Why is my lemon tree not producing fruit?

Common reasons: the tree is seed-grown (takes 5–7 years vs 1–2 for grafted); insufficient sunlight — less than 6 hours daily directly reduces flowering; excess nitrogen feeding promotes leaves over flowers; no stress cycle — lemon trees fruit better after a brief dry period in winter (reduce watering October–November); or the tree is too young. Feed with potassium nitrate foliar spray to trigger flowering on mature trees.