Raised beds around trees

Any thoughts, suggestions or warnings about building a raised bed under a locust tree? The trees roots are very close to the surface and are actually showing in the lawn in low areas. I don't want to take the chance of damaging the tree with the lawn mower. The idea was to build a square bed about 8 foot square and 24 inches high with a cap rail for seating around the tree and filling the low spots in the lawn with soil and reseeding. Any advise would be appreciated! (please remember- you are talking to a novice) :)
Thanks!

Don't even think about it! Just mulch the area, insert some small plugs of shade-tolerant plants, minor spring bulbs, etc. between the roots, and you'll be fine. Never raise the soil level around the trunk of a tree.

Guy S.

Thanks for the info-care to further educate a novice? I have read that raising the soil level can "choke" the tree, but I have seen many trees with raised beds and planters around them and they seem very healthy. (a picture of one on this website and one next door that looks really nice for example). Also, won't constantly running over the roots with the mower cause damage. Some of the roots showing are quite a distance from the trunk and I don't think my hubby will let me mulch the whole back yard. Also one clarification-much to my embarassment- I must admit that it is a Maple not a Locust. I do have a Locust, it just isn't the tree in question!

Maple, Locust, whatever -- don't cover the trunk bark with soil, or bury much of the root zone by more than an inch or so. Trunks are not adapted to fight off soil fungi like roots are, and you will be starting a decay process that will kill your tree eventually. And the roots are shallow due to the density of your soil -- if you bury them they will suffocate.

Tell hubby that yes indeed you have good news for him -- all that grass he used to have to mow is history. Then call up the local power company or your arborist and have them deliver (usually for free) a couple of truckloads of wood chips. After you have killed the grass and weeds with Glyphosate, spread the chips about 2-3 inches deep over every part of the former lawn that has exposed roots.

Plan B = cut down the tree and keep mowing all that grass for no reason.

Guy S

So question, I have done just that(put raised bed around a tree) What do you suggest I do. Can it be corrected without removing the beds completely.

I was taught as a young child that the most beautiful thing about a tree is seeing it where it meets the earth.
Putting weight of any kind on top of a tree's roots is not good, especially stones and benches. Sooner or later it will harm the tree. And, gardens grown around trees take the nourishment and water from the tree.
Many people have killed their trees this way with too much soil on the roots or too heavy stones.

This is not directly related to the posters question, but I've seen ample evidence of pretty significant soil build-up around a tree without harm, as long as it is kept a few feet away from the tree. In some cases I've seen where a few feet of soil have been laid over the root zone, seemingly without harm. The tree in the pics is an old Oak that was big before the lot had a commercial building and parking lot built. This took place over 20 years ago and the tree doesn't seem to be any worse off.

http://img.photobucket.com/albums/v145/maackia/Woody%20Stuff/Deciduous%20Trees/HPIM2220.jpg

http://img.photobucket.com/albums/v145/maackia/Woody%20Stuff/Deciduous%20Trees/HPIM2221.jpg

http://img.photobucket.com/albums/v145/maackia/Woody%20Stuff/Deciduous%20Trees/HPIM2219.jpg

I too have seen many instances where trees have planters built directly around them but I am not willing to take the chance of killing the tree. SO Hubby and I have decided to compromise-no planter around the trunk, just a few shade tolerant plants and we will fill the low areas out in the lawn with a inch of nice compost and grass seed. Thanks for all the info ! :)
KD

Some trees are able to adapt, often by developing a secondary adventive root system (which is much weaker structurally than the original one was). Filling above the roots is risky, depending upon how much area is involved, how deep the fill is laid, soil texture, compaction, and tree species. Some floodplain trees can adjust if the fill is added incrementally, like siltation would do along a river.

Regardless, I would never raise the soil around the root flare (base), and don't even pile mulch there. The trunk bark has little defense against soil-borne pathogens that can spread in a constantly moist environment, and you are asking for major trouble.

Ghia, if I were you I would remove the fill, relocate the plants, and mulch the area lightly (2-3 inches deep) -- sooner rather than later. Then, if you would like to plug in some very small starts of plants between the tree roots at the original grade level, go for it.

Guy S.

I have personally severely damaged a locust by rasing the soil. A Gleditsia, in Colorado no less.
I've been told that those new adaptive adventitious roots are more apt to girdle the tree.

And then there is someone who composts and tills under his pine trees and seems to get away with it. I wish he would stop making exceptions to spit on common arbor-knowledge.

KD- depending on what you think of Hedera, the less vigorous cvrs can be very nice dry-shade groundcover with no mowing. Dry again: some folks use Aogopodium http://davesgarden.com/pf/showimage/40247/ or Ajuga http://davesgarden.com/pf/showimage/20715/ to great use, but these should be watched and controlled.
I've experimented and failed with so many shade groundcovers it is embarassing.
K. James

OK I was just browsing but I have seen those roots of the Ponderosa Pines growing up in my raised beds. Yes I keep the soil off the base but the trees that are covered with the raised beds are thriving where the natives are not. I do admit that the irrigation is responsible but what is wrong with that rich soil allowing the aventitious roots to suck off the nipple of the compost placed under that tree. Especially when that tree is surviving in only the top 10" of glacial moraine. My beds are admittantly only up to 8 years old but the trees are very happy. I am not an expert but I am a gardener who wants the soils to produce more than the native species that barely survive every droughted year.

What about the trees in the flood plains of major rivers that get buried in silt and other composting material every spring. They grow up and become mighty monarchs of the flood plain. Nature does this often and only if you live in the alluvial silts of the midwest does this suffacation occur. After all spoiled children have a hard time adjusting to challenges in life. I respect your advice Guy and know that you do it the way it should be done. But nature often does the imperfect and species survive and THRIVE.

This message was edited Jul 20, 2006 10:55 PM

8 years. If they were going to die, they would have done it by now. It is funny how the damage can appear several years after the activity. Shed some light on that if you can, Guy.

Platanus trees also don't like their roots being tilled/covered. They will regrow new ones very fast, but a lot of twigs will die...

I have to wonder how feasable a spot-buildup would be. Put down small pile of compost/soil every few long feet. Let that settle a year or more and the tree roots come up. Add more in following years. Idea or nonsense, my esteemed colleagues?
K

Those are made to survive that, Steve. Like the knee-endowed Taxodiums. Isn't Q. bicolor one of those as well? And it is not a continual buildup always- isn't it also subtractive?

If you look at any antiquity you will see that the valleys of the rivers is on a constant rise. My glaciated valley has continually risen after the last glaciation. The trees have changed but observing the old ones IE a forest I visited in The Ross Cedars in Montana were deeply buried in sediment over the crowns of their bases. (estimated ages of 130 to 180 years old) Though I believe that each different species of tree has its own limitations. White pines I crawled in and out of as a young man showed the burned monarchs had over its crown many inches of sediment. This accumulated loam/sand that buried the big ones in what we called a climax forest were the ones left after all the fires and logging.

This message was edited Jul 20, 2006 11:10 PM

Good point.

As I mentioned earlier,

Some trees can adjust to that, and may even thrive in it, if they evolved to do so. But such natural depositions are episodic over a long time period and occur in nature only in flood plains around the species that can tolerate it. Why do you think such flood plains are so depauperate of species? Look for upland trees there and you'll come away empty because any that try to grow there are killed by deposition or related root problems. And James is right, there is some downcutting as well, but it happens only as the channel becomes entrenched or meanders. Then the trees along its banks collapse and become driftwood, lodging at places in the channel and perpetuating the meandering via flow alteration. The silt eroded from the caving banks is deposited downstream in the same floodplain, either next to the channel as the stream flow is slowed by riparian vegetation, slowly raising natural levees, and/or over the entire flood plain during major events.

Anyway, placing a few raised beds under a tree canopy is not a big deal as long as you do it in moderation. Some roots will be killed while others grow back into the raised area. But I would never place much fill, or even deep mulch, against the trunk of any tree. I've seen way too many fine old trees die from that -- maybe not the first year, but within a decade or two as the compromised root system slowly fails and the constantly moist bark is invaded by soil pathogens.

Now y'all go do whatever ya wanna do, and good luck!

Guy S.

Thanks Guy oh Great One. I do agree with everything you say cause I am just a humble follower of you. Your humble servant Steve. Montana must be different cause all of the flood plains are full of multiple species, Aspen, Doug fir, Ponderosa, Cottonwoods, Dogwoods, and various Junipers. Yes erosion is a problem but since flooding is rare here due to all the hydroelectric dams we have little change in the river bottom. Besides we have a unique soil stabilizing event here in Montana. In the 30's and 40's everyone dumped their car along the banks to keep the river in check. Oil, Tranny fluid, Heavy metals, and what ever else is slowly seeping into the water supply. Great Idea huh?

Sanctioned by the Army Corps of Engineers, of course. ;>)

Whew! And I was worried that no one would answer my question!
Guy-don't worry, I promise not to put anything too close to the root flare(I am really sounding like a gardener now) and the spots in the lawn are pretty small and wouldn't take more than an inch to cover. My dream is to have a woodland type shade garden filled with hostas and other shade loving plants so doing anything that would jepordize the tree is out of the question. It is a main source of shade and I need to add more trees not kill the ones I have.
K.James-I like the ivy idea, but until now only have it containers because I read it can be very invasive which scares me a little. Although my only attempt to grow it was in Oklahoma and I didn't have much luck. Go figure-everyone is trying to kill it and I couldn't keep it going.
Remember guys-I am a novice so anything info I get from you and this site becomes law! I really do appreciate all of the information.
Thanks! KD

If anybody should ever go to Freeport, ME, there are 2 things to see there. One is the L.L.Bean store. Must be something, everybody goes. The other thing is a natural sandy spot called the Desert of Maine. It must be a real desert because "the judges" on Jeopardy gave credit for the question "What is the Desert of Maine?" when Alex said "It is the farthest east desert in the United States." So that makes it official as you get in this culture.

The Desert of Maine (hereafter, the desert) is a place where the last glacier to take the soil left a huge puddle of sand. Over the eons, trees and grasses etc. encroached on it and completely covered it. Then the Europeans came and took off the vegetation and tried to farm it. Well, once the vegetation was stripped, the ENE winds in the winter pushed it one way and the WSW winds t'other. Soon it was not farmable, but it makes a dandy tourist attraction. If you walk out into the desert, the edges are sand dunes many feet high and you walk among the tops of oaks and other hardwoods. Pines don't seem to take to getting 1/2 buried, seems to me there are only hardwoods 1/2 buried.

Personally, I think raised beds are a bad idea if only because in a couple of years the tree roots have filled the raised area, and rob any nutrients and water they can. Few perrenials can compete with a tree. I think root compaction is a quicker to kill a tree, but that's a whole other story.

If you go to the page 'Nature', you find this paragraph: "Nature, Diverse and Spledid"

"The Desert of Maine and it's surrounding forest have remained a natural haven for Maines indigenous Flora & Fauna. See living trees half covered in sand. Puruse the various nature trails and see wild flowers, mushrooms,wild blueberries and many other varieties of nature's wonders... "
http://www.desertofmaine.com/desert.htm

We have large live oaks in the Bonnet Carre Spillway that have been there since the Spillway opened in 1930. When the locks are opened and tons of water flow through the water leaves a sediment. However, I think because this happens only once every ten or so years the alluvial soil is deposited a little at a time and the tree can adjust to it.
I am watching a gorgeous magnolia die a slow death because my neighbor piled soil on the roots and built a flower bed. It has taken a few years but it will soon be no more.
The rule of thumb is usually no more than two inches of soil added per year.

Oh please, please, please do not plant ivy at the base of your poor tree! Forgive my empassioned plea here, but little makes me sadder in mature gardens than to see some gorgeous old tree smothered out and distorted by overgrown ivy. People like the way the ivy looks growing up the trunk, but it will get out of hand quickly and I really think you'll regret it later on. I could be wrong, but I had to speak up :) I'm taking a deep breath now. Relaxing. Backing off :)

Take care,
Jacci

In defense of the innocent (hah!) Ivy, there are cultivars out there (most of the popular ones, really, now) that are less vigorous by selection. The ivy society picks one each year to be an ambassador of the Hederas that says "We're not all villains, see how I grow?"
I grow one such guy who does not grow more than 1/4 inch a year. Others make a moderate-speed groundcover, but never seem to figure out how to climb, or to my personal disdain, are slow to root. They are also suppressed by Colorado's lack of rain, and most will die if they are not irrigated.
(And to spare myself of stories about the voracious tree-eaters out there: I have seen it and done that battle. But I happen to like hedera)
K. James

So, kind of along these same lines, I have another question pertaining to raised beds around trees. If it's on topic it's not thread hijacking, right? ;)

Let's say that the Master Plan is to eventually have a large berm with about 7 evergreens, maybe 3 deciduous trees, and a goodly number of shrubs of varying sizes, filling in spots with perennials and annuals. But, you're starting from scratch, money is the limiting factor, and you need to accomplish this in stages.

I'm assuming since the evergreens and other trees are the "bones", these should be planted first. My question is, "Is there anyway to avoid a huge, mostly-empty berm planted w/ only 7 smallish evergreens"? The huge, mostly-empty berm is my concern. Why not put a huge sign out that says "Hello weeds! Welcome to your new home!"? I'm not interested in fighting that for years until the whole thing gets planted and fills out.

The only thing I can come up with is to plant each evergreen in its own little berm. I'm guessing maybe 3 ft high and 8 ft around? Just a guess? Then plant the deciduous guys in there own little berms a bit later (2 years). Give them some time to grow and fill out (5 years) and then berm the spaces in between and plant the shrubs, etc. Would the berms that came last kill the trees? They would be in the space outside the 8' wide berm the tree was originally planted in, and would come about 5-8 years after the tree was originally planted. They'd kill the trees, wouldn't they? Thoughts? Insights?

Sensei?

Your thinking is right to plant the soil structure as the total package. IE one big berm then the trees. Then weeds are discouraged by mulch and compost to start to feed the soil as the plan is purchased. Oh I never plan on a bed being unchanged for more than 5 years. So build a sunny bed and propagate the plants until the forest is established and then move them when the canopy changes. I would not add soil to the between the berm locations. Start with what you want.

Hi Huga ;-)

I agree with Steve, always do the grading first. You can sew wheat, oats, annual flowers, or whatever on the berms (actually, mounds -- true berms are more like terraces) until you get around to doing something more permanent.

Guy S.

I figured as much.

So basically, the first 2 years I'd just have to buy the dirt alone and throw annual seeds on it to discourage weeds. Budget blown right there for anything else. Hmmm...That much mulch would be extremely expensive, so I'm not sure about mulching the whole thing while it's empty. Then a tree here, a tree there until it's done, eh? Sounds like a good exercise in patience. Also sounds like I don't want to start it until I'm sure I'll be at that house for at least 10 years, LOL :)

Thanks for the input :) "If you're gonna do it, do it right", right? ;)

Y'all take care,
Jacci

I have gathered mulch from tree chippings in my area. Just look at the sides of the roads where utilities have been installed, or where developments have occured, or go to a pine forest and collect pine needles. All free. If you use wood chips add a little cow manure to help break down the carbon. Grass clipings work well.

I am actually going to disagree with Sofer and Guy here. In a perfect world where money isn't the factor, I would do all the grading and mulch first like they recommend and plant the trees. Since you said money is the factor, I would plant the trees first like you describe. I would just make the individual tree mounds as wide as money allows so the roots never get too close to the mound's edge. Then when you fill the areas between the trees with soil, make sure you mix the new soil with the edges of the tree mounds to eliminate any transition problems. That is the only way I see it done if money is the problem and you want to get your trees in first to give them time to grow. Just make sure the soils that you buy are very similar in composition and that you get the height of the initial mounds correct.

Bill