Pruning and Trellising
The needs of your zucchini plants will depend a bit on which type of zucchini you’re growing. Bush-type zucchini do not require trellising or pruning, though it is best to remove any damaged leaves by cutting them off near the base.
Vining varieties, like heirloom Italian zucchini, require more space than their bush-type counterparts, but you can keep them from taking over by training them to grow on trellises. You can also prune away unruly vines, but keep in mind that this will reduce the yield since it limits the number of flowers each vine produces.
Feeding and Watering
Zucchini are heavy feeders, which means they prefer nutrient-rich soil. It’s best to prepare your soil before planting, but you can give your plants a boost mid-season with phosphorous-rich fertilizer. Water-soluble mixes, like fish emulsion, can be applied to the leaves as a foliar feeding, while granular mixes should be applied to the soil near the base of the plant.
For the best harvest, zucchini plants need at least one inch of water, either from rain, irrigation, or a combination of the two. With the exception of foliar feeding, avoid overhead watering to reduce the risk of fungal diseases. Drip irrigation or soaker hoses are a more effective option.
Diseases and Treatments
Though zucchini are hardy plants, they are prone to several diseases, especially those spread by pests. Prompt treatment is the best way to keep these diseases from spreading.
- Cucumber Mosaic Virus: Often spread by aphids & other pests. Look for patchy yellowing in the leaves and stunted, misshapen fruits. Remove any affected foliage, and cut down on aphids by using insecticidal soap.
- Powdery Mildew: A fungal disease which causes a powdery white build-up on leaves. Prevent it by growing in well-drained soil and avoiding overhead watering. Treat affected plants with a copper fungicide.
- Squash WiltThis incurable bacterial disease causes the entire plant to wilt and die. It is spread by cucumber beetles, so prevent them from feeding by using row cover or by spraying with neem oil.
Most types of zucchini are ready to harvest when the fruits are 6-8 inches (15-20 cm) long. Small fruits are typically more tender and flavorful, and have fewer seeds. Some varieties, however, especially heirlooms, retain their texture and flavor even when they’ve grown quite large. Harvest fruits by slicing their stems with a sharp knife.