Why Are My Radish Leaves Turning Yellow?

Radish leaves that were green and healthy are now yellowing — either the lower leaves first, or all leaves at once, or with a patchy, blotchy pattern. Because radish has such a short growing season, yellowing at any stage can compromise root development if not addressed quickly. The pattern of yellowing — which leaves, how it spreads — guides you to the most likely cause.

Overwatering and waterlogged roots

Radish grown in waterlogged soil cannot absorb oxygen at the roots and the roots begin to die. The leaves yellow as the plant struggles. This is particularly common in heavy clay soils after persistent rain. The entire plant yellows relatively uniformly. Improve drainage; in raised beds, check that drainage is unobstructed. Allow the soil surface to dry between waterings. If the soil has been saturated for more than a couple of days, the roots may already be rotting and the plant cannot be saved — remove and resow.

Nitrogen deficiency — lower leaves yellowing first

Nitrogen-deficient plants show yellowing from the oldest (lowest) leaves first, progressively working upward. In average garden soil radish rarely needs additional feeding — the fast growth cycle means it should use whatever nitrogen is already in the soil. However, in very poor sandy soils or after several consecutive crops have depleted the bed, a light balanced liquid feed can correct this quickly.

Root maggot damage

Cabbage root fly larvae tunnelling through the roots cause the same wilting and yellowing symptoms as overwatering — the damaged root simply cannot supply water and nutrients effectively. The key distinction: if the soil moisture appears adequate but leaves are yellowing and wilting, dig up a plant and examine the root for tunnels and small maggots.

Downy mildew

Downy mildew (Peronospora parasitica) causes angular yellow patches on leaves, bounded by the veins. On the underside of the leaf, a grey-purple downy coating may be visible in humid conditions. Downy mildew is most common in cool, wet conditions. Improve airflow, avoid overhead watering and apply copper fungicide at the first sign if symptoms are progressing rapidly.