Plants like sunflowers don't grow well in the shade. When sunflowers were put in low light, they got smaller and their leaves didn't grow as much. Their growth rate slowed down a lot, especially in deep shade. The amount of leaf area compared to leaf weight changed with less light, making them less able to tolerate shade. The part of the plant that doesn't do photosynthesis got bigger in the shade, which is bad for growth. Overall, sunflowers don't like shade because their leaves don't grow enough and other parts of the plant get too big.