Inoculum for Legumes

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Shipping fee is included! (Within the contiguous US). Choose from 10 different rhizobial inoculum strains. 1 bag will inoculate up to 1 pound of seed. Approximately 1 teaspoon of inoculum per bag.  

Most legume species harbor beneficial bacteria called rhizobia on their roots. Genus-specific strains of this bacterium called inoculum can aid in the fixation of atmospheric nitrogen and improve long-term health of native plant communities, especially in low fertility soils.

HOW TO USE: Add inoculant to dampened seed and mix thoroughly.
WHEN TO ADD: At time of cold, moist stratification, or if direct seeding, as close to planting time as possible.
SPECIAL CARE: Protect inoculated seed from sunlight or drying winds - cover seed as quickly as possible with soil or mulch.
ALTERNATIVE METHODS: Inoculant can be mixed with potting soil when planting in flats or peat pots; directly in the seed furrows along with seed at time of transplanting; or to potted plants by making a hole with a pencil. Inoculum may also be added to potting mix for container grown plants or into the bottom of a hole when transplanting container grown or bare root seedlings.

*If you are needing inoculum for a specific legume genera that we no longer carry (Crotalaria, Glycyrrhiza, Lathyrus, etc.) the rhizobium in the Baptisia, Desmodium, and Lespedeza inoculum tend to be less specific about which species they associate with and may be worth trying.  

9 Questions asked on Inoculum for Legumes

It is effective to apply inoculum to seedlings that have already sprouted in indoor containers? What about something like an existing Baptisia plant growing outside that was planted in post-construction exposed subsoil of questionable quality?
Thanks for writing, Chris. The bacteria in the inoculums that we carry for legumes typically are already present in most healthy soils. They do not affect plant germination but do establish symbiotic relationships with developing roots to enhance the formation of nodules that absorb atmospheric nitrogen. Adding inoculum to soils is an effective way to introduce or increase the population of beneficial bacteria.
Hello, do you offer inoculum for Thermopsis? Thanks!
Hi Maggie! We do! It's the same as the Baptisia Inoculum.
How do you choose the best type of inoculum for your soil? Are certain inoculums better for specific plants or seedlings?
Hi Pam. You really only need to consider purchasing inoculum if you are ordering Legume species - those in the pea family. This Inoculum order page lists the various legume genus', or you can find them by typing 'legume' in the search bar.

If you have very degraded soil, perhaps all organic matter was stripped off from construction, then you could consider our Mycorrhizal Inoculum for Exposed Subsoil, sold by the lb.

Does the inoculum keep well for future seasons? Due to variety of species, I’ll need to buy much more than I can use in one season.
Hi Olivia, Good question! If kept refrigerated, the inoculum will stay viable for at least a year, probably a bit more.
I have a few legume species that I would like to direct seed this fall (Amorpha, Chamaecrista, Lupinus). The soil is not the healthiest and has only been lawn. Would you recommend a separate inoculum for each species, or would one inoculum work for all?
Hi Daniel, Different genera of legumes tend to make associations with different strains of nitrogen fixing bacteria. In most instances this bacteria will be present in the soil, but if you are worried about the quality of the soil, you should get the three appropriate strains for each genus.
I wonder how to store this product when not in use, and how long, if properly stored, this product will last. Is it useful only for a single growing season, or might I expect to get several seasons' worth of use with pea plants?
If kept in the refrigerator in a sealed container, the inoculum will be good for a year, maybe a little longer.
How much inoculum do you receive and how many seeds will it inoculate?
Hello Tim, you receive a 1/2 tablespoon of inoculum and it will inoculate up to 1 lb. of seed.
How do I know what inoculum to buy for my seeds
Hi Renee. Determine the genus of your species (ex: Wild Blue Indigo is Baptisia and Wild Lupine is Lupinus). Select that genus name from the "Choose Type" drop-down menu.
Hi, we are planning to germinate Hedysarum boreale and several milkvetches (Astragalus). We've had past success with milkvetches, not so much with the sweetvetch. Do you have any strains that are compatible with intermountain milkvetches and sweetvetch?
Hi Diane. We do not have in-house experience determining which inoculum strains nodulate on what plant species, but if the species you are sowing is included in the exact genus listed in our inoculum (like Astragalus), we recommend that. Otherwise, our supplier has shared that the Lathyrus inoculum formed nodules "on most types of vetches." This statement may or may not have included intermountain milkvetches and sweetvetches. He also informed us that the Rhizobium in the Baptisia, Desmodium, Lespedeza, and Crotalaria inoculum tend to be less specific about which species they associate with. You may want to experiment with one - or a combination - of those inoculums as a "general inoculant."


Growing your own plants from seed is the most economical way to add natives to your home. Before you get started, one of the most important things to know about the seeds of wild plants is that many have built-in dormancy mechanisms that prevent the seed from germinating. In nature, this prevents a population of plants from germinating all at once, before killing frosts, or in times of drought. To propagate native plants, a gardener must break this dormancy before seed will grow.

Each species is different, so be sure to check the GERMINATION CODE listed on the website, in the catalog, or on your seed packet. Then, follow the GERMINATION INSTRUCTIONS prior to planting. Some species don't need any pre-treatment to germinate, but some species have dormancy mechanisms that must be broken before the seed will germinate. Some dormancy can be broken in a few minutes, but some species take months or even years.

Seed dormancy can be broken artificially by prolonged refrigeration of damp seed in the process of cold/moist STRATIFICATION. A less complicated approach is to let nature handle the stratifying through a dormant seeding, sowing seeds on the surface of a weed-free site in late fall or winter. Tucked safely beneath the snow, seeds will be conditioned by weathering to make germination possible in subsequent growing seasons.

To learn more, read our BLOG: How to Germinate Native Seeds

Dormant Bare Root Plants

We dig plants when they are dormant from our outdoor beds and ship them April-May and October. Some species go dormant in the summer and we can ship them July/August. We are among the few still employing this production method, which is labor intensive but plant-friendly. They arrive to you dormant, with little to no top-growth (bare-root), packed in peat moss. They should be planted as soon as possible. Unlike greenhouse-grown plants, bare-root plants can be planted during cold weather or anytime the soil is not frozen. A root photo is included with each species to illustrate the optimal depth and orientation. Planting instructions/care are also included with each order.

Download: Installing Your Bare-Root Plants

Potted Plants

3-packs and trays of 32, 38, or 50 plants leave our Midwest greenhouses based on species readiness (being well-rooted for transit) and order date; Spring shipping is typically early May through June, and Fall shipping is mid-August through September. Potted 3-packs and trays of 38 plugs are started from seed in the winter so are typically 3-4 months old when they ship. Trays of 32/50 plugs are usually overwintered so are 1 year old. Plant tray cells are approximately 2” wide x 5” deep in the trays of 38 and 50, and 2.5" wide x 3.5" deep in the 3-packs and trays of 32; ideal for deep-rooted natives. Full-color tags and planting & care instructions are included with each order.

Download: Planting and Care of Potted Plants

*PLEASE NOTE: we are a mail order nursery and have no retail facilities, but you may pick up your order if prior arrangements are made. Pick up orders are subject to 7.375% MN Sales Tax.

Shipping & Handling Charges

TOOL SHED and BOOKS have the shipping fee included in the cost of the item. In other words, they SHIP FREE!

Shipping Season

SEED, TOOLS and BOOKS are sent year-round. Most orders ship within a day or two upon receipt.


We ship using USPS, UPS and Spee Dee.