I love your idea of growing tropicals in pots. Those large size nursery pots (15 to 20 gallons) should keep any tropical happy for at least 5 years as long as remember to fertilize and don't let the soil dry out. As for your Meyer Lemon it should be happy in the one gallon container all summer unless you can see roots trying to escape the drainage holes or if the plant is so rootbound that water just runs right out of it. Transplant it to a 5 gallon container once you move it indoors for the winter or when it becomes dormant.  Keep growing, Marianne Binetti