Herb · Lamiaceae
Spearmint
Mentha spicata
Keep it watered and give it its own container, and spearmint just keeps the fresh leaves coming.
Full sun
Every 2–4 days
59–77°F · 15–25°C
80–90 days
Overview
Spearmint is the mint you already know, the one behind mint sauce, a pot of tea, and that cool sprig in a summer drink. It's part of the mint family and lives as a hardy perennial, so it dies back over winter and bounces right back each spring with fresh, toothed leaves and a sweet, clean smell. Want an herb that's hard to kill? This is about as easy as they come, and that's both the fun and the catch.
Here's the one thing to know. Spearmint spreads by underground runners that creep sideways and root wherever they land, so a single plant can fill a bed before you know it. That's why most people grow it in a sunken pot, a bed all its own, or behind a deep root barrier. Give it that one boundary and honestly, it barely asks for anything else.
The trick to great spearmint? Keep cutting it. Pinch the tips a lot and you'll get a low, bushy plant loaded with tender leaves, but let it flower and the stems stretch out while the flavor drops off. So pick early and pick often, and it'll keep giving right up until the first hard frost.
Care
The short version: full sun or a bit of shade, soil kept evenly moist and never bone dry, and a spot where the runners can't wander off. Pinch the tips a lot and it stays nice and bushy.
Light
Spearmint loves full sun, which keeps it nice and compact and packs the leaves with the oils that give them their flavor. That said, it's totally happy in partial shade too, which comes in handy in hot spots where a little afternoon cover keeps it from wilting.
Water
Keep that soil evenly moist and don't let it dry out, because spearmint gets sulky the second it's thirsty. Watering every 2 to 4 days usually does it, though you'll want to do it more often in a heat wave or in a pot, since containers dry out fast.
Soil
Give it rich, loamy soil with lots of organic matter, the kind that holds moisture without turning into mud. A pH somewhere around 6.0 to 7.0 is perfect, basically neutral, so most garden soil already fits the bill.
Temperature
Spearmint's happiest between 59°F and 77°F (15°C to 25°C) and really gets going in that mild range. When winter rolls in, it just dies back to the roots and pops up again come spring, so a cold snap is no big deal.
Humidity
Regular indoor air around 40% to 70% keeps the leaves looking good and full. Really dry air can bring on spider mites, though, so keeping the roots moist and giving it the odd misting helps a lot during a hot, dry stretch.
Feeding
One feeding of balanced fertilizer or compost in spring is really all it needs to cruise through the season. Just go easy on the nitrogen, because too much gives you soft, floppy growth and thins out the oils that make the leaves taste like anything.
Pruning
Pinch and harvest the tips often to keep it bushy instead of leggy, and cut it back hard after it flowers to bring on fresh growth. Snip off the flower spikes as soon as they show up, because once a stem blooms, its leaves kind of lose their zing.
Repotting
In a pot, repot it every 1 to 2 years, or sooner if it goes rootbound, and it's a great time to split the clump while you're at it. How do you know it's time? Roots circling the pot edge, soil that dries out almost instantly, and leaves that are getting smaller.
Size & spacing
Spearmint gets about 12 to 24 inches (30 to 60 cm) tall, but it spreads even wider, reaching 24 to 35 inches (60 to 90 cm) across as those runners travel. So give it some elbow room, or better yet a container, so it doesn't crowd out whatever's growing next to it.
When to plant
Spearmint's a hardy perennial that handles the cold just fine across zones 5 through 9. Put your plants out in spring once the hard frost is gone, pick leaves all season long, and pinch off those flower spikes in summer so the leaves keep tasting sweet.
Northern hemisphere
Southern hemisphere
Typical months for a temperate climate: start earlier in warm zones, later where spring frosts linger.
- Sow: Late winter to early spring (though division/cuttings are more reliable than seed)
- Plant: Spring, after danger of hard frost
- Harvest: Harvest leaves throughout the growing season; pinch off flower spikes in summer to preserve leaf quality
Hardiness
USDA hardiness zones: 5–9
Temperature: down to -29°C
Troubleshooting
Spearmint's pretty tough, so there isn't much that goes wrong, mostly a leaf disease, a couple of hot-weather bugs, and its habit of spreading too far. Find your symptom below and jump on it early, while it's still an easy fix.
Rusty orange spots showing up under the leaves
That's mint rust, a fungus that turns up when the leaves stay damp and packed together. Pick off the spotted leaves and toss them in the bin instead of the compost, then thin things out so the air can move. And if a clump's really covered? Cut it right down to the ground and it'll come back clean.
Fix:
- Remove and destroy infected foliage (do not compost)
- Improve air circulation by thinning crowded growth
- Avoid overhead watering to keep foliage dry
- Cut back severely affected plants to ground level
Speckled, washed-out leaves with fine webbing
You've got spider mites, which show up when the air's hot and dry and suck the leaves until they look dusty and pale. Hit them with a strong blast of water, then keep the soil moist and the humidity up so they don't want to stick around. If it's a bad one, insecticidal soap will sort it out.
Fix:
- Rinse foliage with a strong spray of water
- Raise humidity and keep soil moist
- Apply insecticidal soap if severe
Mint creeping out and taking over the bed
That's just spearmint doing its thing, sending underground runners out that pop up as new shoots way off from the parent, and left alone it'll take the whole bed. Easiest fix? Grow it in a buried bottomless pot or a bed of its own, or sink a root barrier at least 30 cm deep. If a runner sneaks out, just dig it up before it roots.
Fix:
- Grow in a buried bottomless container or dedicated bed
- Sink physical root barriers 30+ cm deep
- Dig out and remove escaped runners promptly
Weak growth and smaller leaves from a matted clump
An older clump ends up crammed with tangled roots and runners until the middle poops out and the leaves shrink. Just lift it, split off the good outer bits, replant those in fresh soil, and chuck the woody center. Do that every two to three years and it'll keep cropping like new.
Fix:
- Divide the clump and replant healthy sections
- Refresh soil and discard the woody center
Toxicity
Good news first: spearmint's a kitchen herb people eat all the time, so there's nothing to worry about on your plate. The thing to watch is its essential oils, which can give cats, dogs, and horses a mild stomach upset if they eat a lot, so keep the grazers away from a whole plant.
Toxic to
Cats · Dogs · Horses · Rabbits · Livestock · Birds
Safe for
People
Cats Mild
A cat that nibbles a leaf or two is usually fine, but a big mouthful of the oily leaves can leave it drooling, throwing up, and dealing with loose stools.
Dogs Mild
If a dog chews its way through a bunch of leaves, it might get an upset stomach with a bit of vomiting and diarrhea that clears up on its own.
Horses Mild
A horse that grazes a big helping can end up with a mild bellyache and soft droppings, thanks to those concentrated oils.
Rabbits Caution
A few leaves here and there are fine for a rabbit, but the strong oils mean it really shouldn't make a whole meal of it.
Livestock Caution
Goats, sheep, and cattle don't usually go for mint, and a quick browse won't hurt, though a belly full of it can loosen their digestion.
Birds Caution
Most birds steer clear of the strong-smelling leaves, so just offer a tiny bit, since the oils are stronger than a little body wants.
People Safe
For people it's totally fine, a kitchen herb folks have eaten for ages in teas, sauces, and salads without a second thought at normal cooking amounts.
Normal culinary amounts of spearmint leaf used in food are not a concern; the risk relates to ingestion of large quantities of the plant or concentrated essential oils.
Helpline numbers
United States
ASPCA Animal Poison Control: (888) 426-4435 (fee applies)
United Kingdom
Animal PoisonLine: 01202 509000 (fee applies)
Australia
Animal Poisons Helpline: 1300 869 738
Varieties
Most spearmint you'll come across is just the plain species, but a couple of named types are worth hunting down if you want more flavor or a fancier leaf.
Mentha spicata 'Kentucky Colonel'
Its big, crinkled leaves pack a seriously strong spearmint flavor, which is why it's the go-to for juleps and for cooking.
Mentha spicata var. crispa (Curly mint)
Those tightly ruffled, curled leaf edges give it a fun, frilly look while it still smells like clean, classic spearmint.
How to propagate
Making more spearmint couldn't be much easier, and most folks skip seed entirely and just split a clump or root a cutting instead.
DivisionEasy
Spring or autumn · 2 to 4 weeks
Splitting a clump is honestly the surest way to get more spearmint. In spring or autumn, just lift an established plant and pull it apart into sections that each have a bit of runner with its own roots and shoots, then pop them back in the ground. Each one settles in and takes hold in about 2 to 4 weeks.
Stem cuttingsEasy
Spring through summer · 1 to 2 weeks
Spearmint roots so easily that a cutting barely needs any help. Anytime from spring through summer, snip off a healthy stem tip and either stand it in a glass of water or push it into moist soil, and you'll see roots in 1 to 2 weeks before you move it on.
Myths
Mint's harmless in the garden since it's just a little herb.
Don't let its size fool you. Spearmint spreads underground and can swallow a whole bed in a season or two, so it's smarter to plant it in a buried pot or behind a root barrier than to just stick it loose in the ground.