Featured on Plant Scientist

I’ve been working with Sarah Shailes, the curator, and writer of the prestigious Plant Scientist blog, to feature The rules of spacing, which was such a hit here a couple weeks ago, on her site. She published it today. Thanks to Carolee, a follower of Mortal Tree, for already liking the guest posting. Find the post here: The rules of spacing


While you’re there, you might like to check out some of the other articles Sarah and her guest writers have compiled. I have followed Plant Scientist for years now, and always appreciate the detail of the subjects explored there.

Making sense of wild seeds

I’m not quite sure what it takes to sprout Turkish rocket (Bunias orientalis). Last year I posted a fairly certain observation that a couple weeks in cold temperatures does the trick, only to find in the comments from the ever apt Wooddogs3 that she had sprouted quite a few straight out of the packet in warm weather.

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Scratch that idea. I figured something else must have deterred my Turkish rocket sprouts; but then, in later conversation, Heather mentioned that more Turkish rocket sprouted after the pot sat out over winter. (?)

I think the fact of the matter is we are working with fairly wild, unselected seeds. With them, variance is the standard. At the same time, it offers several little known benefits.

Varying the time of germination increases the likelihood at least some of the seeds will sprout in a ‘sweet spot’ of a season, or at least avoid catastrophes, and make it to adulthood. What if an unusually late frost hits or some animal nips off the tender sprouts?

This is a very helpful character for love-in-a-puff vine (Cardiospermum halicacabum) which I’ve grown on a large scale for the last couple years. It’s a warm climate plant, and can’t take frost. I nevertheless plant it in mid April, when we still have a chance of frost. While a few will come up as early as three days after planting and get nipped, the majority of the plants take about two weeks to sprout, and will continuing sprouting up to three months after.

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Cardiospermum sprout back when I tried growing them in flats. Because their sprouting time was so varied,  I watered the flats a lot longer than expected for all the seeds to sprout. They don’t transplant very well anyway, so I now direct seed.

The mechanics that govern this variance can vary, but are usually based on the activity of certain enzymes releasing nutrients necessary to wake up and nourish the embryo that will become the new plant.

Health conscious readers may be familiar with the discussion of improved nutrition in sprouted or soaked grains because the phytates present in these seeds have been removed (see here for more info). This is because in the seed, phytates bind up nutrients -phosporus in particular- keeping them off limits for the embryo (1). Water is one factor that initiates the enzyme phytase, which is responsible for breaking up the phytates (2). In the right temperature range, phytase completes the breakdown of the phytates, releasing the nutrients the embryo needs for growth. In most cases, the need for adequate water and longer durations of certain temperatures ensures the plant can grow to maturity once it sprouts.

Of course, many of our perennial vegetables also need cold, moist temperatures, or dry and warm temperatures, in addition to a later stage of warm moisture to successfully sprout. Phytates are one example of the mechanics generally at work in seeds -enzymes releasing nutrient.* Differences in the genetic makeup can dictate the time each seed takes to activate these enzymes, and release the nutrients for sprouting. Its variance in genetics that often gives such extreme variance in sprouting time, and what conditions are necessary to induce germination.

Most of our garden vegetables were the same way at one time, with lots of variance. They’ve just been selected. If over the next ten years I only saved seed from cardiospermum that sprouted two weeks after planting, this character would soon be the norm.

Although it’s nice to have an idea what’s going on in those drab looking little seeds as they deny us a happy sprout, what can we do to improve the likelihood that we, at some point, actually get a sprout?

Heather had the right idea leaving her Turkish rocket in the pot to see if any more sprouts would show up. Just give the seeds time, and changes in temperature.

I know from experience that keeping a little empty pot of dirt safe for seasons at a time is not easy. As a first step, designate a spot where seeds are protected -by mandate of heaven -or whatever works for you. Tell this to anyone that might come along thinking your untidy plant-keeping needs tossed in the trash.

Rodents seldom care about the mandate of heaven, so cover the seeds with some mesh, or build a hanging tray well above the ground, as Martin Crawford does, to keep them out. I hung some trays in our greenhouse last year which did the trick keeping mice out of squash seeds. The only problem with hanging trays I find is their fluctuating temperature: pots placed on them can easily dry out on a hot day.

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Seeds are more likely to stay moist and live if they’re in more temperate climates surrounded by bricks in a shady corner. My favorite spot for sprouting is on the east side of our garage, or on the north side of our greenhouse. I’ll bring the trays from these temperate spots once in a while to the hot greenhouse. For a short time here, I watch them, and keep them watered, while transplanting any sprouts that appear. Once the sprouts stop appearing, I move them back to the less intense climate.

This system is very effective at getting around the errant nature of our prized perennial vegetables and trees. With such complexity, it’s better to just offer a variety of situations to seeds, and wait, rather than trying to guess what’s going on in those drab little seed’s dreams.

*There are even several kinds of phytase. See here for more info.

Orchard understory

Is the space around your trees still empty? Try these plants:

10 Companion Plants for Orchards (~4min read)

This article provides a pretty neat survey of plants that, together, make a diverse, healthy, productive orchard. Any of the listed plants of especial interest?

The rules of spacing

I was at a Christmas party in conversation with a local Timken engineer who, hearing I design food forests, wanted to pick my brain on apple trees. He had six trees in two rows of three, well spaced in his backyard. He was throwing out terms about the mainstream organic sprays he was using, and framed his questions expecting me to know some super organic spray, or spray regimen, that would fix his problems of pests and low vigor in general. I don’t think he expected the answer I gave: ‘What’s planted around the trees?’

We often think of the rules of spacing as rules for keeping other plants away from each other. In practice I find the lines blur between species, and enters a much more broad science: it’s what should be included near the plant, as well as what shouldn’t. Between these two aspects, you make or break the majority of fruit tree problems.

The lines often blur between species because, let’s face it, plants don’t grow in a vacuum and always have something growing up against them. In this guy’s case, his trees were planted right into his lawn. They were in competition with the grass.

Looking at their history, grass and trees are in most cases nemesis of one another. Trees make forest; but grass needs open space. The setting in most yards of trees with grass between is quite artificial, and only exists because we keep the grass mowed. In any other situation, trees would take over.

The prairies are the kingdom of grass, and these occured because of rain shadows, or areas where circumstances such as the Rocky Mountain range messed with the winds that carry rain, creating droughts in one part of the year, and near flooding in another. Trees don’t like that, because most have relatively shallow roots, as much as 80 percent residing in the top three feet of soil depending on the kind and its conditions; but prairie plants, such as the grasses, and N fixers like senna hebecarpa, put roots down unusually deep, so reach the water table whether rain comes or not.

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An experiment showing the root growth of Red Delicious apple tree two years after planting.
Have you ever wondered as you pass woods how the trees survive so close? If you were planting an oak tree in your yard that would someday reach a hundred foot tall, can you imagine the spacing recommendations? They would be over fifty feet apart. Most yards couldn’t fit more than one tree. But in the woods they stand on top of each other, growing for hundreds of years, happy, and healthy.

Studies have shown that trees can grow their roots deep into the ground, but prefer to keep their roots higher in the soil if possible. There is more organic matter, hence nutrients and water, in this layer. If there isn’t, trees will try to put in the work to grow deeper. This is a lot more work, and certainly isn’t their first choice.

What trees really prefer is building networks in which they share and preserve resources. For instance, trees have what is called hydraulic redistibution, which is a fancy term for moving water not only up for their own use, but back down into the soil for storage, and horizontally to other plants. Peter Wholleben, in his book The Hidden Life of Trees recalls his surprise when he found a ring of roots from a beech tree that must have been cut down well over a century beforehand, but still had green, living roots showing above ground. It had no leaves, and the stump was gone. As he explained, citing various studies, the living trees around this ancient (should be dead) tree were feeding it sugars made in their leaves, keeping it alive. Likely, they got some kind of kickback from the extended root system because it allowed them access to more resources.

This is in ancient, established forests, so conditions aren’t quite the same for our young transplants. We can get some similar effects by growing fruit trees in more open settings, or riparian zones. These are zones similar to fencerows and overgrown fields where grasses are just converting to trees. These zones are iconically untidy and wild; but skillful gardeners know the elements of these zones, like clay in a potters hand, have the best potential to form the most beautiful, lush gardens.

Riparian zones have many layers, with notably high numbers of low growing herbaceous and woody shrubs, many of which are nitrogen fixers. The quickest way to simulate this ecology is making ‘guilds’ of plants right around your fruit trees. Here is my manual of bed building for info on quickly clearing grass without tillage. Plan on expanding these plantings every year until the beds around your trees meet. If the tree is older, and larger, the bed should extend at least a couple feet beyond its drip line.

An example guild: 1. Fruit Tree 2. Comfrey 3. Siberian Peashrub 4. Amorpha fruticosa 5. Japanese Wineraspberry 6. Honeyberry 7. Blueberry 8. Turkish Rocket 9. Crambe cordifolia 10. Stepping stones, (or in this case, stepping logs). The green base is a ground cover of mint.
Any guild should include at least 2 woody nitrogen fixing plants, about 5 plants that do not fix nitrogen but can be cut for mulch, such as comfrey, or a groundcover of something like mint, then several fruiting shrubs like raspberry or honeyberry, and some perennial vegetables.

This is the best method if you already have fruit trees in the ground, like our engineer friend. If you’re just planning your food forest, Robert Hart, the father of the northern food forests, recommended planting full size or standard fruit trees at recommended spacing for their size, in rows like any orchard, but then semi standard or medium trees, then dwarf trees, then shrubs, then herbaceous plants, then vines to climb and fill in the cracks between them.

Photo credit: Graham Burnett.
I’d recommend mulching as much as you can, and planting that area with a complete planting like this. The space should be completly filled with plants, and will establish faster with less work overall.

This system gives quite attractive results that are increasingly less cost and labor than serial applications of even organic, clay-based sprays, pyrethrums and neems, let alone the more harsh chemicals. There is work later on, but this is of course dabatable, because its mostly harvests of fruit. Sounds like pleasant work to me.

Moles: a link in the trophic chain

“Mole starts with M, and and M is for meat” as I once read. Moles don’t eat much plant material, they mostly eat worms and grubs -meat. What does it mean if you have a high mole population? You have a lot of worms, grubs and the like -a thriving ecosystem to sustain the little diggers.

Farming with Nature: why we welcome moles on the farm (~2min read)

This article gives a little more explanation on how moles benefit their ecology. 

Moles also eat young, ground-dwelling cicada nymphs. We were plagued by the adult cicadas this year. If I can get a higher mole population, perhaps I’ll have fewer of these bugs when they’re next due to emerge circa 2029. That would be nice.

Making friends with rodents

Blurring gray fur and tails pour like a waterfall onto the floor in front of me. A tense minute, and the place is cleared -bare, clean cement floor, and nothing but hushed scurrying sounds all around. I’d just turned on the light.

This was one summer long ago, when several old building were torn down by the Township very near our chicken house. These were an old garage, another chicken pen near it, and a large old barn. They all housed droves of rats. Where did they go when these building fell? Our place.

We had quite a clean operation. When the rats came, we cleaned it to the max, removed all the wood shavings, straw bales, any and all feed -no matter how tight its container, and even some of the chickens. Despite the cleanup, the invasion lasted for months.

They were too smart to fall for traps. Eerily, one of the traps we found set off with no rat in it, had a freshly gnawed twig from the lilac bush right outside the pen stuck in it, the bait removed. My dad stayed up several nights shooting them with pellet guns. He terminated the lives of hundreds, but only recovered a few because the rats began eating their fallen, dragging them back into their holes immediately, or gnawing into them on the spot. To say nothing of a few unfortunate chickens that fell prey when the lights went out.

The rats made this new house their home in short order -with or without resources. They dug enormous piles of soil out from under the cement flooring, brought in food from some place. We had removed everything else.

When specialists begin throwing out statements about harshly mowing orchards to keep rodent and rabbit from gnawing away bark and roots of trees, I am a bit skeptical. These creatures create habitat for themselves and are part of thriving ecologies. They are eaten by almost everything, providing a vital link in the trophic system. If you have ever studied how these systems work, reducing one part of the chain, reduces, or at least effects, all the others following. If you reduce rodents, you by default reduce potential health of the trees you’re trying to protect.

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A casualty in my parent’s small orchard. This tree was about five years old when snow fell, and a freezing rain covered the snow with a sheet of ice that remained for about two weeks. Rabbits, mice, and voles ate everything they could get at, including large trees like this one. See the gnawed bark at the bottom.

Rodents feed into a very broad system. Finding examples of what happens when rodents are entirely removed is difficult because we have seldom pulled this off in outdoor settings. If we have come close, someone is also fertilizing and pruning a lot to make up for the loss.

Rodents have many immediate effects too. For one, they dig holes, which allow more air and water to percolate into the soil. This is very good for soil health.

It’s interesting to note the trees most immune to damage by rabbits, voles, etc. are single seeded species, like peach and plum. The species most vulnerable are multi-seeded species, like apple and pear. Rodents and rabbits, every couple of years when the food gets scarce, devour the bark off a couple of these trees, killing the trees. If they didn’t these multiseeded species have a higher chance of sprouting on top of each other, and choking each other out.

Only one successful seed is necessary to replace its parent. Rodents are a factor which ensures the chance any young tree grows to adulthood is very, very low. This is a good thing in natural conditions. It means trees are more likely to be well spaced.

But how do we make our tree “the one” that grows to adulthood when we’ve already taken spacing into account?

The most effective move is just installing tree guards; simple spiral guards are fine for young trees; tree guards like these are better for larger trees. Larger trees are less vulnerable to girdling, but I have seen trunks near five inches in diameter girdled to the hard wood if the snow lays thick enough long enough. For these sizes, I am not a fan of corrugated plastic pipe guards because they’re extremely hard to get on and off, often harming the tree in the process. Even covering the trunks with tinfoil or fine wire mesh is better than nothing.

Opaque tree guards also protect from sun scald: when bright sun reflecting off cold snow heats the cold tree bark, making it crack. This isn’t good. Covering the trunk helps prevent it.

Another tactic is to provide food for the rodents (No, I’m not nuts. Keep reading). The fact is, rodents and rabbits will be present whether you like them or not. If you mow the grass, they will dig tunnels. If you remove food, they will find it, and store it.

I’m not the only one recommending this. One extension service informational pamphlet extolled mowing the grass in an orchard to the finest bits to reduce cover, yet recommended throwing out sunflower seeds when the snow fell. This is intended to divert the eminent population of rabbits, voles, and mice -now forced into starvation.

Apparently the specialists are aware their mowing and trapping are only mildly effective, and that the real issue is diverting and blocking the rodents when times get tough, not killing them. Natural predators do that.

It seems most logical to just leave the tall grass and brush -at least in isolated corners, so the rodents can feed themselves.

There are also biological deterrants, such as Sepp Holzer’s bone tar. Here is a forum discussion on the subject. Sepp Holzer explains making bone tar and its use in his book. I own a copy, and quite like it. I have never gone through the trouble of making bone tar though. Tree guards have done the job for me.

There is an idea that planting certain bulbs and other plants around a tree deter rodents and rabbits -especially voles, which eat roots underground. In controlled studies, ground covers like Pachysandra species, and bulbs like daffodils are themselves very unpalatable to rodents. This doesn’t necessarily deter their cozying up to your trees.

I’ve had trees with no guard brutally stripped by rabbits, despite a ring of daffodils around it. Keep in mind, when hunger gnaws, rodents gnaw just about anything -tasty or not. While these plants might deter voles from eating roots, don’t expect these to block the possibility of girdling.

Ecosystems keep a pretty tight control on rodents and rabbits as is. If we simply focus on making a healthy, lush habitat, giving your trees the protection to make them “the one” that succeeds in growing to adulthood, the rodents can function less as your foes and more as your friends. The alternative is certainly not as pretty.

Mastering the Growing Edge

A while back, I launched a series on this blog, post by post unfurling ten plants that cover ground. Like vibrant streaks of color, new concepts and uses popped into these posts, until the original idea was far outgrown.

The series blossomed earlier last week into Mastering the Growing Edge. You could call it a companion to PASSIVE Gardening; although the main focus in MtGE is food forests and perennial vegetables. It ties the concepts of bed building, mulch management, ground covers, and bed builders into a coherent whole.

I was able to once again work with Kindle Direct Publishing to make the digital copy free for your download today, Friday (Feb 3), and Saturday (Feb 4).

If you don’t have a Kindle, don’t worry; almost any device that displays this post can display a Kindle book by simply downloading the free Kindle app here.

I hope to hear your feedback and see the results that follow your new-found knowledge. Like a bud coaxed into bloom, this book is meant to bring the plants of a garden to full luster of growth through healthy pairings. The plants manage a lot of the growth, leaving you more time to smell the roses.

The book cover below is linked to the digital and softcover book’s page -just click.