QUESTION: My potato plants are not flowering. How do I know when to harvest them? Do potato vines have to flower before harvesting? Or does it depend on the type of potato? -Matt G
ANSWER: Don’t worry if your potato plants aren’t producing blooms. The flowers are not needed in order for the plants to grow delicious tubers underground. Instead, the blossoms are linked to production of the small, green above-ground fruits that resemble tomatoes. Despite this resemblance, the fruits of the potato plant are poisonous and should never be eaten. They contain a toxic level of solanine, a poisonous alkaloid that forms when parts of the potato plant are exposed to sunlight.
Solanine is the reason parts of the potato tuber turn green when they are in contact with sunlight. These greenish parts of the potato must be cut away before the potato is consumed. All above-ground portions of the potato are poisonous and should not be eaten, including the flowers, stems, leaves, fruits, and any tubers that remained above ground. Consumption of parts of the potato that contain solanine can cause confusion, diarrhea, digestive discomfort, drowsiness, vomiting, shortness of breath, and weak or rapid pulse, and if solanine poisoning is not treated, the person who consumed it can die due to respiratory failure.
If you grow potatoes and your plants didn’t bloom out, you may be wondering how you can tell when you have mature potatoes (Some gardeners recommend waiting for the flowers to fade away before digging up potatoes.) In home gardens, the best way to know when it’s harvest time is to watch for the foliage of the potato plants to wither, go dry, and fall over as a signal for you to start harvesting your potato crop.