Can indoor mint grow all-year round?

Question

I'm growing mint in a flowerpot, and it's been growing fine all summer but now it seems to be fading a bit, some leaves turning yellow/brown and falling off.

Is that simply because I didn't water it enough, or does it have some kind of dormant period in the fall/winter?

Here's two pics of the plant (I've removed some of the yellow leaves, they basically fell off by themselves)

Also, any tips for how to cut it / make it grow better? It's growing lots of "creeper stems" with roots, but that don't really fit in the pot so it gets a bit dense.

I grow it for tea, mainly.

Answer 1

Mint does this when constrained within a pot - its natural growth habit is to throw out long runners up to 18 inches under the ground and pop up a good distance away from the original clump, which is why its so often said its not a good idea to plant it in open ground.

Turn it out of its pot, cut the root ball into 3 sections, replant one in the same pot. If you want more, replant those in 2 other pots. It should recover and grow anew, although, if you live in the northern hemisphere, reduced hours of daylight and possible chilliness near the window means it won't grow as fast as it would in spring or summer.

One caveat though - I'm rather wondering what those black flecks beneath the leaves in the last photo are - are they just specks of potting compost or aphid infestation? If its the latter, that needs dealing with, you can either rub them off and kill them between your fingers, or use a neem spray. If the flecks are within the leaf and not removable, suggesting a fungal problem, take care with your watering regime - give it a good water when you repot, but don't keep it wet nor allow water to remain in the outer tray for longer than 30 minutes after watering.

Answer 2

Mint is frost-hardy (at least in the UK - i.e. no problem with overnight temperatures dropping to say -10C) but if it is grown in the garden, the stems usually die in winter and it grows again from the roots in spring. A relatively cold window inside your house won't kill it!

A general problem with growing "garden" plants indoors in winter is lack of light. Combined with the artificial heating, that makes the plants grow weak and straggly.

It might be better to put your mint somewhere cold enough to let it go dormant for the winter, if that is possible - even somewhere outside the house, if it is sheltered from wind and rain.

If it is developing runners, an easy way to propagate it is put some more pots around the old plant, and let the runners spread over the new pots. When the new plants start to grow, cut the runners and throw away the old plant if it is looking past its best.

Answer 3

I have had a similar situation with a peppermint plant that I planted in a container over the summer and had an aphid infestation which eventually subsided.

The plant was in ill health and the vegetative stalks dried out and died completely over the winter.

In hopes that it was just dormant, I continued watering every week or two and placed it in a sunnier spot, but from around October through January it appeared completely dead. In February, the plant started to regrow completely from the bottom runners so I chopped the taller dead stems and let it grow up from the base.