There is a tree of a grand size in my yard, at least 50 feet tall. It dominates the area, creates some shade, a ton of leaf liter, and some habitat for birds. It definitely plays a special part in the land.
There's just so much space under the crown of the tree, especially within a 10 foot radius of the tree that's not being utilized for anything other than grass. I'm really trying to create a bang of biodiversity and richness on my yard, and I don't have all that much space (crowded suburban area).
Now this old tree has very thick roots and I'm thinking the soil is pretty thin with the kind of extensive rootage it has.
Could anyone suggest to me some options for shrubs, cover, soilbuilding vegetation or anything else that would work on top of thick tree roots? Is it possible to load up mulch on top of the roots to build up some organic matter, or would that be harmful?
I would suggest you put in a series of raised beds, herb spirals, and plant shade-loving plants all around the base of the tree. You will not damage the roots by adding topsoil, plant a few good nitrogen-fixers like the Siberian Pea Shrub, some Nettle and Dock. Find out where the sun will be strongest and utilize the vertical space in the area. Jerusalem Artichoke will grow well at the base of a tree...hope this helps!
I've seen raised beds created around large trees in a wheel and spoke pattern, as in strips of beds radiating out from around the trunk. They could even be curved for sort of a spiraling pin wheel shape (this appeals to me way more than straight beds, but do what you want). This leaves path space between each bed. It's crucial to plan for access so that you don't need to step on your beds to harvest things - make the beds no wider than you can easily reach to the middle from the path on either side (about 4 feet at the widest). You can have the more shade loving things (violets, ferns, giant soloman's seal, nettle) growing in the end of the bed nearest the trunk, and more sun loving things towards the end, especially on the south side (if you're on my side of the equator, the north side if you're south of the equator). I personally wouldn't plant anything you need to dig tubers from beneath your tree, you'll risk damaging the roots when you harvest, and fighting the roots would just be a pain. And as far as I know, Jerusalem artichokes do best in full sun.
If the tree is on a slope, consider mounding up dirt on the down hill side (a swale) and plant stuff on top of the mound to hold it in place.
Image if that great leaf litter you mention had been left to fall and lie at the base of that big tree all these years. The tree would be self composting it's next new layer of soil
If you can, do find out what type of tree it is.
Then you can understand the ideal conditions this tree prefers and better match what you plant under it to the same conditions.
However, if it were me I would add compost or maybe it's own leaves broken up as a living mulch back over those roots.
Hm ok so how I understand it, within 10 ft (the general radius of exposed roots) its a bad idea to cover it with any soil. I don't think leeks (tubers?) would be good in the immediate area around the truck because the root competition would be insane, maybe past 10 feet it would be ok.
I think the main reason I want to put something there is that its very bare looking and very, bleh, in the winter. So is there any ground cover, insectoriess, bushes, that might be able to take those kind of conditions? (I wonder how it works in the forest)
@ Travis Philips, im in zone 6
I would say you might get away with a good layer of mulch around the tree but make sure it is fluffy enough to allow the tree to breath.
Then if you want to build up say one section of planting bed with soil and compost to plant something at least several feet out from the tree, make sure not to cover more than say 1/4 of the way around the tree in any one year. The tree will send up surface roots into the new bed, beware of this so I wouldn't advise planting anything that you have to dig out like potatoes or carrots. Anyway, it is kinda like when having to move a smaller tree, you are only supposed to cut a portion of the roots at a time to give the tree time to grow new roots to support it before cutting the rest away. So, only bury a portion of the area under the tree at a time so the tree can send up new surface roots into the beds so it will be able to breath. Some people like to build 2' deep planter beds all around under a tree canopy and they go filling in the entire root zone under 2' of dirt and the poor tree dies of suffocation. so, a little at a time if you want the tree to survive and I'd avoid piling up dirt right next to the trunk but a little mulch or compost to improve the situation for the exposed roots might be appreciated by the tree provided you don't go too thick. As noted, a little each year so the tree can adjust.
The not about water is important. If you start over watering the root zone of the tree, it might experience problems it isn't used to like fungus, root rot, or pests. Be sure to choose things that will be compatible with the trees water demands.
I have a huge Oak out in my front yard. About 8 foot out from the trunk I have a half circle of Aloe plants on one side and a half circle of potted ferns. There is a drip line feeding the aloe and ferns. When we first moved in we hired a tree service to thin out/open up the tree a bit. It's what they call a safety trim here to allow high winds to blow through easier and hopefully avoid taking down the tree during a hurricane. It made it much easier to see up into the structure of the tree and gave the front yard a much more airy feel. There are also some palms, azaleas, pineapples, and other assorted plants growing under the drip line of that tree.
Zone 6 ... how nice. I maintain a place in zone 5 and zone 7.
Asparagus is great. I can never say enough about it. Grows from seed and grows well for me at both places.
I don't think leeks (tubers?) would be good in the immediate area around the truck because the root competition would be insane, maybe past 10 feet it would be ok.
So is there any ground cover, insectoriess, bushes, that might be able to take those kind of conditions? (I wonder how it works in the forest)
I've seen large clumps of wild leeks growing well within 10 feet of several mature trees driplines, including maples. This was in a 'wild' section of forest.
As for ground covers, I've also seen wild ginger (Asarum canadense.) growing under maples in the wild, and though not a ground cover, growing amongst them were small wild onions of some kind.
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