Question: In early fall, my broccoli plants were growing beautifully, but then the heads of broccoli were covered with yellow flowers. Why, and what can I do to prevent this from happening again?

Answer: Your plants bolted, perhaps because of high temperatures, lack of moisture, or poor soil conditions. Broccoli grows best in cool weather. When it gets too hot the flower buds that make up a head of broccoli quickly open up into the yellow flowers you see. There's no way to save your plants once they've bolted. In the future plant your broccoli when it can grow during moderate to cool temperatures.