Tomatoes are heavy feeders with highly specific macronutrient and micronutrient requirements that shift significantly across their growth stages. Nitrogen drives vegetative development early in the season, but excess nitrogen post-flowering redirects energy away from fruit set and into foliage. Calcium deficiency — one of the most common issues home growers encounter — typically manifests as blossom end rot and is frequently misdiagnosed as underwatering, when the actual cause is either a soil calcium deficiency or impaired uptake due to inconsistent irrigation. The Nutrient Deficiency Chart maps observable symptoms to their root causes so growers can intervene accurately rather than reactively.