Tomatillos are generally harvested when they are not fully ripe. This is because green tomatillos have a tart flavor that is useful in salsas and other sauces. If allowed to ripen further, tomatillos turn purple or yellow and have a sweet flavor and many more seeds. Determining when to harvest your crop of tomatillos is fairly simple.
Keep track of the date the tomatillos were planted. The plants' fruit should be ready to harvest within 75 to 100 days of transplanting them into the ground or a pot.
Monitor the husks once the fruit appears. Tomatillos have a thin husk around the fruit that is a good indicator of when it is ready to harvest. When the husk appears papery and light brown, the tomatillo is ready to harvest. The husk will be split and will have slightly pulled away from the fruit, which will be very firm.
Pluck the tomatillo from the plant with your hand. If it is too hard to remove, use a pair of gardening scissors to cut through the vine where it connects to the fruit.
Store the harvested tomatillos in the refrigerator for up to three weeks. For best results, put them in a paper bag first.