• Skip to main content
  • Skip to footer
  • Garden design
  • Container gardening
  • Food to grow
  • Gardens to visit
  • Events for gardeners
Garden Making

Garden Making

Inspiring ideas and information for great home gardens

Home » Bacterial inoculant improves spring peas

Bacterial inoculant improves spring peas

By Judith Adam Filed Under: Making a Garden

A bacterial inoculant helps boost nitrogen fixing in peas. (Photo by Brendan Zwelling)
A bacterial inoculant helps boost nitrogen fixing in peas. (Photo by Brendan Zwelling)

I’m perfectly aware that the ground is frozen solid, and there are eight to 10 weeks of waiting before trowels and shovels can go into the soil. What’s a gardener to do, but live in hope and order seed for spring planting? My early plantings of peas were especially productive last year, most likely because I remembered to use a bacterial inoculant to boost their nitrogen-fixing ability.

Peas are legumes (just like dry beans, runner and bush beans, and soybeans), and have the ability to grab atmospheric nitrogen from air and fix it in solid form on their roots as ammonia nitrogen. The result of this process is that legumes can manufacture a considerable amount of the nitrogen they require. Legumes will attempt to do this without assistance, but using an inoculant at planting time greatly increases plant productivity.

Inoculant products contain living rhizobium bacteria, a benign organic material that should be kept refrigerated (but not frozen) for best viability, and the package should have an expiration date. Rhizobium bacteria form a symbiotic relationship with plant roots, producing results that are mutually beneficial to both partners. The bacteria are instrumental in encouraging legume roots to form the small lumpy root nodules that are mini-factories for ammonia nitrogen production. It’s interesting to examine the roots of legumes, looking for these nodules. When pea or bean plants are finished and lifted from the soil, carefully ease one clump out and spray a fine stream of water over the roots. Look carefully, and you might find small bumps along the roots. Those are the nitrogen-fixing nodules. (You can also do this with a clump of white clover, another legume, carefully eased out of the lawn in midsummer.)

Inoculant products come in several forms — solid, liquid and freeze-dried. The product prepared for home gardening is usually a packet of dust-like black powder that can be purchased at a garden centre (usually near the seed displays) or through seed catalogues. There are several species of rhizobia bacteria, and it’s important to get the right one for the plant you intend to grow. Soybeans will need a particular species of rhizobia, while another species is compatible for peas, lentils, snap and lima beans. This information is always printed on the package, and should also be available when purchasing inoculant through a catalogue.

Using inoculant is quick and easy. When ready to plant peas or beans, put the seeds into a plastic container and spray them lightly with water (no big drops). Then sprinkle the rhizobium over the seeds and swirl them around to coat in the black powder. Proceed with planting, tapping the seeds out of the container and into the furrow carefully so that not too much of the inoculant is brushed or knocked off. There’s no problem touching the inoculant with bare hands, but using fingers to plant the seeds will remove some of the powder.

All this encouragement about planting peas is making me think of what more I can grow with inoculants. For more information about inoculants, see http://www.ext.colostate.edu/pubs/crops/00305.html#top

Print Friendly, PDF & Email
Share this article

Published: February 10, 2013 | Updated: February 6, 2019

About Judith Adam

Judith Adam is a horticulturist, landscape designer and author of several best-selling gardening books, including Landscape Planning. She lives in Toronto.

Reader Interactions

Leave a Reply Cancel reply

Your email address will not be published. Required fields are marked *

Footer

Garden Making website

explore

  • Books for gardeners
  • Containers in your garden
  • Events for gardeners
  • Food to grow
  • Garden design
  • Gardens to visit
  • Growing from seed
  • How to
  • Plant ideas
  • Prizes for readers
  • Tips for gardeners

Members

  • Member login
  • Register for free membership
  • Manage your email preferences
  • Add your event listing
  • View events you’ve submitted
  • Backup form to submit event

Events for gardeners

May 24
7:30 pm - 9:00 pm

Catherine Kavassalis on herbs

Organizer: Brampton Horticultural Society
Laura: 905 799-1929
May 25
7:00 pm - 8:00 pm

Peterborough Horticultural Society Monthly Members’ Meeting – IN PERSON YAY!

Organizer: Peterborough Horticultural Society
416-846-0778
May 25
7:00 pm - 8:00 pm

Joyce Hosty on Foodscaping: Edible Landscapes

Organizer: Peterborough Horticultural Society
May 27
6:00 pm - 8:00 pm

Selkirk Annual Plant Sale

Organizer: Selkirk & District Horticultural Society
(204) 738-2368
May 28
8:00 am - 12:00 pm

Bronte Annual Plant Sale

Organizer: Bronte Horticultural Society
View Calendar

Get email updates

Join 9,703 gardeners who get our email updates. We do not share emails.

Check your inbox or spam folder to confirm your subscription.

Copyright © 2022 Inspiring Media Inc. | GARDEN MAKING is a registered trademark | About | Service | Terms of use | Privacy policy