By Janelle Rietz-Kamenar
Have you ever grown purple string or snap beans? They mature on the vine purple but when steamed, transition to the normal green bean color. They are also great raw in salads that show off their unique color. There are now various varieties available ranging from snap-type bush and pole string beans. What an interesting table conversation for new gardeners young and old! Read more to learn how to grow these beans.
Purple bean seeds are sold under a plethora of names such as Purple Queen, Royalty Purple and Royalty Burgundy, to name just a few. Purple beans are grown just like other green beans but are easier to spot on the vine during harvesting. What gives them the purple color is a natural group of chemicals called anthocyanins that are also found in other fruits and vegetables such as grapes, plums, and purple broccoli.
One benefit of growing beans is that they don’t need a lot of fertilizer compared to other plants. In Minnesota, beans should be planted starting in late May or even early June when the soil is warm. Bush beans can be planted in succession every two weeks up until early August while pole beans will continue to flower and bear until frost, so no succession planting is needed. Follow the packet seed directions for planting based on the type of seed purchased. However, if you are growing the pole bean type, make sure to have the trellis structure in place prior to planting. Provide enough air circulation around the plants and control weeds in order to reduce the spread of viruses and insects.
When do you harvest these purple beans? You can harvest them at any pod formation stage, until the shape of the individual seeds inside becomes apparent, causing the pods to bulge. After this point, the pods are usually more fibrous and less juicy. After picking, they do hold their quality for several hours at room temperature, but you should refrigerate them if you don’t eat or cook them immediately.
Therefore, if you want to add some additional color into your salads or have an interesting table conversation, try growing these uniquely colored green beans!
Sources:
https://extension.umn.edu/vegetables/growing-beans
https://www.csmonitor.com/The-Culture/Gardening/2009/0909/the-science-behind-purple-beans