Friday, June 21, 2024


004 (2)You’re probably looking at my title and thinking that I spelled in error, the act of slumber after a heavy lunch. In my defense, naptime is usually when I think about how to react to all the purple knapweed growing on my farm this year. Just as I enjoyed an intense drool, dreaming of endless pristine pastures devoid of unsightly weeds, the annoying alarm clock of Mother Nature goes off and brings me back to the reality—weeds(also known as forage) are here to stay!

Poet, Phillip Pulfrey said it best:
I learn more about God
From weeds than from roses;
Resilience springing
Through the smallest chink of hope In the absolute of concrete….

My intimate relationship with this forage-weed is a lot like a marriage, it takes patience and compromise to work. Many folks abhor this matrimony and seek divorce by lethal injection with chemicals. I’m too darn stubborn to take this easy, costly route for I have an appreciation or affliction in working with this plant as a symbol of diversity and importance. In my way of thinking, God gave us this plant for a reason and I’m determined to find out why.

According to the late Newman Turner, this “herb” knapweed or hardheads, as he called them, is one of the few indicators of phosphate deficiency. He said, “The existence of knapweed is one of the few justifications for applying rock phosphate as well as manure and ground limestone.” Curious to me was his description of how far down the plant’s roots will go to tap subsoil phosphorus and thrive when other plants won’t. Since I have low phosphorus on many fields because of no grain importation or added soil amendments, this makes sense to me.

Ok, so it’s evident I have a problem. In addition to fertility, I have out-wintered on fields, scarring them up and compacting them which gives way to plants that can fill the void and have rolled out bales with knapweed plants in them. My friend Nathan also thinks the severe drought with long pasture recovery periods and the die back of other pasture species from last year is helping with the proliferation problem. I’m sure it’s a combination of many factors.

knapweed after grazing
Grazed Knapweed in the Bishopp pastures

The bigger question is what to do or not do against our holistic farm goals which direct us to like diversity, soil biology, water quality and wildlife. Can bigger picture thinking and land management be the right tools? I’m convinced if you study and observe the subtleties of nature, you’ll find the solution.

If you can accept the spotted, Russian or whatever knapweed species you have will always be around in some fashion depending on conditions, I think you can move forward in controlling the forage plant. Ian Mitchell-Innes coaxed me to move towards what I want by planning my grazing. He also liked that we have the most overlooked weed killer, frost and snow. I took this knowledge to heart.

LinktoSKArticleHere are a few control measures, minus chemical or biological remedies; I have tried with some success:

1) Teach your animals to eat it by learning animal behavior from Kathy Voth’s training regime.

2) Plan to graze an infested field when the plants are young and tender(4-6”) while getting enough animal impact to eat every plant or trample them.

3) Manure heavily or add compost or soil amendments so other plants out compete the weeds.

4) Graze more frequently avoiding long recovery periods >40 days and clip after each grazing period.

5) If the knapweed gets ahead of you, have the patience to let it flower (allowing bees to make you some awesome honey and grassland birds to nest) and then turn animals in to eat the blossoms and top leaves thereby stealing the plants ability to seed.

It’s number 5 that has me most interested. I’m not too old to forget the Bambi movie when Thumper the bunny rabbit was scolded by his mom for just eating the blossoms and came up with this famous quote, “Eating greens is a special treat, it makes long ears and great big feet. But it sure is awful stuff to eat.”

Here's the analysis of Knapweed as a forage.  Click for a larger view.
Here’s the analysis of Knapweed as a forage. Click for a larger view.

After witnessing the cows eating all the purple flowers and the top leaves when turned into a paddock, I decided to do a brix test on the plant. Turns out Thumper was right, the brix was twice that of the other plants in the field. I took it even further. I harvested them and sent them into the Dairy One Forage Lab. The technicians must have been scratching their heads as they tested them. In Jerry Brunetti’s honor, the sample (attached) came back indicating the plant parts were as good as pre-bud alfalfa with an excellent mineral profile. This was good stuff! Why would we want to kill it?

With the plant tops bitten off here in July and August, I went ahead and clipped the paddocks down so I would have quality stockpiled forage for fall and winter grazing before our frost in the first part of October. Taking a cue from Newman Turner’s chapter on making an herbal ley with a mower this now awesome forage-weed that sucked up phosphorus from the subsoil is chopped up and returned back to the soil biology to fertilize the growing sward. Cycle complete!

knapweed blossom eating before and after
Knapweed pasture, before and after grazing.

My long view of this purple knapweed problem and solution manifested itself while I was lingering in a field filled with busy pollinators. How would my decision effect more than me as the workers of humanity harvested pollen? Shouldn’t we weigh the control options very carefully because we have the ability to think with this big brain cell of ours?

I’m convinced if you work with nature on the same plane, you’ll find the answers you need. But it might take alittle nap to get you prepared for a change in mindset.

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Troy Bishopp
Troy Bishopp
Troy Bishopp, aka “The Grass Whisperer” is a seasoned grazier and grasslands advocate who owns, manages and linger-grazes at Bishopp Family Farm in Deansboro, NY with his understanding wife, daughters, grandchildren and parents. Their certified organic custom grazing operation raise dairy heifers, grass-finished beef and backgrounds feeder cattle on 180 acres of owned and leased pastures. Troy also mentors farmers on holistic land management for the Madison County Soil and Water Conservation District and the Upper Susquehanna Coalition as their regional grazing specialist. This award-winning free-lance writer, essayist and photographer maintains a website presence at


  1. This is such a timely (and informative) article for me as I have been fretting about an explosion of knapweed in what was a rotationally grazed sheep pasture until about two years ago when I got rid of the sheep to focus on raising pigs. Now the pasture is a custom-cut hay field. The sheep did an excellent job of keeping the knapweed confined to the southwest corner of the pasture, but since the sheep have gone, the knapweed has literally sprinted up the field in line with the prevailing wind.

    It’s time to get back into sheep and do some soil fertility management.

    Thank you for the excellent article.

  2. Troy, We have primarily spotted knapweed here in central ID and it occurs primarily on our dry land or spring flood ground. There is very little on the pivots as we keep the ‘desirable’ forage too competitive for knapweed to take a hold. We motivated our cattle to eat it within the first year or so we were out here simply through higher stock density grazing.

    Where we still have problems with it are the dry areas that only get grazed once a year. We can bite it off completely in June, but it is seeded out in August. Since we don’t mow anything due to all the rocks, clipping is not really an option.

    The indication of P deficiency was news to me so thanks for that tidbit.


    • I think that even though your once bitten plants seed out in August, you’re likely still making progress. Research has shown that the seed viability of once bitten plants is reduced by about 50%. If you can graze these plants while flowering, seed set is reduced by about 90%. It’s not a perfect solution, because knapweed produces so many seeds. But it’s a start.

  3. Troy’s comment “spotted, Russian or whatever knapweed species” refers to the taxonomic confusion around these species. All species in this genus come from Asia, and as they have spread through North America some have apparently hybridized. Even where they haven’t, it can be hard to tell the species apart. To my eye we have two distinct types in the Northeast:
    Spotted knapweed (Centaurea stoebe, also known as C. maculosa) has fine pale-green leaves, and small pink-purple flowers.This is not the species pictured. Spotted knapweed favors roadsides, sand, gravel pits, and other droughty sites, and is not typically found in mesic pastures. It seems to be expanding rapidly in the Northeast, and is wildly abundant and seriously invasive in parts of western North America.

    The species pictured probably would best be referred to as “meadow knapweed”. I have not been able to definitively identify it, and every year the taxonomy seems to change. An identified hybrid, C. xMoncktonii, (C. nigra x C. jacea?) seems to be much like this plant, while the resumed parents of the hybrid are just a bit different.

    Our experience grazing meadow knapweed is much like Troy’s: cows and sheep eat it without prompting, so it doesn’t take over rotationally-grazed pastures. Where we have only cut one cut of hay for a couple of years, it can expand. One area where it is abundant also has a large patch of milkweed, so we sometimes leave this area for the insects. Spotted knapweed is less substantial, but as Kathy has shown, livestock will eat it also.

    Bruce Howlett, Putney VT

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