Chayote requires at least 120 days of frost-free, warm and sunny weather to reach maturity when grown as an annual from seed. The squash may mature more quickly or slowly, depending on the current year's weather and local growing conditions. Starting seeds indoors in early spring can ensure the chayote has time to ripen in areas with short growing seasons. In areas where chayote grows as a perennial, it usually ripens in late summer after four or five months of warm weather.
Harvesting chayote when the fruits are still young and tender results in the best flavor. A ripe chayote has bright green skin you can pierce with a fingernail. The fruit feels firm but gives slightly when squeezed. Some chayote varieties produce hair-thin spines as the fruit matures further. To ensure the softest flesh, easiest handling and edible skin, harvest the chayote when it's still young and tender enough that the skin hasn't begun to develop extensive spines or harden.
Avoid pulling on the chayotes when harvesting because this can damage both the squash and the plant. Chayote produces a sap that causes skin irritation. Wear gloves when harvesting and handling the chayote to prevent contact with any sap. Gloves also protect you from any spines on the fruit. Harvest every other day when the fruits begin to ripen. This ensures the chayote don't become overly mature and helps keep the plant productive.
Picking chayote at the peak time only works if you use or store the squashes promptly after harvest. Store the chayotes in the crisper drawer of the refrigerator for up to one week. Place them in a paper bag if the chayotes have spines. The spines won't tear through paper as easily as they would plastic. If you must store the squash for a long period, peel and dice it into small pieces. Store it in a ziptop storage bag in the freezer for up to 12 months.