In my experience, every generic gardening article online always says, “Mint is incredibly easy to grow”..
While this is true (mint can be really hardy), it sort of misses the real challenge of growing mint, which isn’t keeping it alive but keeping is high yielding, full of flavour, yet strictly contained to a pot.
When I first started gardening, I made the mistake of planting some spearmint directly into a raised bed right next to my heirloom tomatoes. As you can imagine, by mid-summer, my tomatoes were struggling to compete with the mint as the mint had sent subterranean runners around the raised bed and even under the sleepers into the gravel path 3 feet away.
I personally found that digging it all up was quite the challenge!
Whether you’re growing your mint indoors on a sunny south-facing window, outdoors on a patio, or even managing it in the ground (not recommended as it spreads), then my guide has first-hand experience and experiments and the exact protocols you need to grow thriving mint.
The Anatomy of an Invader: Why Pots are Better
In order for us to successfully care for our mint, we have to undertsand how it moves around the garden. Mint spreads via stolons (which are also called runners). These are horizontal stems rather than roots taht run both above and below the soil surface, and every single node on the runner can start roots and grow a new mint plant.
[Leafy Shoot] [Leafy Shoot]
^ ^
======|=======================|====== Soil Line
|---[Runner/Stolon]-----|
/ \ / \
[Roots] [Roots]
My 4-Week Escape Artist Experiment
To test just how aggressive the runners can be, I decided to run a mini experiment in my garden last spring. To keep the variables the same, I just had two peppermint starter plants, but in two different environments.
- Mint Plant A: A wide, yet shallow clay bowl.
- Mint Plant B: A deeper, more narrow 12-inch traditional-shaped terracotta pot.
The results were that within just 24 days plant A runners had reached the edge of the shallow bowl and even spilt over the side and even began just hovering in the air on the lookout for more soil to drop its roots into. Plant B, however, took nearly 6 weeks to fill its container as the deeper soil meant the mint focused on building a denser, more robust central root system first.
The Takeaway: So from now on, I grow my mint in a deeper container as this forces a healthier, more resilient root system that does far better in drought conditions.
The very best Soil, Sun, and watering for your mint plants
In its natural environment, mint often grows on the banks of small streams. If you treat your mint like Mediterranean herbs such as rosemary or lavender (which much prefers sandy, dry conditions), the mint turns woody, bitter and yellow.
1. The Perfect Soil Mix for Your Mint
In terms of soil, mint likes a balance. It wants moisture-retentive soil that still has good drainage to avoid root rot.
I did a lot of experimenting with the perfect soil mix for mint, and here is my favoured composition…
- I use 70% Multi-Purpose Compost (for nutrient retention and moisture).
- I use 20% Perlite or horticultural Grit (for better drainage at the bottom of the pot).
- I use my secret ingredient, which is a bag 10% Worm Castings (you can order this online for a reasonable price) or Well-Rotted Manure, which I source from a local farm (for better yield of tasty leaves).
Since I added the worm casting to my potting mix (I started about 2 years go) or manure (both are equally good), my yield of mint leaves is much better, with larger leaves and more aroma and they taste even more potent in tea. I would just avoid adding too much manure; for example, 50% manure would contain too much nitrogen, causing the mint to grow floppy.
2. Light Requirements: The Sweet Spot
I often see advice saying mint needs full sun, however I have found that at the height of summer in scorching temperatures, full sun can scorch the leaves slightly, which harms the aromatic oils and reduces the aroma and flavour of the leaves.
This is, of course, somewhat location-dependent…if you are in the rainy Pacific Northwest or Britain, then full sun is going to be good. However, in Southern California…
- Outdoors: I would aim for dappled shade or morning sun with afternoon shade.
- Indoors: I would place my mint on a South or West-facing windowsill, but keep a close eye on the leaves, and if the stems become long, thin, and leggy, our mint is stretching for more light intensity (phototropism) and needs a brighter windowsill or perhaps even a cheap LED grow light to supplement the light.
3. The Watering Frequency
Mint leaves are expressive, which helps us know what’s going on. If your mint needs water, it can wilt dramatically in hours. As we discussed, mint grows naturally on the side of streams with nice, moist soil, so we need to keep our soil damp.
During the hottest days of summer, I find that outdoor potted mint needs watering every single day. Indoors, what I do is check the top inch of soil with my finger, and if it feels dry, I give it a really good soak until water runs out of the drainage holes in the base of the pot.
I would also pick it up to see whether the pot is heavy or not after watering, as the goal with watering is to ensure that the soil is evenly moist, and a heavy weight is a reassuring sign that the water is actually being absorbed by the compost rather than just running off the surface, which can, of course, lead to drought and wilting.
My favourite pruning hacks for How I Get 3x More Leaves
Most people harvest their mint plants by taking individual leaves off the plant as they need them, but I would recommend not doing this, as it can stress the plant, and there is a better way that I use.
To maximise your mint harvest each year, the best way is to prune strategically to force the mint into branching.
My 3-Week Pruning Experiment
I did a test where I set up a side-by-side comparison of two practically identical mint plants to find the best yielding method.
- My Method 1 (The Soft Pinch)…On Plant A, I only snipped off the very top of the cluster of tiny leaves when I harvested.
- My second method (The Hard Chop)… On Plant B, I pruned the mint plant’s stems back by around a full third, making the snip at 2 millimetres above a mature leaf node ( this is where a pair of leaves meets the main stem).
[Snip Here] ---> ======= X =======
/ \
[Leaf] [Leaf]
\ /
[Node]
My Results: The Plant A mint had produced long, single stems that eventually fell to one side under their own weight. Plant B, however, grew much better. This is because I pruned right above the leaf node and the mint plant had sent out two entirely new branches from that single node. Within around three weeks, my Plant B was three times bushier and yielded a 40% higher leaf weight (for lots more mint tea!) than Plant A.
Pro-Tip: Every 4 to 6 weeks, I recommend giving your mint a good hard chop and even if you don’t need the mint for cooking or tea making, snipping it back prevents the stems from becoming woody and signals the crown to send up fresh, sweet, tender new growth which tatses a lot better.
Troubleshooting Some of the Most Common Problems I see with Mint!
Even a plant as tough as mint faces adversity, and if your mint looks to be dying, in my experience, it’s usually down to one of three of the following culprits…
1. Mint Rust
If you have spotted small, bright orange or brown pustules on the under side of the leaf, then you are facing Mint Rust, which is a fungal disease and travels via water droplets and air currents.
- The Fix: Unfortunately, there is no cure for mint rust, but I must warn you not to put it in your compost heap but Instead, I would dig up the mint, and put it in the bin, and sterilize your pot with a 10% bleach solution before you use it again. The best way I have been told to prevent this is by watering the soil directly, never wetting the foliage.
2. Woody, Tasteless Stems
If your mint is now more than a year old and the leaves are getting smaller, tougher, and losing their flavor, your mint plant is likely root-bound, which is where the roots have filled the pot, and exhausted all the available nutrients from the soil.
- The Fix: Slide the mint out of its pot and take a sharp spade and literally slice the root ball cleanly into quarters. I would keep one quarter, replant it into fresh potting mix, and discard or gift the rest. Whenever I have done this, it bounces back with immense vigour within two weeks.
3. Sticky Residue or Fine Webbing (Pests)
Indoors, a lack of predatory insects such as ladybirds means pests like Aphids (which leave a sticky honeydew behind) or even Spider Mites (which spin tiny webs) can be a problem.
- The Fix: I find the best way to deal with this issue is to take the pot into your garden and use a hose to wash the foliage in order to dislodge the pests and leave it to dry in the sun. You can also use organic neem oil (which is a safe organic way of getting rid of pests on your food) and concentrate on the underside of your leaves.
Final Thoughts…The One Rule to Remember
My biggest takeaway from this article should be that mint is hardy, and you should prune it back to get the most out of it. Always avoid planting it in the soil (pots are always best), give it lots of water, and you can have leaves for many years!