This study establishes the regularities of dry organic matter accumulation throughout the growth period of drip-irrigated tomato (Solanum lycopersicum L.), cultivated in the cold semi-arid climate zone (BSk), under various watering thresholds using a logistic function. The proposed mathematical models highly conformed to the empirical data, yielding strong coefficients of determination (R2 of 0.98). Growth parameter modeling demonstrated that maintaining a soil moisture threshold in the layer 0-50 cm of at least 70% field capacity (FC) from seedlings planting to budding, followed by 80% FC during peak growth intensity, optimizes biomass accumulation dynamics. The absolute highest dry organic matter accumulation rate (0.623 t ha-1 day-1) was recorded at the critical curve inflection point (T2) under a dynamic 70–80–70% FC irrigation regime. Peak growth acceleration (0.024 t ha-1 day-2) occurred at critical point T1. The intensive growth phase terminated upon reaching critical point T3, transitioning into a deceleration phase characterized by negative acceleration values, which temporally coincided with intensive fruit formation. The duration of this intensive growth window varied from 13.2 to 19.1 days depending on moisture availability. Ultimately, maintaining soil moisture below 70% FC or exceeding 80% FC is agronomically impractical because these moisture extremes significantly depress both growth rate and acceleration, reducing overall crop productivity.