The following is a letter by Srila Prabhupada to a disciple clarifying the function of sex in Krishna conscious grahastha life.
My Dear Shama Dasi,
Please accept my blessings. I beg to acknowledge receipt of your letter of January 14, 1969, and I was very glad to hear from you.
You have asked me some questions about the functions of sex life in Krishna Consciousness, and the basic principle is that it should be avoided as far as possible. However, if it is unavoidable, then it should be utilized only for begetting Krishna Conscious children. In that case, the husband and wife should chant at least fifty rounds before going to sex. The recommended period is six days after the menstruation period.
I am glad to hear that you are helping out in tending the Deities. This is very spiritually beneficial engagement and, along with chanting the required number of rounds of Hare Krishna, Krishna is sure to give you all facilities to perfect your life in full Krishna Consciousness. In this connection, the recipe for the charinamrita is enclosed here by Kartikeya.
Please continue to inform me of your progress in remaining at New Vrindaban. I hope this finds you in good health.
Your ever well-wisher,
A.C. Bhaktivedanta Swami