Why won't my lemon tree produce lemons, and what can I do to encourage fruit production?

Lemon trees may not produce fruit due to factors like insufficient sunlight, improper watering, or lack of nutrients. To encourage fruit production, ensure the tree gets at least 8 hours of sunlight daily, water it consistently but avoid overwatering, and use a fertilizer high in nitrogen and potassium. Pruning and pest control can also help promote fruit growth.