Updated: Sep 10, 2021
Zucchini can be harvested at the moment they reach a usable size about 6 to 8 inches in length
Generally zucchini is harvested when its tender and they have good flavor when they are young. Also smaller fruits have superior taste
Zucchini can grow 1 to 2 inches a day
Zucchini that grows very large will be pulpy, seedy, and bitter flavored.
Carefully cut fruits off the plant with a knife or pruners when zucchini are between 3 and 8 inches long. Leave about two inches of the stem to remain on the fruit.
To help them store longer, harvest with at least an inch of stem still attached.
If grown correctly and healthily, you should be able to harvest zucchini multiple times in one growing season.