There's a thread on this same topic just down the page a bit, with 30 responses.

Is it perilla frutiscens?

As DTeager already mentioned, this should help: [recent thread on minis[(https://www.houzz.com/discussions/i-fell-in-love-with-minis-but-how-best-to-overwinter-them-dsvw-vd~4866804?n=30)

lindalana, that plants looks quite pretty! Is it a perennial, or do you have to collect seeds and grow from seed each year?

linnea56, would love to see a pic of your combo if you could post one/some :)

It is annual thar reseeds quite well

lindalana, thanks for giving me a lead on what the mystery plant is. I thought at first it didn't look enough like perilla, being very frilly: then saw there is a cultivar perilla frutiscens crispa. I have yet to eat any, I just like the way it looks. I've had a colony in the front yard for a while. When it crops up I could transplant it, but so far I like where it has shown up. How one ended up in the pot with the hosta is unknown: because that was in the back yard and the soil came from a bag. I think Peanut just wanted edible company.

http://www.specialplants.net/shop/seeds/perilla_frutescens_var._crispa/

Ah, true love.

-Babka

never did get this picture posted. Here it is!

Perilla and Peanut, above. Photo from mid September.

The perilla has since gone to seed and disappeared. Peanut is declining but still there. Have not yet housed it for the winter.

I had forgotten about the sweet potato cutting I stuck there. So now it's peanuts, sweet potato, and thai / japanese sauce. Nice light dinner in the garden!

In Japan it’s called shiso, I’ve made pesto with it before. As lindalanasaid,it’s a prolific reseeder. The honey bees loved it.

In southwestern Ontario the climate is probably similar, I put the pot in the unheated garage, check it every couple of weeks so that it doesn't dry out and water if necessary. I do this with my minis and it seems to work, And with your plastic pot it won't dry out as fast as pottery. Someone suggested putting ice cubes on overwinterimh pots, and I haven't tried it but water seems to work for me. Just so it doesn't dry out. Good luck. P.S. Mine are still outdoors... No frost yet here...not even on the two week forecast!.