How to Grow Mint Indoors (3 Different Methods!)


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Mint

Indoor herb gardens have become incredibly popular over the years. Well, houseplants, in general, have become loved among millennials and Gen X-ers everywhere, but making an indoor jungle edible truly enhances the green thumb experience! One of the staple herbs to include in an herb garden is mint. Although it is one of the best and easiest herbs to grow, not everyone knows how to go about growing it indoors.

How is mint grown indoors? A few different ways exist to grow mint indoors – gardeners can choose to start from seed or a cutting, and grow in either soil or in water alone. When growing mint indoors, remember to keep the mint pruned and be mindful of pests and diseases. 

A few different options are out there when it comes to growing mint – or any plant – indoors. To start, choose to grow mint from seed or begin with a start (a young plant that has already germinated from its seed). From there, choices of soil (or no soil at all), container, placement, and lighting will directly affect the efficiency with which the mint plant grows.

The Basics of Growing Mint

Many different species of mint (belonging to the genus Mentha) exist, all of which are incredibly fast-growing, spreading plants. In total, about 20 Mentha species exist, the most popular of which are peppermint, spearmint, sweet mint, and chocolate mint. They must be given ample room to spread without becoming a hindrance to the growth of other plants, or even to themselves.

To do this, either give plants a large container in which to grow and thrive or even suspend them as a hanging plant, for their runners to cascade down out of the container.

Mint grows outward and spreads because they send out runners, which are essentially the branches of the mint that rest just above the surface of the soil and ultimately send out their own roots and become another luscious bush of mint.

Mint is a highly aromatic perennial plant that, again, can grow very quickly – even to the point of becoming very invasive. It is important to keep a close eye on mint plants and prune or harvest from it regularly. This plant can grow anywhere between20-35 inches tall and can persist for several years after it becomes established.

Starting Mint from Seed

Mint seeds should be sowed in the spring or fall, a safe distance from any windows or doors. Mint plants should be settled in a cozy corner or area of the house where it will not be too exposed to chilling winds or frost.

The best soil for sowing and growing mint should be rich in minerals and slightly acidic (between pH levels 6 and 7). Sow the seeds about 1/4 inch into the soil. Multiple seeds can be planted in one container. However, after they all germinate, check back and thin out the container to provide ample space for mint to grow.

Seedlings should be spaced about 18 to 24 inches apart. 

Propagating a Cutting of Mint

Mint Cutting

A new mint plant can also be grown from a cutting taken from an established plant or by dividing a mature plant. This method is known as propagation and is one of the easiest and most reliable methods of growing a mint collection once one mint plant is established.

Before propagating mint, make sure to check the plant from which the cutting will be taken. Ensure that no disease or pests are present that will be passed on to the new plant by observing the leaves, stems, and soil for any unusual spotting, insect presence, or fungal residue on the plant or in the soil. Once the established mint plant has passed this check, it’s time to grab some fresh cuttings to propagate.

How to Propagate Your Mint

  1. Choose the branch from which to source a new plant and cut it to be about 8cm (0.4in) in length. Remove the lowest leaves on the cutting and cut the stem just below the leaf node (the point on the stem from where the leaves begin to emerge). It is best to take cuttings from the top growth of the mint plant.
  2. Place the new cuttings in a glass of water. This glass should be located in an area of the home that is exposed to full sun with good ventilation.
  3. After a few weeks, the mint plant will have begun to grow the beginnings of a healthy root system. Once multiple main root extensions are present, the cutting is ready to be placed in soil. These two ways are recommended to introduce soil to the new root system:
    • Gradually introduce the mint cutting to the soil by slowly adding increasing amounts of soil to the glass in which it was propagated over a few days. This decreases the chance of the mint experiencing shock when transferred into the new environment from water to soil.
    • Go straight from water to soil by removing the cutting from the glass and placing it into a small container with well-draining soil (ideally mixed with compost).
  4. Set the soil and compost around the stem and roots of the plant by watering thoroughly after transplanting.
  5. Enjoy the new mint plant!

General Care Instructions for Mint

Mint plants prefer to grow in full sun but can also tolerate lesser light down to partial shade – so it should be placed in an area of the home that is in some way exposed to the sunlight through a window. Mint is an extremely hardy perennial plant and does not go down without a fight – which is why this plant can stick around for years at a time. It can even handle temperatures as low as -29˚C (-20˚F)!

Repeat after me: Mint must be pruned. When gardeners say this plant grows fast, they are not kidding. Mint can spread like wildfire, so it is important to stay on top of a regular pruning schedule. Focus on keeping the vertical branches trimmed (if that is a pleasing aesthetic) and pay special attention to any runners that sprout from the main plant.

Gardeners may fertilize mint when transplanting and in the spring with a slow-release fertilizer to keep it well-fed throughout the season.

Another task to keep in mind is that of pinching off flowers to prevent mint from going to seed too soon. Not only will this reduce the production of mint leaves, but it will also take away from the rich taste of the mint and reduce the content of essential oil.

Harvesting Your Mint

Begin harvesting mint once it reaches about 8 to 10cm (3-4in) in height. Harvest either individual leaves or whole stems at a time. If harvesting an entire stem, cut the stem at approximately 2.5cm (1in) from the soil line.

In order to dry mint leaves, it is best to harvest them just as flowers begin to bud. For fresh leaves and stems, harvest as needed. These are best kept in the refrigerator, in a small glass of water, or dry and wrapped in either a plastic or paper bag for up to a week.

In everything I did, I showed you that by this kind of hard work we must help the weak, remembering the words the Lord Jesus himself said: ‘It is more blessed to give than to receive.’

Acts 20:35

Best Companion Plants for Mint

One of the most reliable ways of keeping mint happy and healthy is by planting it along with other herbs or veggies that will enhance its growth and/or protect it from any pests that may sneak their way into a home.

Understandably, not many people are looking to grow an entire vegetable garden indoors. Realistically, many indoor herb gardens are used for harvesting only occasionally and kept small (and tame) for convenience and aesthetics. That being said, when choosing a companion plant, make sure it is not one that will become more of a burden than a benefit.

Some plants that make great neighbors for mint are species in the cabbage family, including broccoli and kale, nettles and chard. If mint is being grown to use for essential oils, the nettle is especially good in that it works to increase the oil content of many herbs.

Mint species are closely related to other herbs such as basil, sage, rosemary, marjoram, lavender, pennyroyal, and thyme. Any of these species grown together in the same container would do well, in addition to the ones previously listed. Although they may not present the same beneficial properties, their presence may ultimately be neutral in nature.

Do not plant mint with chamomile because these species will not grow well together.

Best Containers for Growing Mint Indoors

When choosing a container for a mint plant, keep in mind that this plant thrives in moist soil. Herbs are quite unlike typical houseplants with decorative foliage and very much the opposite of succulents, in that they need a regular, fresh supply of water to keep them healthy.

The first thing this indicates is that gardeners should avoid planting mint in a container that will not hold water well – yes, we’re looking at you, terracotta. Although this is a good choice for many decorative household plants, it is not good for an herb garden.

Regarding the other end of the spectrum, note that mint likes soil that is moist, but not soaking. Overwatering mint is just as damaging as underwatering it, and those mint plants that are housed in smaller containers are especially vulnerable to drowning or root rot.

The best containers for mint will be those that will not cause the root system to overheat and will easily get rid of excess water (proper drainage holes or a self-watering pot). If the container will be located near a window, avoid dark-colored containers.

For more information on good containers and how to achieve proper drainage, check out some of our other related articles.

The 9 Best Containers for Growing Vegetables

Good Drainage in Pots: DO NOT Use Rocks and Root Rot Explained

How to Choose Soil for Growing Mint

Ensure that the soil is able to drain well, but not drain so much that the water simply runs through the container without nourishing the root system. The best option is to go with a premixed potting soil. Check out how we make our own potting soil here – DIY Potting Soil and Seed Starting Mix to Save Money.

These mixes offer the best aeration to ensure strong growth of the root system. If the soil is too compact, the roots will face tremendous resistance when growing and expanding into the container.  The texture of these soil mixes also contributes to their ability to hold on to just enough water to nourish the plant without drowning it.

If the soil is either too compact or holding too much water, adjust the ratio of soil to air by adding perlite, vermiculite, or woodchips to the mixture, to help break up the medium just a bit.

Check out our article on using compost indoors for more information on fertilizing your mint plant naturally! Can Compost Be Used in Containers and Indoor House Plants?

Aquaponics

Mint Aquaponics

Another very cool, eco-conscious way of growing plants indoors is with aquaponics. This method is popular in that it serves multiple purposes at the same time: greening up the home, supplying food and herbs, and functioning as a habitat for aquatic friends. Mint is an especially good plant for aquaponics because it is so easy to grow and not too picky with nutritional requirements.

Aquaponics is defined as the integration of aquaculture (growing fish a re-circulating system) and ponos (the Greek word for growing plants with or without media, or soil). Note that this is slightly different from hydroponics. The key difference between the two is that aquaponics involves the presence of fish and other aquatic organisms, while hydroponics focuses only on plant growth.

Not only is this a fun method to grow mint indoors but it is also one of the most efficient. The fish tank pumps water for the plants, the present bacteria (associated with the fish) then convert ammonia and nitrite to nitrate, the plants absorb this nutrient-rich water, and the filtered water that has now gone through the plants is distributed into the tank, fresh and clean!

This method is also less expensive as it uses only about 10% of the soil a gardener would otherwise use in a traditional soil medium. Additionally, there is no need to purchase fertilizer since the bacteria and fish’s waste feeds the plants. It also reduces the chance of pest infestations, as there is no soil for them to hide in.

How to Set Up an Aquaponics System for Mint Plants

A wide variety of aquaponics tank designs on Amazon are out there for indoor herb gardens. They vary widely in size and shape, so the type of container used depends greatly on a gardener’s needs and preferences. One of the most important things to keep in mind when choosing an aquaponics setup is the desired location of the tank in the home.

Of course, as with mint planted in soil, a tank should be placed near a window for exposure to sunlight ranging from full sun to partial shade. However, this may not be best for fish kept in the tank. This is where a grow light comes in. Many tanks come with an attached grow light, while others do not – make sure to read up on the species you wish to inhabit your aquaponics tank to prepare.

The best fish species to keep an indoor aquaponics set up healthy and the mint happily growing are goldfish and tropical fish like suckermouth fish, cichlids, mollies, clown loaches and tetras. Pay attention to the variety of fish, though, because some can outgrow the tank pretty quickly.

With this setup especially, be extra vigilant when it comes to pruning mint regularly. Remember that mint can easily take over a small container and outgrow the system and its grow light if not handled properly!

Common Pests of Mint

Of course, whether indoors or outdoors, one of the things that needs observed regularly is potential pests that can harm mint or any other plants in an indoor herb garden. Below is a table that outlines common pest species of mint and symptoms that can be used to identify their presence.

Although it may be expected that pests are more likely to attack plants outside, these pests are so small that they can infest a mint plant in exceptionally high numbers even indoors (especially aphids and spider mites).

Pest Description Symptom Treatment
Aphid/Peach aphid (Myzus persicae) This is a small, soft-bodied insect that lives on the undersides of leaves and/or the stems of a plant. They are typically green or yellow in color but can also be pink, brown, red, or black, depending on the host plant. With a heavy infestation, leaves may become yellow and/or misshapen due to the aphids drawing the fluids out of the leaf. Necrotic spots (a fungal disease that typically follows aphids) on leaves and stunted shoots are additional symptoms of an aphid infestation. Lastly, from the aphids themselves, there will be a sticky residue called honeydew left on the leaves and stems of the plant. This is what facilitates the rise of fungal diseases like necrotic spots. If the aphid infestation is not too heavy, they can be controlled simply by pruning the affected leaves. Make sure to check any plants or cuttings you intend to transplant in order to prevent an infestation from beginning at all. “Reflective mulches” such as white or silvery plastic materials can deter aphids, as well as strong, concentrated streams of water. When infestation is particularly heavy, neem or canola oil diluted with water can take care of the problem.
Cutworms (Agrotis species) The cutworm is actually not a worm, but the larval stage of a moth. Its appearance is similar to that of a small, immature caterpillar. They come in a variety of colors depending on the species, location, and host plant. Typically 2.5-5.0cm (1-2in) in length. Stems of young transplants or seedlings may be cut at the soil line. These cuts can become infected later on. They are more active at night and hide during the daytime. If one is seen out and about, it will likely curl into a C-shape if frightened. If growing other vegetables or herbs indoors, it is very likely that the cutworm has infested these as well, as they have quite a wide range of host plants. At least two weeks before planting/transplanting or immediately after harvesting, be sure to remove all plant residue from the soil (especially if the residue is from alfalfa, beans or other legumes). Plastic or foil “collars” arranged around the bottom 3 inches of plant stems (and 1-2 inches below the soil line) can protect mint from being attacked by the cutworms. Additionally, diatomaceous earth around the base of plants is a strong defense against many pests. Wait until after dark to hand-pick the larvae from plants.
Thrips/Western flower thrips (Frankliniella occidentalis) This insect, at first glance, appears to be an elongated gnat – one that was stretched at the abdomen. They range in color from pale to yellow to dark brown, with some darker markings on their abdomen. With a heavy infestation, thrips will cause leaves to be covered in “stippling” (looks like lots of tiny polka dots) and may even appear to be silver in tint. You will also find their little black feces everywhere on the leaves. This insect requires a preventative approach, due to the fact that they transmit Tomato spotted wilt virus and can carry it for the remainder of their lives. Also, they can grow to very large numbers, and insecticide must be used at that point. Since insecticide should not be used indoors, it is best to avoid planting mint near any onions, garlic, or cereals/grains (these are highly attractant, and thrips populations will build up around these plants). Reflective mulches are useful in the early stages of the growing season.
Spider mites/Two-spotted spider mite (Tetranychus urticae) This little critter is barely visible, as it is only about 1/50in long. They can be brown, orange-red, green, greenish-yellow, or even translucent. (The final two colors are the most common.) These will just look like tiny little dots walking around on the plant. When spider mites have affected a plant, the leaves will be stippled with yellow markings and appear to be somehow bronzed. Delicate webbing may also be covering the leaves. Spot the spider mites crawling around on this webbing or on the undersides of the leaves. Unfortunately, the mites will most likely not be seen until after symptoms are noticed. Spider mites do best in dusty conditions and can severely impact water-stressed plants. This is one of the reasons many indoor gardeners wipe their plants down regularly. Spraying plants with a concentrated stream of water will help to eliminate the problem, as well as applying insecticidal soaps (but be careful and read the label! Some insecticides will actually kill the competitors and/or predators of spider mites, and ultimately worsen the problem gardeners are trying to eliminate!).

Common Diseases of Mint

Finally, it is important to know what types of diseases may befall mint when growing it indoors. Being inside makes it significantly less likely to be exposed to many different types of diseases, but it does not make the plant immune to them.

Mint rust is one of the most common diseases seen in many variations of mint. This disease particularly affects the leaves and shoots of the plant, and, if left untreated or noticed too late, it can completely defoliate the plant and leave nothing to harvest. This disease is caused by a fungus and is especially damaging to spearmint and peppermint.

One of the best defenses against both diseases and plants for herbs is to regularly look at them and keep a note of their appearance and growth. This fungal disease is true to its name in that it looks exactly like small spots of rust on the leaves of the plant.

Remember that protecting mint from insects that facilitate fungal growth is a strong preventative method, but also properly watering mint will protect it from such diseases as well. Overwatering the plant without allowing it to fully drain or dry out can also welcome the growth of fungus. Keeping mint well-pruned and well-drained can protect it from mint rust.

Summary

Mint is one of the most popular plants to grow indoors, given how easily and enthusiastically it grows. The main takeaways from this article should be

  • Keep a close eye on the growth habits of mint. Prune it regularly to keep it from overtaking its container or aquaponics setup, companion plants… and your life.
  • Mint can tolerate partial shade, but it will grow its best in full sun. Keeping mint in the sunlight from a window or somewhere in the home where it is exposed to indirect light is best.
  • Plant mint in a container that will not drain water from the soil (e.g., terracotta) and in soil that is well-draining.
  • The best defense against disease and pest infestations is prevention! Observe any cuttings, seedlings, starts or transplants before committing to them in order to avoid the spread of disease.

Once you decide which of the methods and containers is best for you, get indoors and start your dream herb garden. Mint is one of the best plants to grow both indoors and outdoors due to its many uses and amazing scent. It takes a bit of work, but once you get into a set routine, mint will stick around and supply oil and leaves for years to come!




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