You could technically keep it in a very small pot. The only thing you need to make sure you do is perform regular root maintenance, root prunning and re potting, which will keep your lemon nice and happy. Since you are mainly growing it for the flowers, you wouldn't technically need a very big pot. But if you wanted a nice full plant that produces lots of flowers, I would think eventually a 12 inch pot would suffice.

Kristopher

Thanks a lot, Kristopher.

Another question:
Would a terra cotta pot be fine? Or Meyer lemons prefer plastic / or Fabric Pots?

If you're bringing your tree indoors in winter and it will be housed in a room or near a window that can get chilly, I would not use a terra cotta pot. Been there, done that, the moist clay gets very cold, affecting the temp at the roots. It stressed my trees. They seem much happier in plastic or ceramic. Mine were in a room that ranged 55-65 at night in winter, and they were situated close to the west window. Just a thought...

Lose the terra cotta in your zone. Evaporation from the TC cools the soil and citrus roots do not like to grow into cool soil. Plastic, polymer, or even glazed pots are much better.

Ok, THanks a lot John & mandarin. I'll go for a plastic one.
Anyway they're lighter :)