Spearmint plant - Feature Image

How to Grow Spearmint Plant in Gardens

Spearmint plant, also known as Mentha spicata is indigenous to Europe and South Asian temperate lands. It is known in many names including mackerel mint, common mint, lamb mint, and garden mint.

In modern times, spearmint plants have naturalized themselves in most temperate regions on the earth. For instance, they grow prolifically in temperate lands of South Africa, North Africa, South America, and North America

This article focuses on the spearmint plant (Mentha spicata), its description, propagation, caring, and uses.

Including Mentha viridis, Mentha crispate, and Mentha crispa, the species and subspecies of spearmint have various synonyms.

Generally, spearmint is used as a flavoring agent in herbal teas and various food items. Its aromatic oil is used as scenting liquid.

Table Of Contents

History of Spearmint Plant

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Dating back to the 1st century AD, the Bible and the works of naturalist Pliny refer to spearmint plant in various chapters. The ancient mythology scripts also confirm the usage of the spearmint plant in ancient times. By the 14th century, the usage of these herbs has become widespread, as confirmed by modern findings.

The Romans introduced these herbs in England during the 5th century. Turner (Father of British Botany) praised mint for being good to the human stomach. John Gerard’s Herbal notes (1597) recommend mint for various medical ailments, including dog bites.

The English colonists introduced these herbs in North America. During American Revolution, this herb was considered an important cash crop, particularly in Connecticut. Due to non-taxation, mint teas were popular among the public at those times (Even today). Various documented evidences confirm the above fact.

Today, this herb has naturalized itself throughout the USA. It functions as a valuable commercial crop in Idaho, Washington, and Oregon.

Description of Spearmint Plant

Spearmint plant - Description

Photo by কামরুল ইসলাম শাহীন (Wikimedia Commons) (CC BY-SA 4.0)

Spearmint plant is classified as an herbaceous perennial. It grows about 12-39 in. (30–100 cm) tall. As a defining characteristic of the mint family, the stems are usually square-shaped and have a few hairs.

The serrated margined leaves measure about 2–3 1⁄2 in (5–9 cm) long and 1⁄2–1 1⁄4 in (1.5–3 cm) wide. However, the leaf blade dimensions vary considerably from plant to plant. In fact, the name of the plant is derived from the pointed tips of the leaves.

During summer, these plants sprout out white or pink flowers in slender spikes. These flowers grow about 2.5–3 mm. The seeds of these flowers measure about 0.62–0.90 mm.

Propagation of Spearmint Plant

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Light

Normally, these plants prefer to grow under full sun. They can also thrive in partial shades. Under grow lights or on bright window sills, you can grow them effectively indoors also.

Soil

Ideally, the spearmint plant grows healthy in well-draining, rich and moist soil with a pH between 6.0 – 7.5. For potting, use an organic, rich soilless mixture. In general, spearmint can thrive in almost any soil type including clay and loamy or sandy soils.

Temperature and Humidity

Generally, these type of plants does not tolerate cold. They thrive well in USDA Zones 4a to 11.

Spearmint is propagated from seed, stem cuttings, layering, or division propagation methods.

Seed Propagation

Unlike hybrids, spearmint plants can be grown easily from seeds. After the dangers of frost are passed, you can start sowing seeds directly in your gardens. You can also start the process about two months before the last frost date in your area.

1.) At least 1/4 inches deep, sow the seeds in well-prepared soil or a good quality seed starting mixture and water well.
2.) These types of seeds grow well in consistently moist and warm (about 70°F) soils. So, maintain the soil moisture and temperature by covering the spot with a glass cloche or a plastic bag, particularly if you live in dry areas.

In about 2-3 weeks, seedlings sprout out of the ground.

Hardening off Indoor plants

If you have started sowing indoors, allow the seedlings to grow about four inches in height before hardening.

Then start the hardening process by gradually exposing them to indirect sunlight for about 7 -10 days. After that, you can transplant them outdoors.

Stem Cuttings

Start this process in the late spring. Using garden shears, Snip off the top portion of the stem just beneath a leaf node-set, from a matured spearmint plant. Then, remove the foliage and other debris from the bottom half portion of the cutting.

There are two ways to allow the cuttings to root as below:

Place the cutting in a glass of water, submerging about half of its length. Make sure to replace the water at least every alternative day
(or)
Dip the bottom end of the cutting in a powdered rooting hormone and plant it in a seed starting mix.

Either way, the roots sprout out in about a couple of weeks. Then, hardening of the cuttings for about 7-10 days by gradually exposing them to indirect sunlight. After that, you can transplant the cuttings outdoors.

Layering

Layering is one of the easiest methods of propagating this herb. You can perform layering all year round, provided the weather is frost-free ahead at least for two months.

1.) Select a branch that is long enough (at least six inches).
2.) Remove the foliage at the portion that is about to be buried underground.
3.) Keeping the branch attached to the parent, bury the trimmed portion at least 1 /2 inches deep. If needed, arrest the buried portion with a rock or other arrangement, to avoid upwelling.
4.) Usually, after 2-3 weeks, the buried portion develops roots and new shoots sprout out of the soil.
5.) Cutting off the branch from the parent, dig out the new shoots carefully.
6.) Transplant the new shoots in the garden and water well.

Rooting

Although spring and autumn are the best seasons for rooting, you can carry out this process throughout the year.

1.) With a good quality spade, dig out a mint clump.
2.) Using a garden knife, split out a six-inch-wide portion of the clump from the parent.
3.) To encourage fresh growth, trim off the stem top about an inch.
4.) Replant the parent in the dig-out spot. Transplant the newly rooted portion in a new spot.
5.) Water the plants well.

Being resilient, the spearmint plant needs just a small portion of root with a couple of stems attached, to thrive.

Caring Spearmint Plant

Spearmint plant - Growing

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Watering

Generally, the Spearmint mint needs plenty of water to grow. When the top 1/2-inch soil dries, you must water the herb mandatorily. Otherwise, it may die in dry soils.

Water at least twice a week to keep the soil moist. But be careful not to water or to cause waterlogging.

Mulching

Generally, these herbs exhibit their best flavor when grown under full sun. So, most growers grow them under direct sunlight. This dries out the soil quickly. Hence, it is advisable to add natural mulches like grass, leaves, compost Etc., to retain moisture.

In areas that have significantly fluctuating temperatures between daytime (about 80 F) and nighttime (about 60 F), these herbs exhibit enhanced flavors.

Fertilizer

Although these herbs don’t need fertilizer to grow, it is advisable to annually dress them up with well-rotted manure.

If the soil is too acidic or alkaline, amend the pH. If your soil is seriously deficient in potassium, nitrogen, or phosphorus, treat it with well-balanced NPK fertilizers.

Spread Control

These herbs tend to spread faster. There are many ways to keep them contained.

Simply pull-out spreading plants using weeders. You can also install barriers (at least a foot deep) to check the spreading effectively. To encourage bushy growth, just leave an inch or so of stems above the ground surface.

Pests and Diseases

Generally, spearmints are hardy, fast-growing plants. It can thrive to some extent in the worst conditions too. However, there are some common pests and diseases that can infect these herbs.

Pests

Two-Spotted Spider Mite

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Measuring about 3 – 4 mm, these translucent-colored pests usually live underside of the foliage. They mostly infect newly growing young seedlings. These insects thrive in hot conditions. Causing speckled discoloration on foliage, these mites leave the web behind that looks like a spider web.

You can just wash off these pests with blazing hose water. Beneficial insects like ladybugs prey on these mites. You can also treat them organically with hydrogen peroxide or garlic water.

In spite of all these treatments, if the problem persists, use plant-based insecticides like pyrethrum.

Loopers

Growing about 1–2 inches in length, these loopers (Alfalfa, Cabbage Looper) are known for their foliage-consuming capabilities. They have varying green shades. By consuming large portions of stems and foliage, they cause significant damage to the plants.

You can remove them by hand if they are fewer in numbers. Otherwise, treat them with bacillus thuringiensis.

Flea Beetles

Growing about 1.5 cm, these shiny bronze /black colored insects chew a cluster of small holes through the leaves. As a result, the leaves shrivel and die off. When you shake the plants, these insects often jump off the leaves.

Mostly, flea beetles infest young seedlings. By covering the seedlings, you can protect them from most insects including flea beetles.

You can use sticky traps to capture and remove flea beetles. Neem oil sprays keep these insects away and protect the plant from various other insects also. Diatomaceous earth treatment kills these insects.

Diseases

Powdery Mildew

Powdery mildew is a common fungal disease among plants. It spreads through soil or wind to nearby plants quickly. The affected foliage develops creamy/whitish powdery patches on its surface. It causes stunted growth in plants.

Naturally, pruning plants and facilitating airflow around the plants prevent this disease to a great extent. You can treat the affected plants with neem oil sprays or organic fungicides effectively.

Black Stem Rot

Spearmint plant - Black stem rot

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This fungus thrives and spreads faster in soggy soils and wet, cool environments. The infected stems develop dark brown or black cankers. Turning yellow, the foliage in the infected stems wither.

Generally, low draining soils and waterlogging cause this disease. Remove and dispose of the infected plant and the surrounding soil. To avoid further spreading of this disease, keep the space aerated and maintain the soil pH of about 5.5

Mint Rust

Mint rust is a fungal disease that infects plants in high humid, dry climates. Mostly, this fungus infests young shoots. The infected stems and foliage will develop dusty yellowish-orange pustules. As the disease progress, these pustules turn pale yellow or black.

Mostly, these pustules form along the stems and underside of leaves in the spring. These pustules break open in early summer (June, July) and spread to other plants through the wind.

Upon spotting pustules, remove and dispose of the infected plants. Otherwise, these pustules tend to break open, drop down, and contaminate the surrounding soil.

Harvesting of Spearmint Plant H2

Oil

For extracting oils, harvest the mint in summer. Due to the heat stress, these plants produce more oil in summer. For yielding the best concentration of oils, harvest them just before blooming.

Seeds

Once the plant blooms, you can collect seeds and store them for future uses.

Domestic usage

For domestic cutlery uses, you can just pluck the stems and leaves as needed all-round the year.

Preservation

Refrigerator

After packing the mint leaves in normal plastic bags, just store them in a refrigerator. This extends their shelf life up to 3-4 days.

You can also freeze them for preservation. Wash the spearmint leaves in running water thoroughly. Then chop them using good quality kitchen knives. After that, place them in ice cube trays and freeze them.

You can directly toss frozen mint in cool drinks and recipes. This enhances the flavor to a great extent.

Drying

Just hang the spearmint bunches upside down in wall rope arrangements or hooks. You can also spread them on a screen and place the arrangement in cool, dark, dry spaces. These processes dry the herb naturally in a few days.

For quick results, just place the leaves in a food dehydrator or oven and heat them at low temperatures. They turn crisp typically in a few minutes.

Medical Uses of Spearmint Plant

The leaves and oil of the spearmint plant are used in medicine. It is used to treat digestive disorders including gallstones, nausea, indigestion, gallbladder swelling (inflammation), and diarrhea.

It is also used to cure various other diseases including headaches, toothaches, sore throat, colds, and cancer.

Word of Caution

Photo by Hannes Grobe (Wikimedia Commons) (CC BY 3.0)

Excessive intake of spearmint tea may damage the uterus. It can also aggravate kidney and liver disorders. Consult medical experts before consumption.

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