A Newly Planted Zucchini Is Turning Yellow

Healthy zucchini plant leaves are deep green.

Healthy zucchini plant leaves are deep green.

A fast grower, zucchini (Curcurbita pepo) plants can quickly overtake a garden with their broad leaves, vines and fruit. A warm-weather vegetable, zucchini is one of the easiest plants to grow in a home garden. Too much yellowing on a zucchini plant’s leaves is a sign your zucchini plant is unhealthy. Yellowing on the plant leaves, also known as chlorosis, is a symptom of unsuitable growing conditions.

Cucumber Mosaic Virus

Because zucchini are in the same family as cucumbers (Cucumis sativus), cucumber mosaic virus can also affect zucchini. Signs of a virus infection are patches of yellowing on the leaves, usually along the veins. Cucumber mosaic virus is usually transmitted by aphids, tiny insects that attach themselves in large numbers to the undersides of leaves. Once infected, there is no cure for the virus. Remove infected plant parts to stop the virus from spreading as the infection often causes stunted growth and poor fruit development.

Spider Mites

Often undetectable at first glance, spider mites suck the sap from the leaves of the zucchini plant. This leaves many small yellow stipples along the leaf. Because they're so small, the first indication of a spider mite problem is when the damage to the plant first becomes visible. Spider mite infestations can be treated with a ready-to-use insecticidal soap. Spray all the leaves thoroughly, including the undersides.

Soil Preparation

A well-prepared soil leads to healthy zucchini plant growth, while waterlogged and compacted soil can cause poor root development and growth. Before planting, mix in compost and other organic matter into a well-tilled soil to improve its overall structure. If your garden has heavy clay soil, consider adding peat moss and compost to lessen the chance the soil will become too compacted over time.


Conduct a soil test before planting to ensure sufficient nutrients and the appropriate pH level. Zucchini plants prefer soil that is slightly acidic or neutral with a pH of 6.5 to 7.0, and as heavy feeders, nutrient-rich soil is ideal. Deficiencies in manganese, sulfur and iron will cause yellowing in the younger leaves of the plant first, before progressing to more established leaves.

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