In a city you have more sources than you think and each is good at a different thing. Knowing which is which saves money and, more usefully, saves you from buying a plant your apartment cannot support.
No shops are named here and nothing is recommended. What this site earns from is not settled, and until it is, a page that starts pointing you at sellers is one whose motives you cannot check. What follows is the structure of the choice.
First, the thing that matters more than where you buy
Know which position the plant is going into before you leave the house.
That single habit does more for your success rate than any choice of source. A plant bought for a position is a plant that has somewhere to live. A plant bought because it was appealing is a plant that goes wherever there is a gap, which is the darkest part of the room.
The University of Illinois Extension puts Bright Light at an east or west window directly in front or a south window up to 5 feet away, Medium at a north window directly in front, an east or west window a few feet away, or a south window 3 to 10 feet away, and Low beyond that. Know which band you are shopping for. The room-by-room survey produces that list once and then you carry it in your head.
What each kind of source is structurally good at
Not a ranking. They genuinely serve different purposes.
The supermarket or grocery store. Convenient, cheap, and the selection is small and repetitive. Good for common, forgiving plants when you already know what you want. The plants have usually been indoors in low light for a while, which for a plant destined for a modest position is not necessarily a disadvantage.
A dedicated plant shop or garden center. Wider selection, and the important thing they offer is people who can answer a question about a specific plant. If you are unsure, this is worth paying for, and the question worth asking is the light one.
Online. The widest selection by far, and the only route to anything unusual. The trade is that you cannot see it, and it has a journey to make, which in winter is a real consideration.
A friend, or a cutting. Free, and the plant comes with the most useful information available: you have seen it growing in a home in your city, in a real apartment, in conditions like yours. That is better evidence than any label.
A market stall or a street seller. Frequently the best prices and the least information. Good when you know exactly what you are looking at.
The trade that actually matters in a city
Not price. Size and transport.
In a city you are frequently on foot, on a bus, or in a lift. A large plant is not just expensive, it is a logistics problem, and the point of purchase is where that gets decided.
Buy small if you are carrying it far. A smaller plant of the same species will get home undamaged and will grow into the position anyway.
Buy where you can get it home. The best plant in the city is not better than an adequate plant that arrives intact.
In winter, the journey is the risk, and that is worth planning separately from the purchase.
What to ask, whoever you are buying from
Two questions, and neither is about the plant's condition.
"How much light does this need?" Then match it against your band list. A seller who answers this specifically is worth returning to. A seller who says "it likes bright indirect light" about everything in the shop is telling you they do not know.
"How big does it get?" The mature size, not the current size. This is the question that prevents the most expensive mistakes and almost nobody asks it.
Assessing whether a particular plant is in good condition is a different skill and it is not this site's subject. What to look at, what to avoid and what the signs mean belong to people who cover that properly, and it is worth reading before a big purchase.
Buying for a difficult apartment
If your positions are modest, say your best window faces north, then where you buy matters less than what you refuse to buy. What a north-facing window supports sets out that band, and the useful discipline is to walk past everything that needs more.
The shop is optimized to sell you the plant you find attractive. Your apartment is not. Bring the list.
Buying for a studio
One room, contested surfaces, and every plant occupies something that was doing another job. What works in a studio covers the constraint.
For buying, the practical version: fewer and better. In a studio the marginal plant costs you a surface, and surfaces are scarcer than light.
The habit worth building
Do not buy on the day you first see it.
Go home, check the position, check the mature size, and go back if it still makes sense. Most regretted plant purchases are same-day decisions made in a shop that is designed to produce them.
The plants that do well in small apartments are almost always the ones somebody went and thought about first.
If you have pets
Check the species, by botanical name, against the ASPCA's toxic and non-toxic plants database before you buy rather than after it is standing in your kitchen. It is a two-minute check and it is much easier to do in a shop than to undo at home.
Frequently Asked Questions
Where is the best place to buy houseplants in a city?
There is no single best place, because each kind of source is structurally good at something different. A supermarket is convenient and cheap with a small repetitive selection, which suits common forgiving plants when you already know what you want. A dedicated plant shop or garden center offers a wider selection and, more importantly, people who can answer a question about a specific plant. Online has the widest selection and is the only route to anything unusual, at the cost of not seeing it and of the journey it has to make. A market stall usually has the best prices and the least information.
What is the best source of all?
A friend, or a cutting, and not only because it is free. The plant comes with the most useful information available: you have seen it growing in a home in your city, in a real apartment, in conditions like yours. That is better evidence than any label.
What should I ask the seller?
Two questions, and neither is about the plant's condition. How much light does this need, which you then match against your own band list. A seller who answers that specifically is worth going back to, and one who says everything in the shop likes bright indirect light is telling you they do not know. And how big does it get, meaning the mature size rather than the current size, which is the question that prevents the most expensive mistakes and almost nobody asks.
Should I buy a large plant or a small one?
In a city the real trade is size and transport rather than price, because you are often on foot, on a bus or in a lift. Buy small if you are carrying it far, since a smaller plant of the same species arrives undamaged and grows into the position anyway. The best plant in the city is not better than an adequate plant that gets home intact.
How do I avoid buying a plant I regret?
Do not buy on the day you first see it. Go home, check the position, check the mature size, and go back if it still makes sense. Most regretted plant purchases are same-day decisions made in a shop designed to produce them, and the plants that do well in small apartments are almost always the ones somebody went away and thought about first.
The part worth remembering
Every source in a city is good for something: convenience, selection, advice, price, or evidence from a real home.
The decision that matters is not which one. It is knowing the position and the mature size before you go, and being willing to leave without anything. If you have not built the position list yet, that is the thing to do before your next trip, not after it.