May when ground temperature is guaranteed to exceed 12 degrees celsius (53 degrees Fahrenheit). 

In this article we will give you the step-by-step of how you can succeed in growing fantastic peppermint plants to last you right through the season.

1. Select pot and soil

We recommend that you use recyclable plastic starter pots (7 centimeters / 3 inches) to help control moisture and temperature. 

Use a 50/50 mixture of loosely structured cactus potting soil and regular potting soil.

The peppermint seeds will be sown shallow and you need a well drained soil to avoid the seeds rotting.

The richer potting soil sits in the bottom half of the pot and will provide extra nutrition when the root system of the seedlings grow stronger. 

2. Plant seeds

Plant seeds approximately 0,5 cm deep and cover lightly with soil or perlite. Shower the seeds lightly using a spray bottle or water the pot from underneath using a water bath.

Cover the pot with a transparent cover but make sure to add holes for supply of air. The seeds will germinate at a higher rate if we can keep the temperature around 20-22 degrees Celsius (70 degrees Fahrenheit). 

The seeds will germinate in 7-10 days. As the first leaves start showing we remove the transparent cover and place the pot in a light spot with an ideal temperature around 15-17 degrees Celsius (60 degrees Fahrenheit).

3. Transplanting seedling outdoors

After hardening the seedlings we transplant the seedling outdoors into a pot or our herb garden.

Fast growing peppermint will spread if you let it
Fast growing and will spread. Here planted in pot.

Always grow peppermint in a pot as the herb likes to spread and has a tendency to take over. 

If you do plant in your herb garden it is a good idea to plant the seedling in a bucket or pot without a bottom. This will allow the root system to develop while preventing the plant from sending our shooters and taking over your herb garden.

The purple flowers are beautiful but after all, we can only eat so much lamb and drink so many Mojitos. 

Whether you plant in your herb garden or a pot you need well drained soil. Peppermint thrives in a moist, well drained and nutritious soil. 

We use a mixture of standard garden or potting soil blended with equal parts of peat moss and sand or Perlite. 

Peppermint can tolerate direct sun but prefers part shade.

If you are planting several peppermint plants you should leave approximately 20 centimeters (8 inches) between the plants. Should you be even more ambitious and pant in rows leave approximately 30 centimeters (12 inches) between rows.

4. Caring for peppermint plants 

The peppermint plant is quite easy to care for when it is established. 

Water regularly and avoid dry outs. Using a liquid fertilizer every 4-6 weeks will help your peppermint plant thrive. But do not over-fertilize.  

It is also easy to grow peppermint plants from cuttings or by dividing the plant.

To divide the plant we simply extract it from the soil and divide the root system into equal parts. 

To propagate from cuttings is even easier. Simply take a cutting from the top of the plant. The cutting should be about 8-10 centimeters (4 inches). Pinch the stem just above a pair of leaves to allow the remaining plant to get bushier. 

Place the cutting in a glass of water. In a couple of weeks, you should see new fresh roots forming. Keep the water fresh by replacing it when needed.

5. Harvesting peppermint 

You can harvest leaves and fresh shoots continuously throughout the season. 

The best time to harvest is just before the herb flowers. The leaves will lose some of their characteristic punch and flavor if you allow the plant to go into bloom. 

You can harvest by the leaf as well as cut sprigs or branches. But avoid cutting back more than half the length of the branch to avoid stressing the plant.

6. Preserving peppermint

You can store unused peppermint leaves in your fridge for a few days. Put the leaves in a ziplock bag with a sheet of kitchen paper. Use within 2-3 days.

Freezing whole leaves will give you access to fresh peppermint leaves year-round. Freezing is also the method that preserves the flavor best.

To freeze peppermint, spread the leaves on a sheet of wax on a tray. Place uncovered into your freezer draw. Remove after 24 hours and place the frozen leaves into a plastic ziplock bag. Squeeze as much air out of the bag as possible before sealing. Place the bag into the freezer, and use it within 6 months. 

Most people find drying mint plants to be a bit trickier. You need a cool, dark, and airy environment and it can take anything from days to weeks to dry out herbs. And drying herbs does result in some loss of flavor.  

But if you’d like to try drying your peppermint, simply place the long stems of a small bunch of peppermint upside down in a paper bag. Secure the tip of the stems at the top of the bag with a clip. Do not be tempted to put too many stems into one bag.

The paper bag is breathable but keeps the peppermint leaves dust free and dry. Do not use plastic bags.

Leave the bag standing up in a cool dark place, where there is plenty of airflow and circulation. Check to see if the peppermint has dried after 14 days. The leaves should be wrinkly and dry and crumble easily.

Then you just need to remove the stem and crumble the leaves into an air-tight glass jar for use throughout the winter in your favorite dishes! 

Meet the author: Mattias is an experienced gardener spending most of his free time on his knees among herbs, plants, and garden vegetables. For the past two years, he has been sharing gardening projects and how-to tutorials on the NordicLavender website and YouTube channel.