Sitaphal milkshake recipe - The winter season is here but the temperatures are still warm. Climate is warm during days and cool during nights. Here in India, the season for custard apples or sitaphal starts from mid-July and ends in late-November. I usually buy custard apples whenever I find nice big ones at a good price, but I buy them hard. In our warm weather, they ripen overnight. Then I keep them in the refrigerator. The custard apple season comes just once a year. I store custard apple pulp in the deep freezer when custard apples are in season.