No. Lemon Balm is very definitely lemony in scent and taste, not remotely minty. And the shape and texture of the foliage is wrong too. Looks more like Nepeta.

how can i confirm if its catnip or not?

does it have any kind of scent? Nepeta IMO is not really minty, rather, like a weird spice, some are closer to white flowering steppe sage (Salvia nemorosa) which smells rather like cat pee to my nose.

more and detailes fotos would helb, Nepeta grows in a clump and often has silvery hair on leaves and stems

are there other perennials around? the seedlings (?) must have come from somewhere

Nepeta cataria is the only naturalized Nepeta in California. Odds are good that you have catnip.

Lemon balm smells like lemon candy - it should be easily recognizable.

IMPE, catnip has a musty smell, not necessarily unpleasant, but definitely not sweet.

Also IMPE, catnip leaves are fuzzy, soft and thin, lemon balm leaves are more smooth and stiff.

Hope this helps...

To my nose, catnip has a slight

sweetness, but not anything near the sweetness of Mentha species. It's a weaker scent, kind of like horehound. It can be confusing with so many nepeta-like species moving around, and their ability to easily hybridize. Horehound has an unmistakable scent. I give my cat pieces of what I assume to be catnip, but it doesn't seem to have the euphoria causing compounds. Catnip might be the only naturalized species to a large area, while other people's Nepeta cultivars are starting to escape their gardens and add more confusion, in that same area. All these mints are able to germinate easily at any time of the year. It would be nice to be able to use solid, morpholigical charecters to identify them, instead of using scent.

Carol, my cat has more of a reaction from the dried catnip that I buy. I should buy seeds for genuine catnip and see if they are any different? Ive read that kiwi fruit leaves have a greater effect on cats than catnip, but my cat's weren't interested in the kiwi leaves.

@Jay 6a Chicago, I had two kitties (both passed now :'-( ), they were twin boys. One was obsessed with catnip! The other hated it so much, he wouldn't even enter the room that had catnip! LOL