DeficiencymediumJun–Sep

Potassium deficiency

Kalium-Mangel

This description was machine-translated.

How to spot it

You will notice potassium deficiency first on older, lower leaves: the edges turn yellow, brown and roll upward, while the veins stay green. In tomato the fruit at the stem base often remains hard and green (green collar), in potato and apple the leaves appear prematurely burnt and brittle. Because potassium is important for water balance and cell stability, affected plants wilt faster even on moist soil and react more sensitively to drought stress and frost.

Prevention

You can enrich the soil naturally with compost and wood ash in moderation, which also improves soil structure so nutrients are retained better. A crop rotation with fewer potassium‑hungry crops relieves the soil between intensive crops such as tomato and potato. Mulching protects against leaching from heavy rain and keeps moisture more even, which facilitates nutrient uptake. In sandy, well‑drained soils, incorporating organic material helps prevent potassium from leaching quickly into groundwater.