Jethro Day discusses Luke 13:1-9, emphasizing Jesus' message of repentance. He explains repentance as turning towards God and aligning with His agenda, essential for life and goodness. Jesus uses the metaphor of fruitful trees to illustrate spiritual growth and contrasts it with barren, prickly ones. Day suggests four practices for spiritual fertilization during Lent: fasting, prayer, generosity, and scripture reading. He highlights the importance of being relationally connected to God and living a fruitful, giving life, while acknowledging God's compassion and grace.