If you have access to green spaces (in your yard or somewhere you can gather ethically) you can also practice feeling the energies of the plants you encounter. I do this by grounding myself and casting a circle, and then closing my eyes and focusing on the energy of the plant in my mind's eye. Notice the energy or light radiating from the plant, and you can often see a color. Allow the plant to communicate with you. And ask for permission before harvesting a small amount for your spell. And then make sure to energize it and thank it when you are done.
That's a really cool concept, and I don't see any reason why it wouldn't work, but if I were you, I would consider leaving out the annuals (chamomile, calendula, and dill) and replacing them with other perennials like mugwort, mullein, and comfrey? A lot depends on your climate, but in my area (Zone 8a) a lot of those herbs stay green year round and even grow through the winter, and would just crowd out the annuals over time. Also, just keep your mint in a pot, it will just try to take over the whole space.
But a small pond at the bottom with Calamus would be incredible!
There are so many ways of dealing with this, and maybe you could try a few, or allow your intuition to guide you to the right spell, but my first thought was to cast a protective spell on yourself, to absorb the negative energy of your landlord.
If you're just starting out gardening, my best advice is to start slow(ish). It's easy to let your list of plants become so long that it is overwhelming. Choose a few (between 3-8) plants that are useful, or that you are drawn to. Spend a little time reading about their care requirements, and then plant them and take care of them.
My first herb garden was all in ceramic pots on my back patio.
A few herbs you might consider starting with:
Lemon Balm (spreads like mint!)
Rue (not edible)
Comfrey (not edible)
Most of those are edible, so they can do double duty in the kitchen.