Nyc - Fired Gardener Running Business Out Of Back Yard / Squatter Situation?

Location: NYC. I am a tenant who rents a house from an elderly 85 year old landlord. The landlord spends most of the year out of the city, and we have a great friendly relationship. Two years ago, the landlord made a handshake agreement with a gardener, where the gardener agreed to mow our large back yard and trim the trees and in exchange, she would "keep a few personal plants in the back yard."

Well "a few plants" turned into hundreds, and then she built multiple shelving units to store even more back there. The truth came out that she ran a plant business selling these plants to her clients, and she was just using our yard as storage space. She spends all day back in the yard caring for her plants, and bringing strangers in and out to haul them to a truck to deliver them. We were very patient at first as we thought the landlord knew what she was up to, despite her having sort of a nasty attitude(we just tried to ignore her/stay out of her way/avoid the yard even though it's in our lease to use).

She then stopped taking care of the lawn and trees, and we wound up purchasing our own lawn mower to do it ourselves. Our dogs then got fleas from one of her plants. One of her assistants was caught stealing her materials from the yard(cops were called by her). The yard became absolutely flooded with mosquitos. She then began to store "junk" in the yard-- broken bicycles, chalk boards, boxes of paperwork, claiming they are for her business (?). We got very frustrated and dreaded having her around.

Our one rule to her was to keep the back patio clear, but it filled with junk and she straight up refused to clear it out. The Landlord then came to visit the home and got mad when he saw how many plants there actually were, realizing she was using it as some sort of storage space, and very mad that the patio was blocked / that she was using his water on the plants.

This led to an in-person confrontation back in November 2025 where all we were asking was to clear out the patio, and she got in our elderly landlords face (and her gardening assistants did as well) saying that she was a tenant too, that her things have been here for longer than 30 days so she is a tenant. She also said she didn't have to listen to anything we as the renters said, knowing our landlord is a bit of a pushover & not here for most of the year. But it was after this happened and the landlord witnessed how rotten she was that he agreed that she had to leave--

We helped him write an official letter stating: You are no longer to perform gardening services here, you are to remove your items from my property by Jan 1st, you are not allowed on my property unless you are moving your things out, and if they are not removed by Jan 1 they will be considered abandoned property.

Well Jan 1 came and went, nothing got moved out besides one shelf. We didn't see or hear from her. We installed cameras everywhere. Eventually she began coming around to peak into the back yard when my husband's car was gone. So we put up a rope that says "NO TRESPASSING ".

Today was the first nice day of the year, and she sauntered into the back yard and began doing work on her plants. My husband was already back there and said, "you are not allowed to be here", and an argument ensued. She claimed she is still a tenant, but also claimed she is going to "Be out by the end of the month/out by the first". After walking away, we overheard her on the cameras talking shit about us on the phone with someone saying that "we never use the back yard anyway".

She then called the landlord and threatened to "drag this out" if we continue to confront her or be in the yard to "antagonize" her while she's there, and the landlord called us in tears begging us to stay out of her way, fearful of the legal action for all the "unpaid services" she's done over the years. After he calmed down, he called again and said let's just pray she's out by the first, but I don't know if I believe she'll actually be gone.

Does anyone know what we can do in this situation? Can she claim to be a tenant without a lease, without sleeping here, without mail, without any contract or written work at all? No money between her or my landlord has ever exchanged for any services at all or for "rent", it was a handshake/verbal deal. I don't feel safe around her or with her men coming into the yard to work, and i don't know if calling the cops will do anything if she claims to be a "tenant". We do NOT want to move, mostly because our house is incredible, our rent is insanely low for the area and we'll never find a place like this again. Thank you in advance for any advice.