Your best bet is to reach out to specific contacts with your questions. Start with your local nursery and landscape association for what you would need in CT. NALP is a national trade organization and my guess is they'd love to connect someone interested in the business with someone who can help. And if you're on Facebook, there's a group called Emergent: A group for growing professionals that was specifically started to help younger folks in the business. Networking is always something good to do early and often.

Also Tony Avent of Plant Delights Nursery wrote a book on starting a nursery. Much of it may not apply to your ideas, but the green biz is the green biz. There's probably enough useful info to make it worth the ten bucks or whatever it costs these days.

While I was creating a landscape and propagating many of the plants, there would be many leftovers and these would be sold on Ebay, with varying success. There is a demand for plants that are in flower and often not much interest in those that aren't. As the landscape grew to completion, I tired of the mess and bother of caring for extra plants setting around waiting to be sold. A drawback/discouragement to online sales is shipping weight. If soil is involved it can become quite expensive. If finished, flowering plants are sold, it can also be time consuming and expensive to package them properly for shipping. Hands down, the most profitable plant products I've sold are landscape groundcover/perennial root parts ... plants that can be started from pieces of roots/rhizomes or such. There is no need to ship soil with them, or package them in a highly organized, careful way. They are usually a bunch of roots crammed in a plastic bag. If you had a dense groundcover and dug up one square foot of it -- lily of the valley, for example -- there would be literally hundreds of pips in that square foot. After calculating out a plant spacing, it might turn out that the single square foot is capable of starting 100 square feet of new bed, or possibly more. Instead of a buyer who wants just one or two plants, a buyer who is landscaping and wants enough for 100 or 200 square feet or more of bed would be happy to find a bargain on Ebay where they can get that material for $50 or $60. It might only amount to a pound or two of shipping weight that doesn't need padding or careful wrapping. Last summer I had some leftover pavers so decided to widen the driveway. The plant adjacent to the drive edge was perennial peanut. Instead of throwing it away, I offered it on Ebay and ended up selling several hundred dollars worth of it. It wasn't until near the end of the summer before it was all sold and I was ready to do the project, but that worked fine with my schedule. It took me no extra care or cost to cultivate it. It was already there for the taking. By the time summer was ending, the early material I had removed was already growing back from what root pieces remained in the ground. It could have become a perpetual operation.

You will need to decide what you can do within the extreme limitations of your apartment. At the very least, you should be prepared to comply to state and federal laws regarding the shipment of plants and soil. A legitimate plant retail store will be expected to record and report sales, of course.

Are you wishing to buy finished plants from a real grower, have them shipped to your apartment so that you can resell them to online customers? Or are you interested in procuring bareroot rooted cuttings (called liners) or plugs, repotting them into small containers with a porous medium and growing them for a few months?

Of course, then you would need space, lighting, etc.

When I started my wholesale container nursery many years ago, I started by doing a market study and then a business plan. My local SBA was extremely helpful in helping me cover the bases.

I also found assistance in my local Extension service, and the nursery industry associations are wonderful. I have no idea what organizations are out there for this type of enterprise, but you should join a tropical/indoor plant association just to stay informed about what's new and great.