Sunlight hits the leaves first, and that is the real opening scene: a lemon tree in a pot can set fruit when photosynthesis supplies enough carbohydrate for flowering, fruit set, and leaf maintenance. A pot is not a prison. Ground soil is only one delivery format for water, mineral ions, and room for roots.
Root volume is the pressure gauge. When roots circle a cramped container, reduced aeration and poor drainage can suppress root respiration, while erratic watering disrupts transpiration and nutrient uptake. Treat the plant like a constrained server rack: its throughput is capped by cooling, power, and capacity. The scientific terms are oxygen diffusion, hydraulic conductance, and root-zone volume. Bigger pots buy margin; they do not create fruit alone.
Fertilizer is often oversold. Excess nitrogen can push leafy growth at the expense of bloom, whereas balanced feeding, bright exposure, and free drainage let the tree allocate carbon and minerals toward fruit. Prune with restraint. A compact canopy can match a compact root zone, but stripping leaves cuts the photosynthetic factory that fills lemons with sugar and juice. Multiply that logic across balconies, and spare light becomes a distributed citrus network.