Thank you. I wasn't sure if you meant me to take it to mean that the catnip won't send out runners, it not being a true mint.

This has me puzzled now about my spearmint. Even when it was gigantic (back when I had it in a large self watering container with other herbs and I found its roots 'everywhere' when I went to transplant them all), I definitely didn't see any runners.

Even though it seems to be doing quite well in it's new pot, I have noticed that the leaves on it are only about 1/4 inch to a 1/2 inch in length, while those of the chocolate mint are about 1/2 inch to an inch. I wonder if this is somehow related to why I'm not seeing any. Hmmm...

Oh, well...I'll keep my eye out for them. It isn't as though the pot I already have doesn't provide me with more than enough spearmint, so I don't really need to be propagating it. Now the chocolate mint is another story. It seems almost anyone I casually mention 'this' plant to asks me for a cutting. LOL

Mint is considered an invasive plant. That means mintwill eventually take over an area, when planted in the ground. Invasive plants are hard to get rid of once they become established in a garden. It is good that you have your mints in pots.

Yarrow is also an invasive plant/herb. The smallest bit of root left in the soil, upon removing a plant, will produce a new plant.

I think I'm confused now. I know that mints have lots and lots of roots (I've seen them when I transplanted them). But I thought the means by which they 'took over' was via the runners. So tell me if I understand this correctly. If you were to cut off a mint plant at the soil line, that plant would come back - in the exact same spot - because the roots are still there, right? But if it shows up on the other side of the driveway, it would have to be because it sent out runners underneath (rather than roots), right?

And if I really wanted to propagate my runnerless spearmint, could I move it to another pot, leaving some root material behind, and have a reasonably good chance that it would grow into another plant (assuming that I water it and expose it to sunlight)?

The roots spread far and wide and deep. So do the runners. So do the seeds, but it's the runners which seek out the light, so they're likely to go further than the roots (but not quite as far as the wind-blown seeds). Runners can be above ground, or below ground. As long as the roots are alive and reasonably healthy, the plant will regenerate, grow and spread.

The pic at the link below shows how the runners form roots and frequent at regular intervals. Any piece of runner with roots on it will grow. Roots on their own may or may not grow, but it's unlikely - depends if there's a stem which will form leaves growing from them, in which case it will.

If you had runners like the ones in the pic, you could remove the stems with the leaves on, and a plant would grow from each runner - but most people leave stems on when they look like that, just to give the plant a head start. You could actually get 4 plants from the centre starter (possibly 5 if you count the tiny roots at the top of the picture).

Here is a link that might be useful: mint runners

Thanks! That explanation really helped my understanding, particularly the comment on how the middle photo in the link would create several plants, rather than just one.

Mint is like the Spider Plant. It propogates 3 ways. It has Flowers that drop Seeds like other plants. It has Roots that spread & it has Runners. Runners are the Roots that grow from Stems of Mint touching water or soil. Strawberries spread with Runners too. It is advised not to plant the pot Mint is in, in the ground. The Roots can find their way out through cracks & drainage holes & Runners can just flow over the edge at the top. If you do want to place it in the garden area, put the pot up on bricks, so you can cut the Roots when they appear below. You can easily cut off the Runners if they start to droop over the edge. It is advisable to cut off the Flowers before they go to Seed.

It is so interesting which plants are invasive where. If I don't actively water mint during the summer, it dies in the ground every single summer. It does like to grow in the spring, fall, and warmer time of winter here.

There is also a mint here in CA that is aggressive, but isn't considered "invasive" because it's native. Still spreads the same way tho.

Wild mint / Field mint: https://www.calflora.org/cgi-bin/species_query.cgi?where-calrecnum=5413

I personally love mints. Even though they're aggressive garden thugs.

Catnip and mint share many family characteristics. Eventhough catnip is not mint.