Category Archives: cover crops

Cover Crops

by Julia Frisbie

posted August 19, 2021

Mid to late August is the time to plant overwintering cover crops. Also known as living mulches and green manures, the goal when planting a cover crop is to cover the soil between main crops. By now you know that I’m really into mulching, and always try to keep my soil covered. Cover crops have lots of benefits, especially over the winter season:

They prevent erosion.
They suppress weeds (like bittercress, the winter germination specialist).
They feed the “underground herd” (a term borrowed from Gabe Brown’s book Dirt to Soil) of microbes and mycorrhizae by keeping living roots in the ground year-round.
They provide habitat and food for above-ground critters who share space with us in winter.
They add organic matter to the soil.

As if all this weren’t enough of a gift, many species offer additional benefits. Some are insectaries. Some can help break up compacted soil (especially brassicas, like mustards and daikon radishes). Some are really amazing dynamic accumulators, which means they’re especially efficient at building biomass. Many of the most popular cover crop species can add nitrogen to the soil (like legumes). Cover crops teach us that each individual has a role to play in supporting the health of the whole.

To compare common cover crop species, check out Gaia’s Garden by Toby Hemenway. It’s another book that I finally purchased after borrowing from our local library three times… so I know the library has it! I love the author’s way of describing plant functions in tables. Here’s the one on winter cover crops:

So, what works best on Fidalgo island? I haven’t experimented with grasses and grains, but I’ve tried several types of clover (all clovers fix nitrogen!) and lots of wildflowers. Here are a few favorites.

Crimson clover. It’s fuzzy and soft with lovely, deep magenta booms. The only downside is that it doesn’t suppress weeds as readily as other clovers because it’s tall and skinny rather than spreading.
Microclover. It’s adorable and very low-growing, but it takes a long time to establish because it’s so small.
New Zealand White clover. This is my clover of choice for weed suppression. It out-competes weeds and becomes a perennial, standing up to foot traffic in my yard year after year.
Phacelia. Its common name is “bees’ friend” for a reason. It can grow four feet tall and gives me a rash when I brush against it, so I don’t plant it next to paths. This plant is an annual, but if you let it go to seed once, you’ll have it forever.
Poppies. I love looking at a sea of bright color. They require so little care, and seed is so cheap, that if you have a big blank spot in your yard you have nothing to lose by throwing poppy seeds at it. I’ve grown both Eschscholzia californica and Papaver rhoeas with good success. Like phacelia, poppies are annuals, but they reseed themselves freely.

I’d encourage you to plant as diverse a cover crop mix as you can stand to look at, because different species fill different ecological niches. For example, in my last article I noted that Jean-Martin Fortier of The Market Gardener plants an oat/pea mix as green manure in late August and early September. Peas fix the nitrogen, but can be a bit slow to start. Oats grow quickly to suppress weeds, creating a perfect environment for the peas to do their thing. These two offer a greater benefit together than they do apart. Gabe Brown takes it farther by planting dozens of species at once in the same place. Cover crops teach us that the whole can be greater than the sum of its parts.

Cover crops can enrich existing garden beds, but they can also be used to help prepare new ones. Fall is the best time to start new garden beds, so if you’re thinking of sheet mulching your grass into oblivion, now is the time to start planning. A lush cover crop is a wonderful way to tuck all your new compost/soil into place over the winter months.

Whatever you choose, mix the seeds together in a substrate like sand before broadcasting onto damp soil and tamping down. Then, just let nature do its thing. Some, like the clover, will germinate right away. Some, like the poppies, will wait until spring to get started. Not every plant will thrive in every spot… but by sowing a diverse mix, you will have hedged against some of them failing, so you’ll still end up with your soil covered and enriched over the winter months. Cover crops teach us that we can’t afford monocultures. Variety is protective against an unknowable future.

A Garden Homemaker: Lupine

by Julia Frisbie

posted June 27, 2021

It’s lupine season! This plant will always remind me of the happy summer weeks I spent in the mountains of northeastern Oregon as a child. I love seeing her by the roadside. I held her purple/blue spires in my arms on my wedding day. I’ve slipped her seed pods into my pockets for years, and like Ms. Rumphius in a favorite children’s book, scattered them when we found a place to call our own.

Like all legumes, she works with a symbiotic bacteria to fix nitrogen in the soil, enough to meet her own needs and also share with neighbors. She has a long taproot that breaks up compacted earth. She can collect moisture from the air, with leaves shaped like tiny hands that cradle a single dewdrop in their palms. She makes a huge mass of greenery each year, only to lay it all down on the ground after the first frost, protecting soil from winter runoff and feeding the microbial community below. Her nectar feeds bees and her seeds feed birds.

In other words, she is a homemaker, showing up to disrupted or neglected soil and creating beauty and fertility. She can make something from almost nothing.

I’ve invited lupine to my yard as an early succession plant. Right after I mulched over most of the lawn in our front yard, I scattered lupine seeds. For several years, a long hedge of lupine has lived alongside what’s left of the grass:

As I add longer-lived plants to the landscape, I’m gradually pruning/removing the lupine to make space. Many perennials take years to get established and come into their own, and lupine fills out the garden around them while they bide their time. Lupine self-sows readily, but she’s easy enough to remove, so as long as I’m paying attention she doesn’t choke other plants out. Here’s a first-year peony growing in the shelter of lupine:

I often call on lupine as a companion plant for young trees. Planting a nitrogen-fixer in the same hole as a baby tree is something my partner learned while volunteering at the Bullock’s Permaculture Homestead on Orcas Island. I dig up the lupine, taproot and all, and plop it right in there among the roots of the sapling. Abundant nitrogen allows the sapling to make lots of new greenery (and, I think, helps it feel less lonely and more at home). Here’s a little plum tree hiding from deer among the lupine:

You can sow lupine any time of year, but my favorite way is to take my cue from the plant herself, and spread her seeds right after they pop from her wonderful fuzzy seed pods in July. I cut the seed heads when they get dry and begin to rattle, and then I pile them into a washtub basin and invite my four-year-old to thresh them by jumping up and down on the pods until the seeds are released. Then we winnow by pouring seeds back and forth between buckets in the middle of our street on a windy day. This ritual yields a quart of seed from our couple dozen plants. If you’d like some for your garden, I’d be delighted to give them to you. That’s part of how I respond with reciprocity to lupine: by finding good homes for her seeds. They’ll be part of Transition Fidalgo’s seed bank. Email info@transitionfidalgo.org to get connected!

Monoculture lawns to Polyculture garden beds

By Julia Frisbie

posted May 6, 2021

We buried our lawn five years ago under a layer of cardboard and then compost, planted a living mulch the first season, and have been mulching with arborist chips and rotating poultry through it, and growing a happy riot of annuals and perennials in it ever since. You can see the difference in this picture between our backyard soil (front right) and the soil in the adjacent easement (back left), but now after a soil test we have quantitative data. Using this data to estimate how much carbon we’ve sequestered was the most fun I’ve had with math in months!

We sent in two soil tests to the University of Massachusetts, with the city easement functioning as a control because it’s all in grass, and our yard was all in grass before we moved in five years ago. (It would have been better if I’d tested the same spot 5 years ago, but I didn’t, so the easement is our best point of reference for a comparison.) The backyard had 22.4% soil organic matter (measured by LOI, or “lost on incineration”… basically, how much of its mass can burn up) and the easement soil had 10.6%. So the backyard’s soil is 11.8 percentage points higher than our control plot.

I based my calculations on research by R. Lal of Ohio State University’s Carbon Management and Sequestration Center. His article “Abating climate change and feeding the world through soil carbon sequestration” was published 2013 in an anthology called Soil as World Heritage. Lal estimates that 21 tons of carbon are sequestered per additional 1% of soil organic matter per hectare.

Our backyard measures 74 feet x 40 feet, which is 2,960 square feet. There are 107,639 square feet in one hectare, so our backyard = 0.0275 hectares. Multiply 21 tons by 0.0275 = 0.5775 tons of carbon sequestered in our yard per added 1% of organic matter. Multiply that by our 11.8, and we get 6.8145 tons (x 2,000 = 13,629 pounds) of carbon sequestered within our backyard in the past 5 years.

For reference, a mature tree absorbs about 48 pounds of carbon per year (Source: European Environment Agency), so our backyard activity has sequestered about 284 tree-years of carbon. Also for reference, nearly 20 pounds of carbon dioxide are produced from burning one gallon of non-ethanol gasoline (source: US Energy Information Administration), so our backyard activity has offset about 681.45 gallons of gasoline. (With a 12 gallon tank, that’s 57 fill-ups.)

On the one hand, it’s a drop in the bucket. On the other… in this little place… it makes a world of difference. And it’s profoundly do-able for anyone who wants to sequester carbon in their yard. A movement for “Climate Victory Gardens” has published some helpful ideas for backyard-scale carbon sequestration.

Gabe Brown is a second-generation rancher in North Dakota, and since 1991, he’s seen an increase in soil organic matter from 1.9% to 6.1%. In his excellent book Dirt to Soil, he identifies five principles for soil health that he uses to manage his 5,000 acres:

Limit disturbance. Tillage releases soil carbon into the atmosphere and causes topsoil to erode away. Don’t do it. Chemical disturbances such as synthetic fertilizer, herbicides, pesticides, and fungicides also qualify as a type of disturbance.
Keep the soil covered. Bare soil is an emergency. Covering your soil prevents erosion and provides habitat for microorganisms.
Diversity. Grow as many different types of plants (and host as many different types of animals!) as you possibly can. Brown sows cover crop mixes with up to 70 different species!
Living Roots. Include perennials and cover crops in your garden plans so that there are living roots in the soil for as much of the year as possible.
Integrated animals. Intermittent predation by animals stimulates flushes of plant growth which pulse more carbon into the soil. Gabe uses cattle to rotationally graze his cover-cropped acres.

In conversation with these principles is emerging research from ecologists on the Intermittent Disturbance Hypothesis. Robin Wall Kimmerer, in her less-well-known book Gathering Moss, explains “diversity of species is highest when the disturbance occurs at an interval between the extremes. Ecologists have shown that in the complete absence of disturbance, superior competitors… slowly encroach upon other species and eliminate them by competitive dominance. Where disturbance is very frequent, only the very hardiest species can survive the tumult. But in between, at intermediate frequency, there seems to be a balance that permits a great variety of species to flourish.” As more research is published on regenerative agriculture practices, I bet we’ll learn that the disturbance caused by Gabe Brown’s cattle herd moving across the landscape actually supports the increased diversity of each acre they graze.

What I like about Brown is that he comes from a pretty standard (extractive, damaging) American farming perspective, and ends up becoming a champion of regenerative agriculture. We can do the same in our yards. We can convert monoculture lawns to polyculture garden beds, keep soil covered, plan for living roots in the soil year-round, provide gentle intermittent disturbance with animals, and cultivate maximum diversity.

Below, you can see many of these principles at work in my backyard: I’ve got plastic mulch I scavenged at The Predecessors under my zucchinis. I’ve removed the mulch from under my cabbages, kale, and tomatoes, and undersown a diverse cover crop mix, which is just beginning to germinate. Nearby in a temporary enclosure, the chickens are busy making compost and appropriate-scale disturbance in a bed that’s about ready to turn over to the next crop. Flowers peek out around the edges. Carbon sequestration is a joy!

Julia Frisbie has been gardening in Coast Salish territory for six growing seasons, and is thankful to learn from plants, animals, and people who have been here much longer. She’s grateful to her mom, Anne Kayser, for cultivating her curiosity, and also to Robin Wall Kimmerer for writing the book Braiding Sweetgrass, which transformed her relationship with the more-than-human world. Follow Julia’s micro-farm on Facebook, Instagram, and/or TikTok.

Turning a Lawn into More Planting Space

By Julia Frisbie

Posted Wednesday, March 10, 2021

In January 2016, we became homeowners rather than renters for the first time, so naturally, we set out to destroy our newly-purchased lawn.

So boring. So unproductive. It had to go. Here’s what we did, and how it turned out!

We decided to use sheet mulch. First, we flattened and peeled the tape off all our moving boxes and laid them out on the lawn as a weed barrier, and watered them so they wouldn’t blow away.

(We used straw bales for raised beds during our first growing season, because we knew there wouldn’t be time for all this cardboard to break down and let plant roots through before summer. It’s better to start the sheet mulch process in the fall if you have time.)

Then we brought in 17 cubic yards of compost. The ground was wet, and the truck sank into the backyard and almost got stuck. Total disaster. We like to live life on the edge.

17 cubic yards is a lot of mulch. But for the record, you can use this same technique on a smaller scale: you could build the frame of a raised bed directly on top of your grass, line the bottom with cardboard, and then fill it with bagged compost. We used a dump truck load because we essentially wanted to turn the ENTIRE YARD into a raised bed.

Anyway, we spread that stuff all over, laying down more cardboard mulch underneath as we went. Extended family members who had come to see the new house were quickly drafted.

After we ran out of moving boxes, we used wide rolls of extra-thick kraft paper. Sometimes we had to lie down on the paper to keep it from blowing away before the next wheelbarrow load was in place. Large-scale mulching is a team sport.

We planted perennials like herbs and blueberry bushes by cutting through the mulch and paper layers and putting their roots directly into what used to be the sod. Because it was the beginning of the growing season, we also transplanted some shallow-rooted annuals like onions and lettuces right on top of the compost. We planted our deep-rooted annuals (like nightshades, squashes, and brassicas) on the straw bales that year, because we knew their roots wouldn’t be able to break through the cardboard and paper layer until after at least one rainy season’s worth of decomposition.

Then, because we didn’t have mulch to spread over the fresh compost, we broadcasted wildflower and clover seed all over the place as a cover crop.

Our cover crop helped build more soil while (mostly) crowding out weeds. The wild birds loved it, and they came and pooped new weed seeds everywhere. Oh well! Still, we had a glorious first summer in the new place, with a few veggies, a lot of flowers, and very little mowing.

Our big break came months later when I heard a chainsaw and a chipper in the neighborhood. I literally chased the truck down the street barefoot, begging the arborist to drop his load of chips for us to use. He did– JACKPOT!!!– and our neighbor yelled at us about it, so the first thing we had to do was shovel the entire load (about 10 cubic yards) out of the easement and into the backyard in one evening. We didn’t have time to mow the cover crop first– we didn’t even have any houseguests to recruit. We just laid down a deep layer of arborist chips over everything. There are no pictures, because it was pitch dark by the time we finished. But it was time and energy well-spent. In the short run, it smothered the cover crop, suppressed weeds, and looked nice. In the long run, it composted in place and fed the soil, because arborist chips contain both green material (shredded leaves) and brown material (chipped wood). Five years and three additional truckloads of arborist chips later, this space is still feeding us and the wildlife with glorious abandon!

Why should you mulch your lawn into oblivion, rather than sod cutting, rolling it up, and hauling it away? Because of geology. Our island is what’s left after the rest got scraped away by a giant glacier. We’re pretty short on topsoil. Losing even two inches of organic matter was a price I wasn’t willing to pay– and besides, it composted in place in less than a year. Soil organic matter feeds microbes and absorbs water, cutting down on long-term water needs. And it’s like compounding interest; the longer you do it, the better it gets.

Fall is the ideal time to make new garden beds, but in a pinch, you can pull it off in early spring. As with other gardening topics, there are many good ways to do something, but no single “right way.” That said, here’s what I can recommend because it’s worked for us:

Lay down a compostable cardboard or paper barrier on top of your grass.
Get the barrier all wet.
Dump a bunch of compost on it, and spread it at least 4 inches thick.
Broadcast seeds for a cover crop. American Meadows is a decent source if you want to buy wildflower and clover seeds by the pound rather than the packet.
Make holes in the barrier and plant perennials straight through. Plant shallow-rooted annuals right on top during the first season. Remember to water well, because plant roots probably won’t make it through the cardboard and paper layer until next season.
Cover with at least a four-inch layer of arborist chips no later than the following fall. You can request arborist chips from local companies on getchipdrop.com and they’re FREE!
The next spring, gently rake the arborist chips out of the way and plant your annuals directly into the compost below.
Follow up with additional applications of arborist mulch on an ongoing basis every fall, or whenever things get weedy, or when you need a good workout, or whenever you feel like things are getting too peaceful with the neighbors.

Now, for a few warnings:

DON’T STOMP AROUND IN YOUR NEWLY PURCHASED PILE OF COMPOST BAREFOOT because it might contain silverware. Somehow this happens to us every time, no matter which of the two local suppliers we order compost from. I have a slight preference for Skagit Soils, but no compost you purchase by the dump truck load is going to be perfect.

DON’T PAY FOR FANCY WOOD CHIPS. They’re all brown material, rather than a mix of green and brown, so they won’t compost in place and they won’t be as good for your soil. Just get the free stuff from your local arborists.

DON’T MIX THE ARBORIST CHIPS INTO THE SOIL. That will tie up all the nitrogen, which will starve the plants. Just lay the chips on top like a blanket.

DON’T FREAK OUT WHEN WILD MUSHROOMS POP UP. They mean your soil is happy. They don’t compete with your plants, and they can’t poison you if you don’t eat them. Treat them as honored guests who bring good news and let them live their lives.

THERE WILL BE WEEDS. Why? Because the polyculture you’re creating is more attractive to wild birds than your boring old lawn used to be, and bird poop is full of weed seeds. The time you used to spend mowing, you will now spend weeding. But the more years you spread arborist chips, the easier it gets to pull the weeds, because the soil gets so spongy-soft. I’d rather be down on my hands in the duff than pushing some stinky old mower any day.

The End of Summer

by Peter Heffelfinger

posted September 21, 2020

The End of Summer

After the many days of forest fire smoke, with a lack of wind due to the inversion effect of the heavy haze, it was a relief this past weekend to finally see the sun and feel a small breeze. The extreme fire danger is still present, so one hopes we can get through the fall without any local blazes.

While the weather was on hold, the garden duties kept perking along. The last of the tomatoes needed to be processed or given away, the final cucumbers had to be pickled or made into appetizers, and the cabbage heads, both green and red, made their way into the sauerkraut jars. In June a third of my seed potatoes failed to sprout due to the wet weather, but, to my great relief, the rest of the seed ultimately produced a healthy harvest of Yukon Golds, La Soda Reds, and California Whites. To quickly cover the failed potato ground I planted a few hills of winter squash and pumpkins. By September that bare corner of the garden was filled with the bright oranges of Cinderella’s Coach squash and Sugar Pie pumpkins.

At the other end of the garden, a planting of standard pumpkins is offering similar pre-Halloween bounty, along with a great number of Vegetable Spaghetti squash. As the vines die back, all the members of the extended gourd family need to be moved to a dry, airy space to properly cure prior to storage indoors. It’s going to be a cucurbit winter.

Fall Greens

The early September plantings of Oriental greens, Miner’s lettuce, mustards, turnips and kohlrabi all came through the smoky stasis. As often happens, I seeded the bed a bit too thickly, so the first duty was to carefully thin the seedlings to give them proper spacing. For fall and winter vegetables it is important to leave extra room between the plants; they need to spread out a bit wider to gather the decreased light from the low-angled winter sun. At 45 degrees latitude north, our corner of the Pacific Northwest is halfway to the North Pole, and in winter is far removed from the more sunny south.

I also made a second planting of fall greens two weeks later, just in case there was any problem due to the continually grey days. If we get an extended stretch of warm autumn weather, both patches should do well. If cold weather threatens later on, I can set up small hoop houses of floating row cover to keep off the frost. I prefer row cover to plastic for winter protection, since it provides just enough added heat to protect hardy greens, allows the rain to water the beds, and also softens the harsh winds. Given our recent trend toward warmer but wetter winters, I’m betting that we won’t see any really hard freezes. But just in case, it pays to keep a supply of Agribon or Reemay row cover handy.

Fall Cover Crop

The fall equinox is also a good time to plant a fall cover crop. I prefer annual rye since it’s simple to plant. I find that most cover crop mixes include seeds of widely varying size, from large Alaskan peas to tiny crimson clover, with annual rye in the middle. It’s difficult to plant each seed at its proper depth, often resulting in spotty germination. I cover freshly seeded rye, lightly raked in, with floating row cover for a few weeks, as protection against hungry birds. If you wait to plant rye later in the fall, when the soil is much cooler, the row cover also provides just enough warmth to sprout the seed.

Row cover material is actually plain white interfacing, commonly used in lining down jackets and other clothes. Who knew it could also be used to protect gardens against the cold? A tool of the garment industry has crossed over into horticulture.

Fall Cover Crops

by Peter Heffelfinger

posted August 25, 2020

The first signs of fall usually arrive in late August: cooler nights, early morning fogs, and a few rain showers to break up the steady stream of sunny days. The change in summer weather is an early reminder that mid-September through October is the time to sow a winter cover crop in areas of the garden not occupied by fall greens or overwintering plants. A cover crop lessens soil erosion and runoff, as well as preventing compaction on bare ground. This is particularly important given the heavier winter rainfall that has been occurring with climate change. We are getting the same amount of rain overall, but it’s arriving in more intense storms. Not the usual Northwest slow drip anymore.

My standard cover crop is annual rye, since it is readily available, fairly inexpensive, and, if protected by row covers, can be sown in chilly conditions in late October and even into early November. (Note: do not use rye grass seed, which is a perennial for lawns.) Annual rye does not supply much nitrogen to the soil, but it develops a strong root system and stays a vibrant green even in the coldest winter weather. It will get lush and thick early in spring so it is important to till it in as soon as the soil has dried out enough to be safely worked. If the rye gets over 6-8 inches tall, mow or cut the tops before tilling or digging in with a fork, to hasten the decomposition of both the roots and the shoots. It usually takes a week to ten days to completely compost a healthy crop of rye into the existing soil. A second tilling may be needed to grind up any lingering root wads or clumps of ryegrass before preparing the beds for planting. The end result is a fluffy soil structure, high in tilth, that is ideal for the first crops of spring.

There are a variety of other cover crops, such as crimson clover, Alaska peas, or fava beans, but they are more expensive. They supply nitrogen to the soil, if needed, but I find the regular addition of compost and organic fertilizer materials is more than enough to keep a year-round garden adequately supplied with nutrients in order to grow healthy plants. To maintain high soil fertility I use worm castings, horse manure tea, or fish fertilizer during the growing seasons. Annual rye does what is most needed during the winter: holding on to the soil during the rain, and then easily dissolving into the ground just prior to the first spring plantings.

I do find that the rye seeds, which are only lightly raked into the soil, need to be protected against the birds, who will quickly descend on any freshly sown plot. There are always a few seeds left exposed on the surface, an instant food signal to every avian in the neighborhood, whether they are winter residents or preparing to migrate south. I immediately cover any new planting of rye, whether a raised bed or a big patch, with a light row cover material such as Reemay or Agribon, lain flat on the ground directly over the seedbed. To secure the material against the wind, I lay boards or heavy metal stakes around the edges, and distribute light metal stakes or wooden poles in the central areas. The white sheets will readily float away in even a light gust if you are not careful. Any revealed bare spots will instantly be targeted by every hungry sparrow.

The rye will sprout under the protection of the row cover, especially in late fall when the nights get chilly. Let the rye push up against the material until the shoots are 1-2 inches tall and are safe from the birds. Once the cover is off, the rye will be a green lawn all winter.

Note: be careful when raking in the rye seed. If you rake back and forth too much you risk piling up the seed in thick patches in some areas and very thin spots in others. To maintain an even distribution of seed, I use more of a vertical chopping movement with the rake, to bury as much of the the seed as possible in place. It avoids mounding up the seed at the edges of the bed or in little ridge lines in the middle of a bigger area. When I sow the seed by hand, casting it evenly all over the bed, it definitely feels like an ancient agricultural rite of fall.