Invest in Cover Crops This Fall, and Save Money in Fertilizers Next Spring!

By on July 26, 2011

I surround myself with Peaceful Valley co-workers from 9-5 and farmer friends after hours. With August just around the corner, all I hear about are cover crops or green manure and how wonderful they are.

This year I actually stopped and asked for clarification about how legume cover crops “fix pounds of nitrogen”.

Fix nitrogen? If you add an organic, nitrogen-rich fertilizer to promote vegetative growth, you already know how critical nitrogen is to your garden. Now imagine planting an inoculated legume seed this fall, letting it grow all winter, and tilling it under in the spring to achieve the same “fertilization”. Pretty neat!

Pounds of nitrogen? Just what are we measuring and comparing? We’ve taken care of the crop sampling and calculating for you!

On our Cover Crops page there is a left sidebar that shows you different capabilities of our cover crops. You can sort them by “easily established” or “good weed competition”, for instance.

You can also sort for “fixes nitrogen”. In each product description we tell you how much nitrogen that particular cover crop fixes.

You can go to the store and buy a 6 lb. box of powdered fertilizer. It of course weighs 6 lbs. If you grow cover crop, we tell you the weight of the dried nitrogen content. So if you plant a cover crop like our Premium Soil Builder Mix (which fixes 20 lbs. of nitrogen per 3,000 sq. ft.) you’ll reap the equivalent benefit of 20 lbs. of powdered 100% nitrogen fertilizer.

My 50’ x 60’ garden example: The Premium Soil Builder Mix can fix up to 20 lbs. of nitrogen in my 3,000 sq. ft. garden. All I need is 15 lbs. of inoculated Premium Soil Builder Mix (15 lbs of SCM120 is $22.35, plus $7.99 Garden Combination Inoculant = $30.34). If I inoculate and plant this fall and till into my soil in the spring, I will enjoy the high levels of nitrogen in my garden as well as other benefits that come from increased organic matter and microbial life.

Alternatively, in the spring I could buy 500 lbs. (10 bags) of Nutri-Rich 4-3-2 fertilizer (one of the best values with 4% nitrogen) for over $125 to achieve the same nitrogen payout!

So in the end I will definitely invest $30.34 in Cover Crops this fall for my large, 3,000 sq. ft. garden and I’ll save at least $125 in fertilizers come spring.

  Comments (26)


what if we planted the cover crop seeds but did not inoculate them first? Will we stil lhave the nitrogen fixing? When is the right time to till it in? Thanks.

Posted by judith wigren-slack on Mar. 03, 2012 at 10:21:01 AM

Judith. The rhizobacteria in the inoculant help to “fix” the nitrogen in the soil. Without the bacterial boost from the inoculant you will not end up with as much nitrogen in you soil. Till in the cover crop when half of it has bloomed.

Posted by on Oct. 17, 2012 at 4:54:32 PM



I look up SCM121 at  It states “Seed at 3-5 lb/1000 sq ft, ....”  I take it means 5 lbs of seeds can be grown on a 1000 sq ft garden. 

However, in the More Information section of the web page, I click on “Product Use Instructions: PVFS Premium Soil Builder Mix - Raw Seed (Lb) Instructions” and get a pdf file “Cover Crops, Erosion Mixes & Pastures—Planting & Growing Guide.”  In the Fertility section, it says “Rates to use should
be determined by a soil analysis, but generally ... home garden rates of 1 pound per 2-10 sq. ft.”  That means 5 lbs of seeds can be grown on only 50 sq ft garden, which is much less than 1000 sq ft said on the web page. 

I probably miss something on the seed usage.  Would you please help clarify how much seeds should be used?  Thanks.

Posted by Thuan Tran on Nov. 05, 2012 at 8:42:02 PM


How are you calculating how much nitrogen the cover crop creates?

Thank you,

Posted by Kay on Dec. 03, 2012 at 7:27:13 AM

Kay,  Good question! She was using Premium Soil Builder Mix which fixes 290 lb. of nitrogen per acre, and she calculated that her 3,000 sq ft garden was .068 of an acre, resulting in 20 lb for her garden.

Or did you want to know how we got the original figure for Premium Soil Builder Mix?

Posted by on Dec. 03, 2012 at 12:50:27 PM


Do you know how the 290lbs per acre was calculated?  The reason I ask is I am looking for ways to market cover crops to producers in southern Michigan. This work is done through a Nitrate reduction grant to improve the water quality of Lake Erie.

Posted by Kay on Dec. 06, 2012 at 12:02:57 PM


Can I still plant the cover crop now that it is almost January?

Posted by Brook on Dec. 29, 2012 at 9:15:45 PM

Kay, The calculation comes from the farmers raising the cover crops.

Posted by on Dec. 29, 2012 at 10:46:47 PM

Brook, Cover crops are usually planted in September and October, well before the first frost. You can also do spring planting if you live in a coastal or cool summer area, but plant at the same time you would sow peas, and plan to let them grow throughout the summer.

Posted by on Dec. 29, 2012 at 10:51:49 PM


When to plant?  We did not plant a cover crop in the fall because the garden is still in production up until frost.  If we wait until spring, it’s a problem because it’s always too wet to work our heavy soil.  Is it possible to plant a cover crop in Feb or March (when it’s way below freezing at night) if the soil is workable, and have it start to grow when it warms up?  Does that hurt the bacterial too much?
  Secondly, are there cover crops that do not tie up your garden for the full summer season?  How about buckwheat, I’ve heard that’s good at killing weeds.
  Thank you.

Posted by Athena on Jan. 21, 2013 at 10:59:50 AM


Athena, Typically people plant in early fall, and either rotate the area that they cover crop, or sacrifice some late harvest. The relationship between air temperature and soil temperature is complicated, but use a soil thermometer to check It is very unlikely that any cover crop seed would germinate when the night temperatures are below freezing. For a fast, warm season cover crop that shades out weeds, buckwheat would be a good choice. It germinates when the soil is 45F-105F

Posted by Charlotte, Peaceful Valley on Jan. 22, 2013 at 5:22:25 PM

Thuan Tran, The More Information section you are reading and referring to is in the Fertility section of the “Cover Crops, Erosion Mixes & Pastures—Planting & Growing Guide.” It refers to rates for application of compost, not the cover crop seed.

Posted by on Jan. 30, 2013 at 5:50:21 PM


I have two small beds that I wanted to “rest” till fall. They still have broccoli and cabbage in them and I want to wait till they are no longer producing to plant the cover crop. I am on the coast in Central Florida. Can I plant the cover crop in mid May?

Posted by heidi on Apr. 17, 2013 at 7:48:10 AM

Heidi, For a summer/warm weather cover crop use our Summer Soil Builder Mix It needs a Cowpea Inoculant Easy to follow demo on how to mix the cover crop seed and the inoculant is in our video here

Posted by on Apr. 17, 2013 at 10:39:48 AM


I understand non chlorinated water may be used to inoculate legumes. I was not aware chlorine is often used to treat public drinking water. Is this chlorine enough to kill the inoculant? If so, can the water be set out a day to remove the chlorine?

I think the proper use of regular drinking water should be made more clear in inoculant instructions. When I think of chlorine in water I think of swimming pools. I do not drink milk which is suggested as an alternative to water. Thank you.

Posted by Erich on Oct. 22, 2013 at 7:32:42 PM

Yes, you can set the tap water out for 24 hours to allow the chlorine to dissipate. If you use a wide bowl the better the dissipation. The innoculant is a living microorganism so chlorine will have an adverse effect.

Posted by on Dec. 21, 2013 at 9:41:04 AM


How long does it take for the cover crop to mature before you can till it into the soil?

Posted by Elissa on Dec. 30, 2013 at 8:01:46 PM

Hello Ellssa,

It depends on the seed you choose. For the Premium Soil Builder it takes on average from October-March about 5 months.

Posted by on Jan. 15, 2014 at 10:04:14 AM


I am on the coast of California with very sandy soil, and want to get a cover crop for my garden.  Was thinking of getting the premium soil builder for the garden, but is there something you would recommend to help build up my poor draining, sandy soil?

Posted by Elaine on Oct. 05, 2014 at 12:12:50 PM

The Premium Soil Builder Mix is a fantastic mix for a cover crop. The mix will add nitrogen to your soil through nitrogen fixing of the legumes and when you chop it and till it under in the spring, loads of organic matter will be added to your soil. Now keep in mind one season will not reverse the problems in your soil. Keep it up, year after year. Your soil will benefit and so will you, with all the great veggies you will grow.

If you have space, there are also cover crops that can be planted in the summer as well. Summer Soil Builder Mix comes to mind.

Posted by Suzanne at Peaceful Valley on Oct. 07, 2014 at 2:38:51 PM


My beds are sleeping under some rice straw now.I want to provide for early pollinators with a no till crop.Would the soil builder mix ,planted now(January) suppress weeds,provide the poilinators but also not have to be tilled for spring planting?I don’t want to till,just build up soil and tamper weed growth .thx

Posted by June on Jan. 24, 2015 at 4:07:49 PM

I can’t fully answer this question since I don’t know where your garden lives. Typically the soil builder mix is planted in the fall and is knocked down when the plants start to bloom. If you don’t want to till it in, you should still knock it down by cutting (I use a weed eater) since the plant will start to draw all those nutrients stored in the roots to feed the top growth.

Posted by Suzanne at Peaceful Valley on Jan. 30, 2015 at 4:58:39 PM


I live in a zone 4b in Southcentral Alaska. I have a 48x20 garden I would like to cover crop to amend my silty-clay soil and to add nitrogen for the spring. It is now July 31st can I grow my cover crop until the end of September, till it under and plant garlic?

Posted by charlene on Jul. 31, 2015 at 11:26:19 PM

We recommend planting garlic 2 weeks before the first frost. Not sure about your area, but September might be too late to plant garlic. You probably can plant your cover crop now and let it grow until you are ready to plant your garlic. Just make sure you choose a hard neck variety for cold regions and that you plant it 2 weeks before the first frost and that you much it heavily.

Posted by Suzanne at Peaceful Valley on Aug. 04, 2015 at 10:17:48 AM


I am in SW Michigan can I use this premium soil builder mix?? zone 6… if not what mix would you have that we could grow in fall and then turn in spring?

Posted by marie evans on Jun. 19, 2016 at 9:03:39 AM

Marie, You can try the cold zone soil builder mix, It will survive colder temps. If you want to try the premium soil builder mix, just plant it early enough so the plants have time to get established. They will get knocked back in the winter, but as long as your soil does not freeze, they should come back in the spring.

Posted by Suzanne at on Jun. 21, 2016 at 10:19:19 AM

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