Going by I naturalist observations, Nepeta cataria is by far the most common species in Ontario with 1250 observations. There are 4 observations for Nepeta racemosa, and 55 observations giving only the genus, so the 55 that aren't ID'd to species could be any number of these 2 species, or include Nepeta camphorata, or Nepeta grandiflora. Floral, do you know any way of distinguishing between Nepeta cataria and other Nepeta species? It's confusing that they call the entire genus Catmints, when only the one species N. cataria causes feline intoxication. A lot of people think catnip and catmint are the same entity. Catnip is Nepeta cataria exclusively, and a catmint can be any of the 250-300 species of Nepeta.

I am not very familiar with Nepetas, so no, I can’t tell them apart. In a garden I’d imagine this could be a seedling of one of the named Nepeta cultivars.

Looks like catnip (N. cataria) to me. It’s very fast growing.

"It's confusing that they call the entire genus Catmints, when only the one species N. cataria causes feline intoxication."

The chemical in catnip that attracts cats is nepetalactone and it is present in nearly ALL common species of nepeta, just in much lower concentrations. So forms of ornamental garden catmints can be attractive to cats as well as catnip.

I never knew that. Thanks for th info gardengal. This makes all Nepetas even more difficult to tell apart. When I google catnip Nepeta x faassenii comes up, but it has no cataria genes in it. 2 sources say Faassen's catmint is sterile and 1 sources said it comes true from seed. It would be interesting to see a listing of all known Nepeta cultivars and which ones are sterile and which ones produce seed.

Nepeta, interesting. I have noticed plants grow at neighbors' across the road from us that had blue flowers all summer long, which I assumed was catmint, rather pretty to look at from afar. I can see that seeds could have made it to our property very easily. We never planted them, and if they had been here from the previous owners, then these plants really should have been growing sooner, not peak out of the soil mid summer and then grow like wildfire, but too late to bloom. I will pull them out and move them someplace else, but if they grow so quickly, I may not want them at all.

They are tough, trouble free and, as you say, they have ”blue flowers all summer long”. Sounds like a great free gift to me. You can clip them over after flowering to keep them neat and now you know what they look like, you can weed out any self sown seedlings you don’t want.

Sounds like a good plan. And thanks floral _uk for for warning me about tasting an unknown plant ! Foolish of me, I assumed it was lemon balm but was not 100 % sure. I must be more careful in similar situations.

FWIW, I always crush and sniff the leaves of unknown plants - no need to taste.

It really does look like catnip, which is not harmful to humans, and even makes a nice relaxing tea.

Are the leaves and stems rather soft and fuzzy?

Yes. People often omit mentioning smell when asking about plant ids. It’s a really important feature in many plants.

While the leaves do feel soft and velvety, here is really no fuzz on them, and the stems are strong and firm, not soft. The smell is quite strong and distinct, somewhat reminiscent of mint, but really not a clean mint smell. I am unfamiliar with touch or smell of catnip or catmint, have only seen it from afar, so a smell test does not give me a clue...

In the meantime I cut it back and moved it to an area where it can remain until I see any flowers...

Yes - I meant soft to the touch, not limp. Velvety is a better word. Doesn't Lemon balm have smooth leaves? I haven't grown it in a long time, but I do seem to recall that.

Catnip's scent, to my nose, has a sort of musky tone to it, and rather more like pennyroyal than regular mints.

Lemon balm has hairless but slightly crinkly leaves, green stems and an unmistakable, strong lemon smell, nothing like mint. It is a herbaceous perennial, not a sub shrub like Nepetas.

A year has gone by and I am still not any wiser as to what this plant is. Catmint had been suggested then, but I doubt this now. The one I had transplanted last year grew big, but is not blooming, although I have seen my neighbor's catmint bloom for at least the last couple of weeks. Mine has full sun, is just growing like a weed but not blooming . And it is now popping up everywhere in the old area where I first discovered this plant last year. It has a very distinct smell, a tiny bit like cat pee ? If it won't bloom soon and I can't use it like a herb, I will pull it out.