Mulch, mulch, mulch!


I like the color contrast going on here between pinkish fallen avocado leaves and the grey-green foliage of this California Fuchsia

[This is one post in a series of posts on the loving landscape, collected under the tag “Back to the Garden”]

Last week we talked about compost. This week, we touch on a second key to soil health, mulch.  Both compost and mulch foster the life of the soil, and both are important components of the loving landscape. Sometimes they are confused for one another, but they are quite different animals.  Compost, which we talked about last week, is more nutrient rich than mulch. It’s full of life, and inoculates soil with that life.

Mulch, on the other hand, is a blanket for the soil. (A blankie, as I think of it in my more regressive moments.) It is not a living material, as good compost is. Rather, it is made up of dead, dry plant matter (dead leaves, shredded wood, straw, etc.) which is spread to form an insulating layer over the soil. Simple as it is, a mulch layer is vital to the life of the soil. In nature, no one comes around with a rake to tidy up. Plants drop dead matter all the time, and that stuff lays there until it breaks down. That is how it should be. In a loving landscape, we try to replicate the patterns or habits of nature, and one of the most important habits she has is letting stuff fall and lay there.

This, by the way, entirely contrary to common gardening practice, which seems to believe that if a surface isn’t covered in turf or cement, it must be swept as clean as a kitchen floor. I see a lot of dead soil in my neighborhood, dry and exposed and baking in the sun–but ever so tidy.

Insulating the soil provides the conditions necessary for life to bloom in the soil. Mulch helps retain soil moisture (which lessens the frequency of watering) and protects soil life and plant roots from the extremes of hot and cold, and builds new soil over time. It provides habitat for beneficial insects (And yes, some not-so-beneficial ones as well. We’ll talk about that more.) So while it is not as biologically active as compost, it creates the conditions which support life.

Finally, mulch becomes soil. Over time, it slowly breaks down and becomes new soil. If you dig a hole in a yard which has been mulched for a few years, you can see the rich dark soil which appears just beneath the mulch layer, very different from the older soil lower down.


Let me tell you a story. Our friend Kazi recently bought a new house and is in the process of planting gardens in the front and back yards, which had been sorely neglected. In the big back yard she discovered the previous owners had, for reasons known only to themselves, blanketed the soil with big pieces of polyester carpeting and sheets of black plastic. Beneath this stuff, the soil was dry, hard packed and lifeless.

She threw away the plastic and carpet and put down a thick layer of shredded wood mulch. In addition, she ran drip lines beneath the mulch to bring some water into the picture. (That is necessary here, as we get so little rain–it wouldn’t be necessary everywhere.) She let that stew for a couple of months, and then checked back in.

As if by magic, the soil beneath the mulch had come to life. The water and the insulation called to the worms. They came from…somewhere. (The ways of worms are mysterious!) And they went to work opening up the lifeless, compacted soil, changing its texture and color. On a microscopic level, a host of bacteria and fungi had also gone to work in Kazi’s soil, producing nutrients in the soil, readying it for planting.

And all Kazi did was lay down a truckload of mulch, and then retired to her porch for a well deserved cocktail. No tilling. No digging. Nature does the heavy lifting.  This is the wonder of mulch.

Sound too good to be true? The underground, invisible life of the soil, and its relationship to plants is amazing. To learn more, check out the classic text: Teaming with Microbes by Jeff Lowenfels and Wayne Lewis.


Mulch  looks nice–at least to my eyes it does. I admit that I may have eccentric vision. Life is beautiful, and I see in mulched spaces the promise and hope of life. When I walk in our mulched yard, I can imagine I’m in the forest, walking in quiet leaf litter. Meanwhile, when I see vast tracts of green lawn, I think, “What is it feeding?” And the answer is, nothing. Lawn asks for so much in terms of time, labor, water and chemicals, and gives so little back. Whereas mulch costs little, and gives much.

If you decide you won’t have a lawn (or much lawn), mulch is one of the best ways to unify the look of yard and garden, to make it look tended and tidy. Mulch also represses weeds. I think of it–again–as a blanket stretched across a neatly made bed. Mulch is homey and comforting. It also provides a soft, clean surface for walking, and of course, there’s no worry about too much foot traffic!

Dogs, by the way, seem to do just fine on mulch. They don’t, contrary to popular belief, need a lawn. In fact, we all know they are hard on lawns.

As far as kids go, a yard full of trees to climb, secret forts, chickens, flowers, vegetable patches and interesting critters and bugs might better lure them outside than a perfect lawn. I know many happy kids who live in such yards. And as a kid myself, I preferred such spaces. I have no fond memories of grass. I do have strong memories of playing in wilder spaces–under trees, among boulders, in a rainy gutter, in the snow, at the beach. Lawn, for me, was always a suspicious place full of dangerous sprinkler heads and hidden dog poop.

The one exception I will buy for lawn is as a good surface for babies and toddlers. It’s nice to have a clean, soft patch of grass for them to plunk down on when outside. But that doesn’t have to be a big patch to be very useful and fun–and if the rest of the yard is full of life, they’re more likely to be visited by ladybugs and butterflies!


1) From the trees, from the ground:  Think of your yard as a closed system. Nothing leaves.  Leave the Leaves!  Nature doesn’t pack precious plant material up in plastic bags and send it to the dump, and neither should you.

  • Keep all of your fallen leaves. Get your neighbor’s leaves, if you can. Spread them in place, or store them in bags until you need them. Pine needles work, too.
  • Pull weeds before they go to seed and leave them on the ground to dry up and vanish into the mulch layer. I swear, it might look strange to see them laying there at first, all green and bright, but they’ll be pretty much invisible in a few days.
  • Practice “chop n’ drop”. When you’re pruning bushes or trees, chop up softer trimmings to about 6″ (15 cm) and leave them at the base of the plant. The plant will appreciate it. You can leave woody branches here and there, too, to support beetles and other bugs. (I make little piles of fallen wood, hoping to host lizards, but resign myself to the fact I’m more likely hosting mice. Well, it gives the neighbor’s cat something to do!)
  • If you have a lawn, save all your clippings. They make great mulch (and compost). To mulch with them, it helps if you can spread them out somewhere and let them dry for a day or so, so they lose moisture and won’t mat together. (ETA: a commenter just reminded me to be careful if you are sourcing your grass clippings from outside your home. If the grass has been treated with pesticides or herbicides, you will bring those into your ecosystem.)

2) From your city. I can’t speak for all cities, but most have tree trimming crews, and they have to do something with all that stuff, so many cities have public piles of both compost and mulch for the taking. We often visit the free pile of mulch in Griffith Park, not far from the putting range. We only take their mulch, not their compost, which we’re a little suspicious of.

On that note, not all mulch is created equal. Check the pile before you start shoveling to make sure the wood is ground up enough–there shouldn’t be too many big chunks of wood. A few big chips are okay here and there, but it should be shredded, not just vaguely chopped up. There also shouldn’t be too much garbage mixed in–bits of plastic and the like.

3) From tree trimmers. Shredded tree trimmings are one of the best kinds of mulch we can use. When arborists or tree trimming crews are working in your area with a wood chipper in tow, go talk to them and ask if they have plans for all those trimmings. They may be willing to dump them in your driveway for free.

We recently posted about someone working on an app to unite tree trimmers with people who want mulch. This revealed that 1) sometimes getting those guys to deliver is easier said than done, and 2) that some areas already have networks which link up tree trimmers with mulch-needers.

As to point one, I’d say that you should just keep trying and be willing to pay a little if necessary. For our most recent mulch delivery, we actually paid our arborist’s crew $50 to bring us a mountain–a literal mountain–of mulch, enough to cover our front and back yards. It was worth the money.  As to point 2, check around and make sure that there isn’t a system already set up which you can take advantage of–talk to your neighbor with the richly mulched yard for a start. Where did they get theirs?

4) From the feed store. Straw (not hay!) can be used as mulch, and one bale will go a long way. Now, admittedly, it does make your yard look like the set of Hee Haw, but it works. We covered our entire back yard with straw one year, just for the hay of it. Generally speaking, I’d reserve straw for certain uses in the vegetable garden, which I’ll talk about in a bit.

5) From your recycling bin. It is possible to use shredded cardboard and paper as mulch. It can turn a little unsightly, but it is a nice way to return some paper to the soil. More often newspaper and cardboard are used in specialized gardening techniques like lasagne or sheet mulching, and in lawn killing.

sunflower seedling

This volunteer sunflower seedling is a little stressed, but I think it might do better now that it has a nice blanket of dead weeds.


Mulching perennials

It’s a fantastic idea to spread mulch under all your perennials–all your bushes and trees. In fact, I think this should be law. (If only I were Queen of the Universe!) About 3 inches (7-8 cm) is a good amount. (You use thicker mulch layers for killing lawn and repairing soil. In those cases you lay down something more like 8 inches (20 cm)).

You can also mulch fruit trees with compost instead of wood-based mulch, to give the soil life there a boost, or lay down an inch or so of compost, and then top with mulch.

When mulching your trees and bushes, be sure to leave a couple of inches between the mulch and their trunks. You don’t want the mulch creeping up the trunk–it’s not healthy for the wood.

Mulching your paths, seating and play areas

This is a great way to repress weeds, keeps down dust and mud and make your yard look tidy. It is also fundamentally pleasant to walk on a path of mulch.

Mulch used in open spaces like this can be applied fairly thickly, say 5″ (13 cm), so you have a solid layer which resists foot disruption and smothers the weeds. There’s no need to put anything under the mulch in these situations–not cardboard or newspaper or plastic.

A nice side benefit is that you are protecting and nourishing the soil in those areas, so that one day, if you decide to re-arrange your yard and plant in those spaces, the soil will be in much better shape than if it were paved over.

(ETA 5/15: A reader reminds me to mention that it is a good idea to leave some soil bare in a yard for native bees and other insects. Some native bees harvest dirt and mud for their nests, others nest in the ground and need access to the soil. I’m going to do a whole post on native bee habitat later in this series, so you’ll be hearing more about this. In the meantime, just keep in mind the idea of leaving the odd corner or bit of slope un-mulched.)

Mulching vegetables:

Mulch in the vegetable beds is potentially useful, but also has downsides. It’s very specific and local knowledge, so you have to see what works best for you.

I’ll say straight off that if slugs are a big pest in your vegetable beds, mulch will provide them with lots of nice habitat, so I’d not mulch anywhere near my vegetable beds in that case.

A mulch of clean, bouncy straw can be useful for keeping fruit off the soil. How did strawberries get their name, after all? They are traditionally grown on straw. Yes, indeed!

Erik and I mulch our tomato beds with straw. It insulates the soil and keeps low fruit off the soil. We wait to mulch the beds until after the seedlings are a few inches tall, out of bug noshing range, to be sure we don’t inadvertently host any chewing critters.

Same goes for squashes and pumpkins–sometimes it’s nice to put the ripening fruit on a straw cushion.

However, we don’t mulch our lettuces and leafy greens, though a straw mulch looks pretty among greens. Maybe if Garden Beautiful was visiting for a photo shoot, we’d do a temporary mulch for looks. But bugs that like to eat succulent greens seem to like to bed in mulch, so generally it’s a no-go for us.

All of what I said may not be true across the board. I hesitate to give generalized garden advice, because every situation is different.

Mulching California natives:

This is a charged topic. I can’t speak to native plants of any other region, but here in California we are often sternly advised not to mulch our native plants. I ignore this to a certain extent. In general, I understand the logic. Our chaparral plants are not denizens of Mirkwood Forest. They need sun and air and some dryness. In fact, some like to be dry all summer long. So while it might work for non-natives, it would be wrong to put them on a drip system that waters them weekly and then bury them under several inches of wood chips. They’d suffocate.

Nonetheless, as I said above, Mother Nature is not busy with her broom. All plants drop leaves, even natives, and I leave them in place. Sometimes leaves blow among them from other plants. I leave those, too. If I pull weeds around the natives, I leave those in place. As a result, my natives are lightly mulched, and seem happy enough about it.

Mulching your lawn:

Mulching is one of the best ways to kill your lawn. Instead of going through all the trouble of tilling or solarizing, just lay down a layer of cardboard and a super thick layer of mulch and wait. If you’re interested in doing this, check out this series from UC Davis “Stacey’s Lawn Removal” where a woman walks us through her lawn removal using this technique. As a bonus she has lots of planting suggestions, too.

Mulching your lead-contaminated yard:

Mulching is one way to minimize the impact of lead in your soil. If your soil tests positive for lead, all you can do, short of replacing all of it, is to cover it up. You could choose to pave your yard, or put down a lawn, but mulch is cheaper and easier, and more soil-life friendly than those options. It works by keeping the soil covered, so that lead-laden dust doesn’t swirl into the air, and it keeps little kids who are toddling around up and out of the dirt, so they don’t get it on their hands, and into their mouths.


Reapply your mulch as often as necessary. Sorry I can’t be more specific! Different mulches will break down at different rates in different climates. Just check your mulch levels and add a little more. This should be no more than an annual chore.


Some kinds of mulch kills plants:

Use some caution with leaves or wood from plants known to be allelopathic–that is, hostile to other plants, like eucalyptus and black walnut. It’s not as big of a problem as you might think. They haven’t been able to prove that cedar chips, for instance, actually inhibit plant growth, despite all their bad press. But it’s a nuanced situation, and this article by Linda Chalker-Scott is helpful in sorting out the details.

Mulch encourages termites:

Do termites feed on mulch? Yes, apparently so. But it’s complicated. The University of Florida IFAS Extension did a study on this, and decided, in their conclusion that we may as well keep using it:

Further research on mulches and termites is warranted to determine if we should be concerned about using mulch around houses. Also, research is needed on possible repellent mulches such as melaleuca which might serve as an additional barrier for household protection against termites. At this time the benefits of mulches such as water conservation, reduced used of herbicides, and reduced soil erosion are very apparent while the risks to termite infestations due to mulches are unknown. Homeowners will continue to use mulches in landscaping around their houses and buildings. Our current recommendation is to be vigilant and up-to-date with termite inspection and treatment.

Wood mulch robs nitrogen from the soil:

There is also a persistent rumor going around that wood chips or shredded wood mulch robs the soil, and thus your plants, of nitrogen, so you shouldn’t mulch with wood products. While it’s true that the carbon in the wood is looking for nitrogen in the soil as the wood breaks down, but the exchange is very slight, and will not inhibit your plants. Mulch encourages life in the soil, the vital, microscopic life which actually produces nitrogen to feed the plants. (Again, you’ve gotta read Teaming with Microbes!)  The good that mulch does for the soil vastly outweighs the small amount of nitrogen lost where the wood touches the soil.

Bad Mulch?

If any mulch could be considered “bad,” I’d have to point a finger at plastic sheeting and rubber mulches. The problem with these is that they don’t break down and feed the soil. They do some of what mulch is supposed to do, but ultimately, they are not friendly to the life of the soil. Worse, they linger eternally and I guarantee you that one day in the future you’ll be pulling up handfuls of the dratted stuff, cursing yourself for ever thinking it was a good idea to use it.

Gravel mulch and decomposed granite (D.G.)  is somewhere in between. It at least rock belongs in the soil, unlike plastic and rubber, but it doesn’t feed the soil, and almost always is installed with an ultimately problematic layer of plastic sheeting underneath. I could do a whole Tumblr of photos from our area of people who put down plastic sheeting and rock in hopes of having a trouble-free landscape, only to find themselves hosting a fine weed farm. It is far better to put organic mulch down on bare soil. I can’t say it enough–imitate nature and you’ll be fine. Try to be clever with man-made materials, and you’ll be looking at woe down the road.

I speak from experience. Long ago we put down a layer of plastic weed barrier beneath a decomposed granite surface in our yard. That idea didn’t work out and the granite is long gone, but the plastic, despite our efforts, still shows up when I’m digging around. More than a decade down the road, it is in tatters and shreds and is absolutely miserable to remove.

So, learn from our mistakes, and…

Love Your Mulch!

The Connection Between Human Health and Soil Health

What’s the connection between soil and human health? It’s an intriguing question that family physician and author Dr. Daphne Miller discusses in the lecture above and in her book Farmacology: What Innovative Family Farming Can Teach Us About Health and Healing. In the research for the book Miller visited farmers who, as she put it, “farm in the image of nature,” who approach the farm as a living organism.

While she cautioned that there is little research behind the connection between farming practices and health, she suspects that biodiversity on the farm may be an important factor in our well being. To back this idea up she cites:

  • Erika von Mutius, who found an intriguing connection between children who grew up on farms and their lack of asthma and allergies later in life.
  • Research that is taking an Integrated Pest Management approach to cancer, treating it as a symptom of a lack of internal biodiversity.
  • Studies that have shown the higher nutritional value of eggs from chickens raised on pasture.

It seems obvious that there’s a connection between the health of a farm and our own health. Biodiverse soils produce healthier, more nutritious food. And way too much of the food we eat comes from farms where the soil is treated as a sterile growing medium. As Miller notes, “We are the soil.”

Garden Amendments as Placebos

I just finished writing an article for Urban Farm Magazine on the subject of aerated compost tea (ACT for short). It proved to be one of the most contentious subjects on which I’ve ever tried to, as Mark Twain liked to say, “corral the truth.”

It got me thinking about other controversial soil additives popular in organic gardening and farming circles right now such as rock dust, mycorrhizae additives, and biochar.

Now I prefer not to touch these topics with a hundred foot pole. But let me go out on a limb with a thoughtstyling outside of the usual debate about the benefits or worthlessness of these soil potions. I’ve started wondering if the strong anecdotal evidence supporting things like ACT, biochar etc., might indicate a kind of ecological placebo effect at work.

Note: I’m not saying that placebos have no value or that, “It’s all in your head.” Quite to the contrary: the placebo effect is powerful and causes real changes in the physical world. Even hardcore skeptics agree with me on this (note also the downside to placebos in that article). As the fifteenth century alchemist Paracelsus said, “You must know that the will is a powerful adjuvant of medicine.”

So could working with these soil additives be a way of focusing human will, of changing human consciousness towards the goal of healing the damage to nature that we’ve caused? And what about biodynamics? I suspect a consciousnesses shift within human hearts and minds is what Rudolf Steiner was really trying to do with his, admittedly bizarre, preparations.

On the opposite, non-interventionist side of the gardening spectrum, I’ve been re-reading Masanobu Fukuoka’s books. Fukuoka advocates a radical, almost (but not entirely) hands-off approach to natural systems. Paradoxically, Fukuoka was striving for the very same shift in consciousnesses, though by entirely different (Eastern) means. As he put it, “The ultimate goal of farming is not the growing of crops, but the cultivation and perfection of human beings.”

I think we would do well to spend more time investigating the intersection of human consciousness and ecology in the years ahead. Our survival may depend on it.

Now, as Marshall McLuhan was fond of saying, “If you don’t like that idea, I’ve got others.” So let me know what you think in the comments . . .

What Do Microbes Have To Do With Homesteading?

So what are the activities that microbes make possible around the homestead? To name just four:

  • Fermentation
  • Beekeeping
  • Soil Fertility
  • Human beings

Pretty important stuff. In fact, new systems thinking, applied to our natural word, is demonstrating that things like human beings are really just symbiotic sacks of microbial life. An article in the Economist, “Microbes maketh man” discusses just how important microbes are to human health:

The traditional view is that a human body is a collection of 10 trillion cells which are themselves the products of 23,000 genes. If the revolutionaries are correct, these numbers radically underestimate the truth. For in the nooks and crannies of every human being, and especially in his or her guts, dwells the microbiome: 100 trillion bacteria of several hundred species bearing 3m non-human genes. The biological Robespierres believe these should count, too; that humans are not single organisms, but superorganisms made up of lots of smaller organisms working together.

Natural beekeeper Michael Bush has made the same argument about bees. Elaine Ingham has emphasized the importance of microbes in soil.

Mess with the complex interdependent relationships between microbes and people, soil etc. and you’re asking for trouble. This, for me, is the argument against things like GMOs, Miracle Grow or conventional chemical beekeeping. We don’t know enough, and probably never will know, how 100 trillion bacteria will react to our latest innovation. Best to be conservative when it comes to microbial life.

Looking forward to seeing more of this microbial paradigm shift in science.

Peat-free Planting Mix Recipe With Coconut Coir

Nancy’s coconut coir-based planting mix. Here she’s doing the squeeze test, which we talk about below.

From an environmental perspective peat moss is a nightmare. Mining of this material is unsustainable, contributes to global warming and destroys habitat for many plants and animals. But, for starting seeds, we’ve used it for years. Our friend Nancy Klehm taught us recently how to make a seed starting mix with coconut coir instead of peat moss. Thanks, Nancy! Here’s how to make it:


Watering the coir brick to break it up. Once saturated, this brick will expand to fill the tub.

COIR:  A fibrous material made from coconut husks. It is sold in compressed bricks which expand greatly when wet. It is pH neutral and has no nutrients. Its role in planting mix is to hold moisture. Coir is the environmentally correct alternative to peat. Peat is mined out of peat bogs, which is a disruption of an ecosystem. Coir, meanwhile, is a by-product of the coconut industry. Of course, it has to be shipped in from the tropics, so is not particularly sustainable in that way. Nothing is perfect. So, if you have peat on hand or prefer peat you may use it in this recipe instead of coir, just substitute it, 1:1.

PERLITE: Perlite is a volcanic glass which, upon being subjected to extremely high temperatures (850C +), puffs–sort of like popcorn, or a Pop Rock. Obviously, though its origins are natural, it is an industrial product, but it is very useful for making soil fluffy and light. You will recognize it as the “white stuff” that you see in the soil of nursery plants. As it is essentially a rock, it is a neutral player in the mix. It simply keeps things light.

Note: you should avoid breathing perlite dust when working with it.

Store-bought worm castings. Homegrown, of course, are the preferred alternative!

WORM CASTINGS: Castings bring healthy microbial activity to the mix, as well as balanced nutrients and trace minerals. In addition, they hold moisture well. They are invaluable players in this mix. You can buy worm castings at the nursery, or you can keep a worm bin and harvest your own. Store bought and homegrown castings have very different textures–the store bought tends to be very fine, almost a black powder, whereas castings fresh out of the worm bin have more of a open, grainy, soil like texture– and this effects the recipe.  

For the purposes of this recipe, we will assume you are using fine-grained, store bought castings. If you have your own castings, congratulations! But you will have to play with this recipe a little bit. You will use a little less coir, because your castings (probably) have loft or springiness of their own. We can’t tell you exactly how much less coir, because castings vary.  Start, say, with half the recommended quantity of coir in the recipe below, and then test the mix, and add more coir as necessary. The proof will come in the squeezing. Do the hand test described in the instructions below. If the mix won’t hold form when you squeeze it, you have too much coir, if the clump you make doesn’t break easily, there isn’t enough. Again, see below.


This recipe makes about 4 gallons of planting mix. To make more or less, just use the same ratios. 


We like to mix ours up in 5 gallon bucket, but you can do this on a tarp or in a wheelbarrow or whatever you like.

You will also need something big, like a cement mixing tray or tub to soak the coir brick in. Remember, one brick swells into to a big bag’s worth of wet coir. If you don’t use all the coir, you can store it in a plastic bag. If it dries out, it can be re-hydrated.

You will also need a measuring tool. For this 4 gallon recipe you will need a quart measure to scoop the materials out of the bags–like a big yogurt/cottage cheese container, or something with same volume. Again, you can make as little or as much as you want using the same proportions, so your measure could be a 1 cup scoop or a 3 gallon bucket.


Prepare to make the mix by soaking the coir in a large tub of water for maybe a half hour or so. Break it up as it expands. It will drink up a lot of water and grow proportionately huge. Add water if necessary so that it all gets evenly moistened. When finished, it should be wet but springy, like a wrung-out sponge.

Put it together

3 quarts/parts worm castings (store bought, see notes above for homegrown)
8 quarts/parts coir
4 quarts/ parts perlite

Measure out the worm castings and coir into a five gallon bucket and toss them together with your hands until they are evenly and thoroughly mixed. This mix should be moist and dark, again with a nice “wrung-out” sponge level of dampness.

Only when those two are mixed should you add the perlite. It’s easier to mix the perlite in last–trust us. Mix the perlite into the coir/casting blend until it is also evenly distributed–the mix should be absolutely consistent–no patches or clumps should be visible. You might find it helpful to dump the mix back and forth between two five gallon buckets to speed mixing.

After it is mixed, pause to analyze the texture. Gather up a fistful, squeeze it hard and open your hand. The mix will form a ball in your fist, but if you turn your hand over and drop the ball a few inches, it will break easily. Overall the mix should be moist, light and springy. We can’t emphasize that enough. Moist, but not soggy. Springy, not heavy.

If the mix seems a little clumpy/dense/heavy don’t be afraid to add another part of perlite. It is better to err on the side of too much perlite than too little. Lightness is everything.

Measuring into the buckets with a quart-sized yogurt container. If you have two buckets, you can pour the ingredients back and forth between them to speed mixing. Otherwise, just toss the ingredients with your hands in one bucket.

Notes on growing

The seedling feeds itself from its seed body up through the formation of the first set of leaves, the cotyledons. After that, it is dependent on the nutrients in the soil. Your seedlings will be fine in this planting mix until around the time of the full unfurling of their first true leaves (the ones that come after the cotyledons). At this time–or no later than the opening of the second set of true leaves–you will want to feed your seedlings by watering them with some kind of diluted organic fertilizer of your choice. Do this maybe once a week until you transplant them.

Feeding accelerates root growth which is even more important to plant health than leaf growth. It prepares the plants to thrive after transplanting.

For most seedlings this means the first feeding would occur about 3-4 weeks after planting. The seedlings should be transplanted by 6 weeks of age–either into the garden or into bigger pots with real soil.


You can re-use this mix to plant more seedlings, but you’ll want to recharge it by adding in more worm castings. Just dump out your seed starting trays, mix it all up and let it air a bit. Also, the coir breaks down over time, so you find you need to add more of that as well. And if you add enough castings and coir, you’ll probably want to add more perlite to balance it. There’s no recipe–you’ll have to use your intuition to create a consistency that resembles the original mix.

Or you could compost it and start fresh. It’s safe to compost perlite, as long as you don’t mind having little white perlite bits all over your yard!

This is the surface of the finished mix. It’s so light and moist that it has holes in the surface. Note the even integration of the three ingredient: no lumps or patches left unmixed.

Another planting mix option is part coir and part compost. This is provided your compost is of the best quality–bagged compost from the nursery is not good enough. This is a hard area to generalize about because compost varies wildly in both quality and consistency, but you’d want to use lovely, lively, springy, sweet smelling compost.

Gardening guru John Jeavons starts his seeds in mix which is 1 part compost and 1 part garden soil–soil dug from the same beds the seedlings will be going into. This way the seedlings are already accustomed to the local soil and don’t go through so much shock upon transplanting. It also makes his garden a “closed loop,” meaning he doesn’t have to buy anything or bring any materials in from the outside. This saves money, keeps things local and prevents the accidental importing of diseases.

Using compost and soil works for him because he’s got top-notch compost and rich, fluffy soil–the kind of soil you can plunge you hand into up to the wrist without meeting resistance. This should be a goal for all of us to work toward, but in the meanwhile, while we’re developing that soil in our own yards, we’ve got perlite, worm castings and coir!

Testing the Lead Testers

Varian ICP-MS from Wikipedia

Dear readers,

Excuses for a technical post here, but we need your scientific expertise. If you have experience in soil laboratory testing techniques, or know someone who does, please send us an email at [email protected] or leave a comment. We’re attempting to reconcile slightly different lead results from three different labs and I’d like to be able to write about soil testing methods. Two of the labs we sent samples off to (UMass and Timberleaf Soil Testing) use inductively coupled plasma mass spectrometry (ICP) to test for lead. Wallace labs uses an extractant, AB-DTPA (ammonium bicarbonate Diethylene Triamine Pentaacetic acid).

Here’s how Wallace described their lead testing techinique,

We use AB-DTPA (ammonium bicarbonate Diethylene Triamine Pentaacetic acid).

It is a gentle extractant and it mimics roots in extracting minerals from the soil. Most often environmental tests are made with boiling acids which are more aggressive than roots. The AB-DTPA method is a standard testing method of the Soil Science Society of America. It is called the universal extractant. It measures the bioavailable or plant available minerals which is expected to be adsorbed by plants. Most of the background heavy metals are occluded and are unavailable to plants. Our testing does not see the occluded metals.

Total lead is approximately 10 times higher than our AB-DTPA measured lead. We recommend that AB-DTPA lead be less than 30 parts per million for home production of edible produce.

UMass says,

We use a modified Morgan solution (dilute glacial acetic acid and ammonium hydroxide) to measure extractable lead (using ICP).  Total Estimated Lead is calculated using a correlation established during a study performed here at UMass that compared total digestion levels to extractable levels using 300-400 soils.

I divided one soil sample into three parts and sent a portion to three labs. While all three labs indicated the presence of above natural levels of lead, there were enough differences between the tests to warrant a closer look at the techniques. Your assistance would be greatly appreciated and we’ll share what we find out.

Too Much Phosphate

Symptoms of chlorosis. Image from the Washington State University

Our possible backyard lead situation is a good reason to get a soil test, but if that didn’t convince you the Garden Professors at Washington State University just blogged about another important motivation: the bad effects of too much phosphate.

An overabundance of phosphate can interfere with a plant’s ability to uptake iron resulting in interveinal chlorosis, a yellowing of the leaves between the veins. So adding fertilizer that contains phosphate to soil that doesn’t need it is a waste of money, damages the environment and can kill your plants. Of all the soils I’ve tested in Los Angeles, all are already high in phosphate, meaning that most fertilizers, both organic and chemical are both unnecessary and potentially toxic to plants.

As the Garden Professors also note in another post, it can be very difficult to diagnose problems just with visual cues. Chlorosis, for instance, can also be caused by other factors.  As Garden Professor Linda Chalker-Scott puts it, “You can’t fly by the seat of your pants on this one, folks.” While I’m probably a bigger proponent of intuition and “woo-woo” than Chalker-Scott, I think it’s a good idea to balance our left and right brains. No reason you can’t get a soil test and talk to those plant Devas.

Till vs. No Till Poll Results

US Department of Energy

Our highly unscientific till vs. no-till poll results are in:

17% of you said you till
43% of you don’t till
23% of you double-dig
15% are undecided

Looks like most of you fall into the permacultural no-till camp.

For more information on no-till ag see the no-till section of our publisher Rodale’s website.

Meanwhile, we’re on our book tour of Northern California and the Pacific Northwest. Check out our schedule here and we hope to meet all you all!

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