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.
Sunchokes is number ten in the Top 10 ground covers for food forests series I started a while ago. To help put everything into perspective, I made an infographic.
The ground cover branch on the visual archive has links to all the original posts if you would like to find out more.
In general, the layout from right to left are ground covers that do well in established beds, to plants that simply wipe out other plants, and are excellent for bed building.
If you’re wondering how to share this on your own social media pages, try the share buttons below the post. I have most social platforms available for sharing.
I’m using the the term “dynamic mulch” to describe the ground covers, because ground cover has a rather flat connotation. Most gardeners think of them as useless plants that do nothing better than excessively clog the soil surface. They have much more potential.
I’m suggesting these plants as tools, not just for blocking weeds, but actively removing weeds, making use of otherwise useless plants through careful combinations, getting food from ground cover, improving the quality of the soil, and feeding other plants through their well calculated use. With the correct use, resulting from a more dynamic comprehension of plants, we are suddenly on the brink of an entirely new level of sustainable, productive, passive agriculture and gardening.
The infographic, and the Top 10 series are part of a bigger surprise to which some of you closely following me have probably caught on. It should be ready before the end of the month. My apologies for making you wait, but I assure you, it will be worth it.
I’m always writing about perennials and no till, but I actually do a lot of annual gardening. My family’s farm has a CSA for about 20 shares that uses about 3 acres of tilled gardens.
Mortal Tree is my exposition on alternative methods, so of course I wanted to try growing annuals in a passive, no till setup.
That’s what the keyholes at the front were supposed to be; with perennials thrown in for propagation, and greater efficiency.
After two years of the first “system” (or lack thereof) there are two problems: lack of fertility, and weeds. Of course everyone has those problems, but the system was supposed to keep these to a tolerable level.
As it is, aside from mache, annuals just aren’t satisfied with the fertility. This year I didn’t harvest anything but what the perennials willingly supplied.
Ideal weed level is pulling a few weeds as I inspect the garden on a pleasant evening. Instead, I found myself clearing whole beds only to have them full of weeds again in a month.
I’ve scrutinized the system and found two problems: lack of mulch and lack of fertility in general.
The year of high fertility
I got the idea I wasn’t cycling enough nutrients from the lack of vigor the annuals and their self seeding progeny showed. I wasn’t sure how much more I needed. Normally the tillage and compost in the big gardens makes everything grow without complaint. Now that I’m trying to make this work with comfrey and other in-system nutrients, without tillage, it’s not.
Martin Crawford has several tables in Creating a Forest Garden that really pin down nutrients and how much different plants need, and how much different sources offer. He has a light, moderate, and heavy cropping category, then annuals.
Most of the perennial vegetables he places in the light cropping category. It takes about two cut comfrey per square meter to sustain these plants, which is about what I am applying. To sustain annual cropping takes 60 cut comfrey for that same area. Problem found.
The amount of fertility I’m accustomed to working with in the annual gardens is simply an unnatural surge of nutrients. Compost is extraordinarily rich in nutrients compared to bulk green mulch.
Also, tillage forces more oxygen into the soil, breaking down those nutrients at a faster rate. The keyholes had this advantage at first because I dug out the paths and piled up the soil to make the beds.
Problem is, the mulch apparently needed for the annuals would drown most of the perennials. In response I’m moving all the perennials out, and making the keyholes completely annual.
The best comparison I have for this so far is a keyhole bed I have near the Willow Garden in its fourth year of no till.
It has a dug out path and raised beds too. It has one comfrey for its mulch and fertility source. As a result, I’ve had to bring in more mulch to sustain the system.
For instance, I brought in a lot comfrey from the Willow Garden to drown out some quack grass (Agropyron repens) that had moved in. It was rather effective at suppressing it. Besides some vegetable mallow over the summer, it was enough to grow some nice cabbages.
In the food forest, I’m not supplying 60 cuts of comfrey per keyhole per year. I’ve got 12 beds with an average of 1.3 square meters each. It would take several hundred plants.
When faced with a large surge of energy in a design, I always try and disperse the blow across many sources.
Young regrowth on a coppiced amorpha
According to Martin’s fertility tables, one amorpha, based on mature canopy size of about six feet in diameter, provides the equivalent nitrogen of 20 cuts of comfrey, or 10 comfrey plants; lespedeza about the same. I’ll throw some of these in the patch so the roots sloughing off after coppicing can feed the comfrey. They need nitrogen themselves.
This still requires more space than I’ve allocated to the annual’s mulch patch. So I’ll grow some annual cover crops on the keyhole beds once in a while to fill the gap -careful to choose crops that will die when cut, frosted, or heavily mulched since there won’t be any tilling.
To really cinch the deal I have the food forest rabbit’s manure. I let a bucket of it sit out to catch rain, and harvest the resulting “tea” to feed establishing beds right now. In time it can be exclusively for the annuals.
Achieving this much mulch in the food forest will take a while. I’m moving out the perennials first, and planting the whole thing in lots of annual cover crops. The first plant to start yeilding mulch will likely be comfrey, though I might just mulch their own patch the first year to ensure they are established. The next year the N-fixers will be ready for light coppicing, then full production. I’m assuming three years before that point, but I’m quite excited to the see the results. I’ll keep you posted as it goes along.
Frost came and the Amorpha is done growing for the season. Check out this year’s growth.
Visually impressive I know. It’s actually lacking 2 ft of what I expected. If you’ve read Dealing with deficiency earlier this summer, you probably noticed this season wasn’t stellar for lush growth.
Compared to the nearby cherry that yellowed and lost its leaves several months ago, the amorpha did quite well, remaining green and vibrant, growing for a lot longer than other plants in the food forest. Early September even it slowed down and aborted its growing tip, calling it quits for the year.
Last year it grew right until frost in October. If the same had occured this year, I suspect it could have grown that extra 2 ft and more.
I plan on coppicing again next year. A lot of my seedling Amorpha I coppiced lightly this year though, just removing a branch or two to which they responded well. So I may have more genetics in different locations to compare with next year. I’ll keep you posted.
In pdf. form. You may have to copy and paste the link into your browser to make it work.
This paper really picks apart the effects of juglone, its production levels, area of effect, and all the possibilities of growing crops under its influence. Written with permaculture in mind.
I especially like their recommendation to plant black alder (Alnus glutinosa) as a nurse crop between your rows of black walnut. Since they’re sensitive to the allelopaths, they die out. But in the meantime you’ve grown poles for coppicing, and leave a whole stump and root system to slowly release nitrogen to the walnut crop -an excellent example of systematic development by filling niches in time.
I look forward to the food forest being more grown up at this time of year -meaning that the the food forest will have more shrubs and trees, making shade, mulch, and cycling more water. I wish I had more of these things right now. But besides being patient, there are several things I am doing to speed up the growth, and make this dream of an established food forest a reality.
First priority is to introduce more species and plants to fill in the huge gaps between the trees. This is what happens in nature where fields begin reverting back to forests from grass. The species in the open field change from grasses, to woody perennials like goldenrod (Solidago species), then to blackberries (Rubus species), multiflora roses (Rosa multiflora), and dogwoods (Cornus controversa), until oaks and the like begin to establish themselves.
By the time the forest trees start to grow up, there is a thick mulch of blackberry and multiflora canes, nicely manured by all the animals attracted there by the multiflora rose hips in the winter, and blackberries in the summer. Nature is not a “Veganic” gardener.
That being said, when I say ‘adding species,’ I do mean adding animal species as well as plant. I have moved our chicken pens across some of the more open places in the food forest, and the effect on the grass has been amazing. Rather than scraggly short stuff, I have lovely swaths of emerald green -nearly a foot taller than the grass next to it; all the green grass growing in the exact shape of the chicken pens.
This extra grass makes more food my rabbit. She can eat exclusively in-system grass and clover, providing lovely “bunny gold” for adding to the mulched beds.
This mulch has been helpful in killing of the scraggly grass under my trees, since to get rid of any sizable patch with mulch I need all the grass I can get.
Mulching to kill grass illustrates the best way to work with these newly introduced species of plants and animals: keep the life moving. In other words, cycle the life as fast as you can, keep all the species of plants and animals as dependent on each other as you can. That is how an ecosystem is built; through the interaction of a lot of species. If you have grass, mulch with it -or feed it to an animal, wild or domesticated. Whatever the case, keep those nutrients active!
Comfrey and nitrogen fixers are most of what I am planting under the trees, along with some Jerusalem artichokes here and there. They compete with the grass masterfully, and at the same time make more biomass.
Whatever I do, there is a lot to be done, not the least of these being to stand back and observe, so I had better get back out there.
We ourselves are part of a guild of species that lie within and without our bodies….. Most of nature is composed of groups of species working interdependantly, and this complexity too must have its synchronistic regulators.”
Rummaged potting soil and dried, dead little seedling roots dangling in the air was a recurring sight in our greenhouse a couple years ago. Whole flats of peppers would have their tops nipped off and the like because of mice.
Poisons, traps, and even some nasty sticky pads lined the floors waiting to dole out death to the offenders, but they were ineffective. The traps caught few mice. The destruction continued. The sticky pads outside our sprouting room caught sparrows which I had a hard time cleaning the nasty goo off trying to save. Nothing worked until we got a cat.
Esmerelda is a small, long haired drop-off cat, but is the best mouser I have ever seen. For a while after she showed up, I would regularly pass her walking up the driveway with a fat vole in her mouth. As I raked out last season’s growth in the greenhouse, her face would be stuffed right in the middle off my work, waiting for a vole to dash from its dinner table.
Now when we plant, the only thing mice bother is fresh squash seeds, but even those are seldom touched. Having made some hanging shelves to keep the squash seeds out of reach, it’s difficult to tell if we have mice or voles at all.
Making friends with rodents is recognizing what voles, mice, and many of the technically-not-rodents like rabbits and ground hogs do for our plants I explained in the earlier post. It also means keeping their numbers in proportion to the rest of the ecology. Artificial trophic system moderators, such as traps and poison, aren’t that effective. What is effective, is encouraging these rodents’ predators.
As a USDA Certified Organic farm, we actually have to submit a written explanation of how we manage trophic levels such as rodent population, and Esmerelda is officially accepted as part of that system.
Owls are major predators of mice and other smaller rodents. Barn owls, which have species across the globe, eat at least one rodent a night. A pair with young captures as much as 3000 per year according to some sources, which would certainly keep about any rodent population in check.
Barn owls are fairly ubiquitous, so the chances of hosting a pair is pretty likely if you have old buildings, hollow trees, or nest boxes where they can raise their young.
In addition to preying on mice, larger species of owls can prey on rabbits. We have a pair of great horned owl on our farm, which we likely wouldn’t have known about if it weren’t for the faint sunlight betraying one of their silhouettes as it ghosted off one evening. We had some young pullets at the time the owl’s were picking off once a day at dusk. The remedy was caging up the pullets earlier in the evening and letting the owls go eat the mice and rabbits.
With this kind of appetite and stealth, great horned owls can obviously carry away some rabbits. Studies have shown even these big owls though also like mice, and that a pair will catch up to a dozen a night when feeding young.
Dogs have a pretty broad array of prey. Foxes prey on mice and rabbits. Larger animals like coyotes can prey on groundhogs, but few of us want those close to our gardens and homes. This is why we domesticated them.
We have a rat terrier, named Daisy -named after the bee bee gun brand. We got her specifically for managing the rodent population, which she does very well. Despite her small size, she also gets possum and groundhogs. This is because we’ve carefully trained her.
We have adhered to the idea that dogs seldom hunt alone, almost always in packs, with one taking the attention, others lunging in for the kill. Daisy has always been taught that if she finds something, we will always come to her aid. If she finds a mouse under something, she barks, we come, and do what we can to move things around and let her get at it.
This is especially important when she beats a very large groundhog to its hole and lays into them. She kills her prey by lifting it off the ground and giving it a whip, snapping it’s neck. As a result groundhogs larger than her are pretty much impossible for her to kill alone. She has always been taught that someone will show up shortly to make the final blow while she keeps it’s attention. She can handle young groundhogs herself.
Our neighbor had a much larger dog they would keep in their fenced garden area at night when the sweet corn was about ripe. This kept raccoons from pillaging the place.
Some might object that allowing an animal to kill anything makes them a threat to their human caretakers. I think this is more a matter of teaching the dog who is a friend, who is a foe, who is above them, and who is below them. This sounds petty among us humans who obviously function differently, but this is how dogs work. Even with animals that could and should be prey for Daisy, we have trained her to not kill.
If our rabbits get out for instance, we sic her on them. She catches them by simply holding them until we come pick them up. She doesn’t pick them up and snap their neck as is her method to kill anything else. The rabbit is a bit slobbered-on after this, but in my experience, catching rabbits alone is seldom less stressful for the rabbit, usually unsuccessful, and simply leaves the rabbit prone to being eaten by a raccoon -because they certainly don’t care about a rabbits quality of life.
In general, I think cats and dogs enjoy a much better quality of life when they are allowed to express their instincts. If we can figure out a way they can do this without endangering us, this isa mutually beneficial relationship.
Across the board, effective ecology creation means making friends with your pests. Sometimes, keeping a balance means making friends with their predators.
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.
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.
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.
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.
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.
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.
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.
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.
“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.
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.
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.
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.