Potatoes planted in March and April can be harvested in July and August, but do not eat potatoes that have turned dark green as they may be poisonous.
Potatoes that look like this are potentially highly poisonous (Alex Evans)
Gardeners, take care this summer!
If you plan to harvest your home-grown potatoes in July and August, avoid greenish potatoes. If you plant potatoes in the spring in March and April, early varieties will be ready for harvest in July and late varieties will be ready for harvest in August.
If you have a potato patch or grow bags, you'll want to keep an eye out for telltale signs that your potatoes are ready to come out of the soil. Flowering plants are a good indicator that harvest time is near. After flowering, watch for the stems to droop and the leaves to turn yellow, according to the Express.
Ideally, you should wait a week or two after the leaves have died before harvesting to allow the potatoes to grow to their full potential without rotting in the ground, but if you do dig up any green potatoes, don't eat them; they can be poisonous.
This green colour is often caused by too much light and is due to chlorophyll – it can happen if the potato is not buried deep enough or if the soil shifts and exposes it to sunlight – but the green colour can also indicate the presence of harmful chemicals that can make you sick if ingested.
The U.S. Department of Agriculture warns: “Potato tubers are specialized stems of the potato plant, and tubers exposed to light naturally turn green. The green color is nothing but chlorophyll, a harmless compound found in all green plants. However, when potato tubers turn green, it is usually due to an increase in a glycoalkaloid compound called solanine. Therefore, it is important to store potatoes out of light to prevent greening.”
“Tubers with high levels of solanine have a bitter taste and are harmful if eaten in large quantities, so to be safe, it's best to avoid eating the green parts of the tubers.” EatingWell adds: “Potatoes with green spots or sprouts may contain the toxin, so if you can't completely remove those parts, it's best to throw them out. Store potatoes in a cool, dry, dark place to prevent them from sprouting or spoiling prematurely.”
