Can you still eat broccoli when it gets old and starts to flower?
Generally speaking, whether overripe or blooming broccoli is still edible depends on its specific condition. If there are signs of spoilage, it is recommended not to consume it. The detailed analysis is as follows:

If the broccoli has become overripe or started flowering but only shows loose curds and small buds, with leaves still fresh green and not yellowing or wilting, no unpleasant odor, and no slimy or soft texture upon touch, it is still safe to eat. You may extend the cooking time slightly. Although the texture won't be as crisp and tender as fresh broccoli, most of its nutritional value remains.
However, if the broccoli's curd develops mold spots, the leaves turn yellow and rot extensively, feels sticky to the touch, and emits abnormal odors such as sourness or decay, it has already spoiled and should absolutely not be eaten, as consumption may cause gastrointestinal discomfort.
When purchasing broccoli, try to select ones with compact curds and fresh green leaves. After bringing it home, wrap it promptly in plastic wrap and store it in the refrigerator to minimize moisture loss. Carefully inspect its condition before cooking, and discard any spoiled portions immediately to prevent contamination of the unaffected parts.