One of my constant refrains is “Permaculture is a decision making tool for arriving at regenerative solutions.” Here I’m going to show how permaculture can help create strategies for deciding what cover crops to use. In permaculture, we’re always looking for potent leverage points, and soil-building is a big one. If we create fertile, water-absorbing, biology-rich soil, a lot of higher-level problems—things like insect damage, low nutrition, poor growth, and excess water use—all go away. And cover cropping, which is the use of specific plants to add organic matter and nutrients, is a great way to build soil. I use other methods, such as composting and nulching, but there’s something about having living roots in the soil that makes cover cropping extra effective. That thick network of roots is constantly exuding sugars and other microbe food, creating a life-rich rhizosphere that pumps nutrients into plants and builds a lush habitat for mycelium and other beneficial organisms.
I’m going to use cover cropping to illustrate how permaculture decision-making works. How do we design a cover cropping program? Good design has three major components: setting a goal, developing strategies, and choosing techniques. First, we already have our goal: We want to build our soil’s fertility, organic matter, and tilth. There are many strategies for reaching this goal. (A strategy is simply a plan, or, as management consultant Henry Mintzberg puts it in my favorite definition, a strategy is a pattern in a stream of decisions) Different strategies for soil building include composting, sheet mulching, chemical fertilizers, organic fertilizers, cover cropping, and several more. It may seem like those are techniques rather than strategies, but I think of them as strategies because there are so many different ways of doing each. Do any two people build a compost pile in the same way? And we have many different kinds of cover crops, and a host of ways to use them. That’s why I think of each of those as a strategy: Just because we’ve arrived at cover cropping as a way to build soil, we’re not done with making decisions. There’s a “lower” or more fine-grained level that we need to make some choices about. We need to choose the specific variety of cover crop, how and when we will plant, and how we will get that cover crop into the soil, such as by tilling, chop-and-drop, or harvesting and composting it. So we need to have some criteria in mind to help us make those decisions. That’s one of permaculture’s strong points: It gives us tools that remove a lot of uncertainty from making decisions. That lets us rest in the near-certainty that we’ve made appropriate choices.
To start that decision-making process, we first gather up information about cover crops—we make lists. The first obvious list to make is simply a compilation of all the varieties of cover crops that can grow in our conditions. A little Googling will get us there. One of my top sources of cover crop information is Peaceful Valley Farm Supply (https://www.groworganic.com). They ‘ve got a huge assortment. But a simply list of cover crop species doesn’t get us very far. We need to break it down into some categories, because we can’t just plant any old cover crop; every soil has specific needs and conditions. Fortuitously, the drop-down menu on cover crops at the above link has already done some category-making for us. They’ve divided cover crops into fall-planted or cool-season types, warm-season types, and year-round varieties. These categories give us a handy machete to begin chopping our way through the cover-crop thicket.
What other categories will be useful in choosing cover crops? Another big dividing line is between plants that fix nitrogen and those that don’t. Nitrogen-fixing cover crops are varieties that have a symbiotic relationship with specialized bacteria that can take gaseous nitrogen from the air, which plants can’t use, and transform it into nitrate, nitrite, or ammonia, which plants can take up as fertilizer. Non-nitrogen fixing cover crops are important too. They build biomass and add carbon to the soil, which feeds beneficial soil organisms, helps retain moisture, lightens and fluffs heavy soil and—oh, right—alleviates climate change by pumping carbon dioxide out of the air and storing the carbon in the soil. Most cover crop blends contain a mix of N-fixers and non-N-fixers.
A third division, near and dear to permaculturists, is that between annual and perennial cover crops. Annuals are great if we’re going to till in the cover crop or follow the cover crop with something else. But there’s a role for perennials, too, in paths or between rows of production crops, or as a constant biomass source. In a perfect world, all gardeners and farmers would be generating their own fertility on-site, not importing it from somewhere else that might be impoverished by the constant drain of organic matter. Ecological garden guru John Jeavons says that we should be dedicating roughly four to six times the area of our food garden to fertility crops to cover what we withdraw from harvesting. Before the fossil fuel era, most farms allotted more land for fertility production in the form of pasture for generating animal manure than they did for food production.
We could come up with other categories, such as soil preference (clay, silt, sand), frost hardiness, and so forth, but the three I’ve outlined above are the ones I use most often. Those categories create a two-by-two-by-two matrix or three-dimensional chart that really helps to zero in on the right choices. Let’s build that chart.
USDA Cover Crops
Here’s a table of over 100 useful cover crops, edited from a USDA list at http://plants.usda.gov/java/coverCrops?sort=comname
Click to download the table below as a PDF
|Scientific Name||Common Name||Plant Family|
|Amaranthus caudatus||foxtail amaranth||Amaranthaceae – Amaranth family|
|Amaranthus cruentus||red amaranth||Amaranthaceae – Amaranth family|
|Amaranthus hybridus × hypochondriacus||Plainsman amaranth||Amaranthaceae – Amaranth family|
|Amaranthus hypochondriacus||Prince-of-Wales feather||Amaranthaceae – Amaranth family|
|Arachis glabrata||rhizoma peanut||Fabaceae – Pea family|
|Arachis hypogaea||peanut||Fabaceae – Pea family|
|Avena sativa||common oat||Poaceae – Grass family|
|Avena strigosa||black oats||Poaceae – Grass family|
|Beta vulgaris||common beet||Chenopodiaceae – Goosefoot family|
|Beta vulgaris ssp. cicla||chard||Chenopodiaceae – Goosefoot family|
|Brachiaria ramosa||signalgrass||Poaceae – Grass family|
|Brassica hirta||white mustard||Brassicaceae – Mustard family|
|Brassica juncea||brown mustard||Brassicaceae – Mustard family|
|Brassica napus var. napus||rape||Brassicaceae – Mustard family|
|Brassica napus var. pabularia||Siberian kale||Brassicaceae – Mustard family|
|Brassica nigra||black mustard||Brassicaceae – Mustard family|
|Brassica rapa var. rapa||field mustard||Brassicaceae – Mustard family|
|Bromus hordeaceus||soft brome||Poaceae – Grass family|
|Cajanus cajan||pigeonpea||Fabaceae – Pea family|
|Camelina sativa||false flax||Brassicaceae – Mustard family|
|Canavalia ensiformis||jack bean||Fabaceae – Pea family|
|Carthamus tinctorius||safflower||Asteraceae – Aster family|
|Chenopodium quinoa||quinoa||Chenopodiaceae – Goosefoot family|
|Cicer arietinum||chick pea||Fabaceae – Pea family|
|Cichorium intybus||chicory||Asteraceae – Aster family|
|Crotalaria juncea||sunn hemp||Fabaceae – Pea family|
|Cucurbita||gourd||Cucurbitaceae – Cucumber family|
|Cyamopsis tetragonoloba||guar||Fabaceae – Pea family|
|Daucus carota var. sativus||carrot||Apiaceae – Carrot family|
|Echinochloa crus-galli||Barnyard grass||Poaceae – Grass family|
|Elymus hoffmannii||RS wheatgrass||Poaceae – Grass family|
|Elymus trachycaulus||slender wheatgrass||Poaceae – Grass family|
|Eragrostis tef||teff||Poaceae – Grass family|
|Eruca vesicaria ssp. sativa||rocketsalad||Brassicaceae – Mustard family|
|Fagopyrum esculentum||buckwheat||Polygonaceae – Buckwheat family|
|Glycine max||soybean||Fabaceae – Pea family|
|Helianthus annuus||common sunflower||Asteraceae – Aster family|
|Hordeum||barley||Poaceae – Grass family|
|Hordeum pusillum||little barley||Poaceae – Grass family|
|Hordeum vulgare||common barley||Poaceae – Grass family|
|Indigofera hirsuta||hairy indigo||Fabaceae – Pea family|
|Lablab purpureus||hyacinth bean||Fabaceae – Pea family|
|Lathyrus sativus||white pea||Fabaceae – Pea family|
|Lathyrus sylvestris||flat pea||Fabaceae – Pea family|
|Lens culinaris||lentil||Fabaceae – Pea family|
|Lespedeza capitata||roundhead lespedeza||Fabaceae – Pea family|
|Linum usitatissimum||common flax||Linaceae – Flax family|
|Lolium perenne ssp. multiflorum||Italian ryegrass||Poaceae – Grass family|
|Lolium rigidum||Wimmera ryegrass||Poaceae – Grass family|
|Lolium temulentum||Darnel ryegrass||Poaceae – Grass family|
|Lotus corniculatus||bird’s-foot trefoil||Fabaceae – Pea family|
|Lotus tenuis||narrowleaf trefoil||Fabaceae – Pea family|
|Lupinus||lupine||Fabaceae – Pea family|
|Lupinus albus||white lupine||Fabaceae – Pea family|
|Lupinus angustifolius||narrowleaf lupine||Fabaceae – Pea family|
|Medicago littoralis||water medick||Fabaceae – Pea family|
|Medicago lupulina||black medick||Fabaceae – Pea family|
|Medicago polymorpha||Bur clover||Fabaceae – Pea family|
|Medicago rugosa||gama medic||Fabaceae – Pea family|
|Medicago sativa||alfalfa||Fabaceae – Pea family|
|Medicago scutellata||snail medick||Fabaceae – Pea family|
|Medicago truncatula||Barrel clover||Fabaceae – Pea family|
|Melilotus alba||white sweet clover||Fabaceae – Pea family|
|Melilotus officinalis||sweetclover||Fabaceae – Pea family|
|Mucuna pruriens||velvet bean||Fabaceae – Pea family|
|Onobrychis viciifolia||sainfoin||Fabaceae – Pea family|
|Panicum miliaceum||proso millet||Poaceae – Grass family|
|Pennisetum glaucum||pearl millet||Poaceae – Grass family|
|Phacelia tanacetifolia||lacy phacelia||Hydrophyllaceae – Waterleaf family|
|Pisum sativum||garden pea||Fabaceae – Pea family|
|Poa pratensis||Kentucky bluegrass||Poaceae – Grass family|
|Psathyrostachys juncea||Russian wild rye||Poaceae – Grass family|
|Puccinellia distans||weeping alkaligrass||Poaceae – Grass family|
|Puccinellia nuttalliana||Nuttall’s alkaligrass||Poaceae – Grass family|
|Raphanus sativus||cultivated radish||Brassicaceae – Mustard family|
|Secale cereale||cereal rye||Poaceae – Grass family|
|Sesbania bispinosa||dunchi fiber||Fabaceae – Pea family|
|Sesbania herbacea||bigpod sesbania||Fabaceae – Pea family|
|Sesbania sesban||Egyptian river hemp||Fabaceae – Pea family|
|Setaria italica||foxtail millet||Poaceae – Grass family|
|Sinapis alba||white mustard||Brassicaceae – Mustard family|
|Sorghum bicolor||sorghum||Poaceae – Grass family|
|Sorghum bicolor × S. bicolor var. sudanense||Sudex (Sorghum-sudangrass)||Poaceae – Grass family|
|Sorghum bicolor var. bicolor × bicolor var. sudanense||Sudex||Poaceae – Grass family|
|Spinacia oleracea||spinach||Chenopodiaceae – Goosefoot family|
|Thinopyrum intermedium||intermediate wheatgrass||Poaceae – Grass family|
|Thinopyrum ponticum||tall wheatgrass||Poaceae – Grass family|
|Trifolium alexandrinum||Egyptian clover||Fabaceae – Pea family|
|Trifolium ambiguum||Kura clover||Fabaceae – Pea family|
|Trifolium fragiferum||strawberry clover||Fabaceae – Pea family|
|Trifolium hirtum||rose clover||Fabaceae – Pea family|
|Trifolium hybridum||alsike clover||Fabaceae – Pea family|
|Trifolium incarnatum||crimson clover||Fabaceae – Pea family|
|Trifolium pratense||red clover||Fabaceae – Pea family|
|Trifolium repens||white clover||Fabaceae – Pea family|
|Trifolium subterraneum||subterranean clover||Fabaceae – Pea family|
|Trifolium vesiculosum||arrowleaf clover||Fabaceae – Pea family|
|Trigonella||fenugreek||Fabaceae – Pea family|
|Triticosecale rimpaui||triticale||Poaceae – Grass family|
|Triticum aestivum||common wheat||Poaceae – Grass family|
|Urochloa ramosa||browntop millet||Poaceae – Grass family|
|Vicia atropurpurea||purple vetch||Fabaceae – Pea family|
|Vicia benghalensis||purple vetch||Fabaceae – Pea family|
|Vicia faba||fava bean||Fabaceae – Pea family|
|Vicia grandiflora||large yellow vetch||Fabaceae – Pea family|
|Vicia sativa||garden vetch||Fabaceae – Pea family|
|Vicia villosa||winter vetch||Fabaceae – Pea family|
|Vigna radiata||mung bean||Fabaceae – Pea family|
|Vigna unguiculata||cowpea||Fabaceae – Pea family|
|Vulpia myuros||annual fescue||Poaceae – Grass family|
|Zea mays||corn||Poaceae – Grass family|
Next we need to organize these by dividing them up into our matrix. We’ve got 3 categories and two choices in each category.
- N or B: nitrogen-fixer or biomass accumulator;
- W or C: warm season or cool season; and
- A or P: annual or perennial.
Two choices in each of three categories makes eight possible combinations in our matrix, which I will label like this:
- NCA (N-fixer, cool season, annual)
- NCP (N-fixer, cool season, perennial)
- NWA (N-fixer, warm season, annual)
- NWP (N-fixer, warm season, perennial)
- BCA (Biomass, cool season, annual)
- BCP (Biomass, cool season, perennial)
- BWA (Biomass, warm season, annual
- BWP (Biomass, warm season, perennial).
We can organize those eight combinations in a matrix:
And now we need to split our cover crop variety list into those eight categories. I’ve created a table, below, with the cover crops divided into annuals, perennials, N-fixers, and biomass plants, but having spent more time on this post than I intended to, I haven’t divided them into warm and cool weather crops. Sample cool weather cover crops are fava beans, winter wheat, and vetch. Warm weather cover crops include alfalfa, sudan grass, and buckwheat. Interested readers can use the catalog and tables from Peaceful Valley Farm Supply or other sources on the web to create the remaining categories. Or maybe I’ll get around to it someday.
Cover Crops By Function
Click to download the table below as a PDF
|N- fixer, Annual||N-Fixer, perennial||Biomass, annual||Biomass perennial|
|arrowleaf clover||alfalfa||annual fescue||browntop millet|
|chick pea||alsike clover||barley||chicory|
|cowpea||bigpod sesbania||black mustard||Intermediate wheatgrass|
|crimson clover||bird’s-foot trefoil||black oats||Italian ryegrass|
|Egyptian clover||black medic||buckwheat||Kentucky bluegrass|
|Egyptian river hemp||bur clover||carrot||Nuttall’s alkaligrass|
|Fava bean||Flat pea||ceral rye|
|gama medic||Lablab bean||Chickpea|
|garden pea||lupine||common barley|
|garden vetch||narrowleaf lupine||common beet|
|guar||narrowleaf trefoil||common flax|
|hairy indigo||red clover||common oat|
|hyacinth bean||sesbania||common sunflower|
|Kura clover||sweetclover||common wheat|
|large yellow vetch||white clover||corn|
|lentil||white sweet clover||cultivated radish|
|mung bean||Darnel ryegrass|
|pigeon pea||Field mustard|
|purple vetch||foxtail amaranth|
|rhizoma peanut||foxtail millet|
|roundhead lespedeza||lacy phacelia|
|snail medic||pearl millet|
|strawberry clover||plainsman amaranth|
|subterranean clover||Prince-of-Wales feather|
|sunn hemp||proso millet|
|white lupine||red amaranth|
|winter vetch||RS wheatgrass|
|Russian wild rye|
I hope you find this useful. Permaculture really can be a great decision-making tool.
Sheri Cline says
Many years ago as a child, I spent 2 weeks in the Palomar Mountains of California. The trees had a “black fungus” on them and I decided to write my Dear Uncle Jim a letter about what I had seen and to see if he could tell me what it was since my Palomar camp guides had no idea. My Uncle Jim “Cook” sent me a ton of materials and I’ll always remember my mother’s response; “He didn’t need to write a “Thesis” on it!” My Uncle changed my world with his “Thesis”. He took the time to collect information that he was passionate about and he shared it with me. To this day his passion for this earth has never faltered and I love him with all my heart for his caring. Your a special blessing and soul Toby Hemenway. I hope and I pray that your passion stays strong and connected. What an excellent post!
Elizabeth Nobbe says
I share Sheri’s appreciation for your wonderful way of teaching patterns, making a wealth of information applicable and life enriching.
And I love the definition of ‘strategy.’ You made that word less daunting.
Thank you, Toby Hemenway.
Bill Wilson says
Wonderful Toby. Very nicely organized. What a gift. Thank you.
Thank you so much for this.
Last year was my first year having my own yard or a garden. In an attempt to try to implement some permaculture principles that I really don’t know much about I had read to plant cover crops and so I planted white clover all over all my herb spirals and all keyhole gardens and between them. I realise now I should maybe not have planted them everywhere where I wanted veggies etc to grow too. How do I prevent the clover from coming back in those areas or what can I do so it doesn’t take over so much? It did help with moisture and weed control but was really aggressive and crowded out some of the vegetables. Any suggestions? Thank you!
We did the same thing with red clover & are wondering the same as you now … we’d love suggestions too …. this is what we are trying this year as an experiment.
1. Pulling out & clearing areas for veggies &
cutting clover short, thinking that roots will be less deep & allow veggies some space.
2. Laying strips or patches of cardboard down around veggies to keep clover back a little…. but this is a bit of a problem as it seems to attract slugs
Our strawberries seem happy to grow interspersed with the clover … extra big & more strawberries… just a little more looking through the clover to find the fruit.
Mary Rose Noll HIlkemeyer says
i am happy with the way clover tends to keep the soil softer where my strawberries grow. I too am experiementing with permaculture gardening as i am wanting to keep the soil rich for the gardens i grow.
Thank you for your sharing.