PHOTO: Jessica Walliser
March 16, 2017

Peas are among the earliest of crops to go into the spring garden. They’re tolerant of cold soil, and they need to produce their pods before summer’s heat arrives and the plant dies. There’s a better way to grow peas than by simply going out and plunking a few pea seeds into the soil. Using pea inoculants is the first step to growing a hearty crop of productive plants.

What Are Pea Inoculants?

Pea inoculant is a microbial amendment that’s added to the soil at the time of planting. Inoculants are granular products comprised of millions of live bacteria. These bacteria colonize the roots of pea and bean plants, forming nodules on them. The bacteria in the nodules form a symbiotic relationship with the pea roots, converting nitrogen from the air into a plant-accessible form. Because of this relationship, when using pea inoculants, no additional nitrogen fertilizers have to be added to these crops.

Although these naturally occurring bacteria are often already present in organic soils, especially where peas and beans have been grown before, purposefully introducing pea inoculant to the soil at planting time results in quicker root colonization. This, in turn, leads to improved germination rates, bigger, healthier plants, more extensive root systems and improved yields.

All members of the legume family have the ability to form these nitrogen-fixing nodules on their roots, and there are numerous species of bacteria used to inoculate leguminous crops to encourage the process. For peas and beans, the best species is Rhizobium leguminosera. Other species of microbial inoculants are useful for alfalfa, clovers and other members of the legume family.

How To Inoculate Pea Seeds

There are several ways to introduce pea inoculant products to your pea seeds.

  1. Dampen the pea seeds with a small amount of non-chlorinated water. Put the granular inoculant and seeds in a bag, and toss them together until the seeds are coated. Plant the seeds soon after.
  2. Coat dry pea seeds with inoculant by sprinkling the granules down the planting row after placing the seeds in it.
  3. Liquid inoculant products are an excellent way to inoculate the seeds of commercial-sized plantings. The seeds can be dampened with the liquid prior to planting, or the liquid can be poured over the seeds after they’ve been placed in the seed furrow.

Don’t worry about over-applying pea inoculant because other than costing you money, too much inoculant will not hurt the plants.

More Tips For Using Pea Inoculants

Here are a few other things to keep in mind when using pea inoculants.

  • Acidic soil can impact these bacterial and their usefulness, so prior to planting peas, ensure your soil’s pH level is as close to the ideal 6.5 as possible. It’s a measurement that’s perfect for both optimum pea growth and optimum bacteria root colonization.
  • Some of the nitrogen fixed in the root nodules is used to fuel the current year’s pea crop, but some also stays in the plant tissue. When that remaining plant material is turned into the soil and left to decompose, it goes on to feed future plants. That’s why cow peas, vetches, clovers, alfalfa, and other legumes are often used as cover crops and tilled into the soil.
  • Tossing pulled pea plants into the compost pile also adds plant-accessible nitrogen to the finished compost.
  • Follow the same technique when planting all types of bean seeds, too, as they too will give bigger yields and have improved growth and health when inoculants are used.

They may be invisible to the gardener’s eye, but the beneficial bacteria introduced when using pea inoculants impact plant health and production in a big way.


Next Up