Problems With No Fruit on Zucchini Plants

Zucchinis, which are also known as summer squash or courgettes, are summer vegetables which generally grow quickly and easily, given fertile, well drained soil, plenty of water and lots of sun. Zucchinis are best when they are picked small. When the zucchini fruit reaches over 10 inches, the skin toughens and the fruit loses flavor. Once established, zucchinis can fall prey to a few diseases and obstacles to fruiting, all of which can be overcome.

The zucchini plant has both male and female flowers and these must cross pollinate for the fruit to develop. The male flower can be identified by its long stem, and the female flower by the bulge of flesh behind the flower which will become the fruit.

The flowers are pollinated by insects, bees being the most common pollinators. If you have not seen bees at work in your garden, you can pollinate the female flowers with a fine paint brush such as a No. 3 or No. 4 watercolor brush. First brush the male stamen and then move the brush directly to the pistil in the center of the female flower. This is most effective when the flowers are young and at their best. Occasionally the zucchini plant will produce flowers of only one gender, generally male, early in the season. This will rectify itself as the plant matures. (Reference 1)

Downy or powdery mildew is the main disease which can shorten the life of your zucchini plant and rob you of fruit. This can occur in damp, cool summers, but unless you're having a very wet summer it can be avoided. Plant the seeds in clusters of two or three 3 to 4 feet apart to allow for airflow between the plants. Thin to one plant each. Some gardeners suggest staking the plants as they grow so that they grow up into the air. Water well in the early morning so that the sun will dry the leaves. A number of predators such as slugs, snails and beetles can take out your young seedlings, but using a large plastic bottle with the bottom cut out over your seedling will provide some protection. Don't leave this on during a hot day as it will cook the young seedling.

Sometimes you may see fruit develop on your zucchini plant which rot at the blossom end and do not grow beyond 4 or 5 inches, or wither at the end and are inedible. This problem is called blossom end rot and can have two causes. The first is a lime deficiency which can be prevented by spreading one handful of lime or dolomite per square yard before you plant the garden; dig it in well. The second cause is irregular watering. Deep watering at regular intervals can prevent blossom end rot if lime is present.

The best guarantee of good zucchinis is a healthy plant. In a well fed, well drained soil with a pH of 7, the plants should be vigorous and grow abundant fruit. Buy robust seedlings or thin your home grown seedlings to a single, strong plant when they are a few weeks old. This will increase your chances of a good crop.