Do you know how to tell when an apple is ready to be picked? According to South Dakota State University Extension Horticulture Expert Rhoda Burrows, sometimes the best way to know when apples are ready to harvest is the good old fashioned taste test. Another indicator, Burrows said is to slice open a few apples, and check the seed. The seed will turn brown when the apple is ripe. What about a hard freeze, which is when temperatures fall below 28 degrees Fahrenheit? Burrows says if one is predicted, and the apples are nearly ripe, it is probably better to go ahead and harvest the apples, and let them finish ripening in storage.