Growing Mint Without Losing the Garden: Containment, Varieties and Rust
Seed often won't give you the flavour you wanted, and a sunken pot with its rim above the soil keeps the runners where you put them.
One clump of mint can keep a household in tea, sauces and summer drinks for years, and the same vigour that makes it so productive lets it wander into every bed nearby.
Two facts explain most of what gardeners run into. Mints cross with each other so readily that seed often won’t give you the flavour on the label, and they travel underground, so how you plant them decides where they end up. A pot sunk into the bed, with its rim left above the soil, holds them well.
How many kinds of mint are there?
More than anyone agrees on, because mints blur into each other. The Royal Horticultural Society estimates 25 species plus numerous hybrids, while a 2020 peer-reviewed review cites a stricter count of 18, and explains that “Wild species of mint hybridize readily”, so small differences have ended up ranked as separate species. Citing earlier phylogenetic studies, the same review says peppermint likely arose from spearmint crossing with water mint.
In the garden, that variety shows up as spearmint, apple mint, lime mint, chocolate mint and many more. If you only have room for one, the RHS points to spearmint for its many culinary uses, and NC State Extension calls it “one of the best mints for flavor”, used in teas and other drinks.
Can you grow mint from seed?
Yes, but you can’t choose the flavour. The RHS gives a sowing method (seed on the surface, kept at around 20 °C, germinating in about two weeks), so seed does work. Utah State University’s peer-reviewed extension fact sheet explains the catch: because mints readily hybridise, “plants grown from seed often fail to be true to type”. It suggests buying established plants, taking cuttings or dividing a clump you already like.
Peppermint is the extreme case. NC State notes that it blooms in summer and “rarely set seed”, and recommends propagating it by division or stem cuttings. Our tea garden guide covers peppermint pot sizes.
How does mint spread, and what actually holds it?
Mint moves two ways. NC State says spearmint’s square stems “can root wherever they touch the ground” and that it also spreads by rhizomes, underground stems that send up new shoots. Soil barriers, it adds, can restrain that spread.
For a bed, the RHS suggests a bottomless container or a pot with large drainage holes, sunk into the soil with the rim left “slightly above the surface to prevent shoots rooting over the top”. Utah State gives the dimensions: a buried container reaching 3 to 4 inches above the soil and 10 to 15 inches below it, which we’ve converted to roughly 8 to 10 cm above and 25 to 38 cm below. Check the rim each season and snip any stem draping over it.
If mint has already taken over a bed
Clearing it takes patience, and digging works best. The RHS warns that mint “can re-grow from small pieces left in the ground”, so dig out shoots as soon as they appear, taking as much rhizome as you can.
In a 2024 answer to a gardener, a Michigan State University Extension expert quoted Penn State advice that sets out the full job:
- Rescue other plants first. Lift any you want to keep and remove “every piece of mint stem and rhizome” from their root balls.
- Dig deeply, shaking the mint roots from each spadeful. Don’t till, since chopped roots only produce more plants.
- Wait and repeat. Leave the area a few weeks and pull new shoots as they come.
- Or smother it. Overlapping cardboard under thick mulch, with no gaps, takes a full season, and digging first works best of all.
Once the bed is clear, replant a healthy piece into a sunken pot so the next clump stays put.
Orange spots under the leaves? That’s probably mint rust
Mint rust is a common disease of garden mint, caused by the fungus Puccinia menthae. The RHS describes pale, distorted shoots in spring, then dusty orange pustules on stems and leaves, followed by yellow or black ones. Badly affected plants may lose leaves.
Removal is the main tool. Take out affected plants promptly, before black resting spores form and contaminate the soil, and remove infected rhizomes too, then dig out any uninfected stems and replant them elsewhere to start a fresh colony. Utah State adds the preventive side: avoid wet leaves overnight, water before midday, and don’t overwater or overfeed, since both promote rust. In the UK, the RHS notes, no fungicide that works on mint rust is available for culinary herbs, so removal and careful watering are the main tools for home growers there.
How do you refresh an old clump?
Divide it every few years. The RHS method is to cut the rootball into smaller sections in spring or autumn, discard “any old dead parts in the centre”, then pot up the smaller clumps or replant one back into the same pot. That stops plants getting too cramped and encourages fresh, healthy growth.
Cutting back keeps it lively between divisions. After flowering, the RHS suggests cutting the whole plant to about 5 cm for a flush of tender leaves. Utah State goes further, noting that leaf oil content drops once mint blooms and suggesting a cut to within about 2.5 cm (an inch) two or three times a season. The timing differs, but both land in the same place, and in Utah State’s words, “It is very difficult to over-prune a mint plant.”
A small mint for shade, and a native one
Most mints like sun to part shade. Corsican mint (Mentha requienii) is the exception worth knowing, and the RHS lists it as a peppermint-scented, mat-forming plant up to 10 cm tall for partial to full shade and moist but well-drained soil. Australia also has its own native mints, including Mentha australis, which the 2020 review records near watercourses and damp gullies across Australia outside Western Australia, and in Tasmania.
One mint to keep out of the teapot
Pennyroyal (Mentha pulegium) is a true mint, and the RHS notes it is listed as “harmful if eaten” by the UK’s Horticultural Trades Association. The US National Capital Poison Center explains that its oil contains pulegone, which is highly toxic, particularly to the liver, and that infants have been severely sickened by teas made with pennyroyal thought to be mint. Buy culinary mints by their botanical name from a reputable supplier, as the RHS suggests.
What this means for you
- Start from a plant you’ve tasted, or a rooted piece of one, if you want a particular flavour.
- Sink it in a pot with the rim a few centimetres above the soil and 25 cm or more of it below.
- Clearing a bed? Dig deeply, remove every rhizome you find, and keep pulling new shoots for a few weeks.
- Watch for orange spots in spring, and remove rusty plants and rhizomes early.
- Divide every few years, throwing out the dead centre.
Which mint has lasted longest in your garden, and has it stayed in its pot? Hit reply and tell us.
How we made this: AI tools helped us research and draft this post. We checked every figure, quote and link against its original source before publishing. Figures are as of 8 November 2026.
Grown with intention by Dynamic Nexus Garden.