Veggie Garden 101: Inoculating Beans and Peas

Inoculating green bean (aka snap bean) seed. Photo: Liz Bosak.

Peas, green beans, dry beans, and soybeans all belong to the legume (Fabaceae) family. Legume plants can form an association with soil bacteria. A particular group of bacterial species will infect the roots and create nodules. Within these nodules, the bacteria will fix nitrogen. Nitrogen is one of the most critical plant nutrients along with phosphorus and potassium. If you have ever bought fertilizer, it will be labeled with three numbers, e.g. 15-30-15. The first number is nitrogen, second is phosphorus, and the third is potassium. The numbers mean that in 100 lbs of fertilizer there is 15 pounds of nitrogen, 30 lbs of phosphorus, and 15 pounds of potassium in 15-20-15.
If you are planting beans and peas into a new garden, it is a good idea to use an inoculant. This was a difficult product for gardeners to source at one time but it is now sold in small quantities by most seed retailers. It is important to pay attention to the description for which legumes the bacterial formulation will be effective on.
For inoculation, I drop about a half teaspoon of inoculant in a plastic container and then add a small amount of water to create a slurry. Drop a handful of seeds into the container and swirl the seed to coat. The other method is to sprinkle the inoculant in the seed furrow before covering the seeds with soil.

Add a small amount, about a half teaspoon of inoculant into a plastic container.  Photo: Liz Bosak.

Add a small amount of water.  Photo: Liz Bosak.

Drop seeds into the inoculant and swirl to coat the seeds. Photo: Liz Bosak.