High Nitrogen, Low Potassium: Why Vegetables Grow Tall But Fruit Poorly

Excess Nitrogen Favors Leaves Over Fruit

A soil test showing high N and low K explains the symptoms: vines and stems grow luxuriantly, but flowers and fruit are scarce. Lawn fertilizers (e.g., 29‑4‑8) are high‑N; using them on tomatoes creates “jungle” plants with few tomatoes.

Fix

Apply a balanced or high‑potassium fertilizer (like 5‑10‑15) and avoid lawn‑type products on vegetables.