Root systems on trees go two to three times longer than the drip line of the tree. Changing the grade around a tree by three inches, may kill the tree

Even if the grade change only represents 20% of the overall root system area? What type of risk are we talking about? This is the only shady spot I can put the swingset.

I would say it would be detrimental to the tree also.

BUT, having said that, I did the same thing about 6 years ago, before I learned that I shouldn't!

Ironically, same tree, sweetgum. Except in my case, the retaining wall was about 4 feet from the trunk, and at the deepest point about 2 feet deep! (The tree was on a steep grade). From what I know now, I probably smothered close to 1/3 of the root mass!

The tree's doing just fine, thank you!

Cheers!

You will undoubtedly impact the tree. The question is, how much, and is it a reasonable risk? Trees lose roots when things like this happen, but they also, over time, regain some or all of their root systems. I'd say, go ahead with your plans, but minimize any actual large root cutting you do if possible. Then, take extra good care of the tree in subsequent years, paying attention primarily to water, seeing that it deoesn't get too dry.

+oM

I agree with +om.

If you think it advisable, and have the room, you could start (or buy) a new tree now, growing it on into larger and larger pots over the next few years. If it becomes obvious that the sweetgum was badly damaged by the disturbance of its roots, then you have a replacement on hand. Might I suggest something like a tulip poplar? They grow fast, and are of a similar growth pattern to sweetgums - at least the ones here seem to be. Maples are another possibility, although their roots can become problematic for surface growth and for greediness. Unless the sweetgum is one of the non-fruiting clones, you probably are weeding babies out of flower beds, so could pot up several of those as well - I suggest potting up several, so one may survive....

Thanks for the advice so far. Keep advising if you feel like you have more to add....I love learning about this stuff.

Some follow up questions:
What's the best way to water a tree. I've read that I shouldn't just put a hose at it's base because this can attract insects and diseases, but using a sprinkle doesn't seem to get the water deep enough. A neighbor has one of those sub-terranian spikes that send water underground at the drip line of the tree. Is that the best option? How long should you water for?

Why wouldn't I just buy a 6' - 10' tree as a replacement? Because of cost?

What do people usually do with all of those annoying spikey balls that the sweet gums drop in the winter? They don't decay quickly. I tried mowing with a bag mower, but is was mostly useless. Raking wasn't much better and tore up the grass because the balls are embedded in the grass. Then I took the whole family out and spent several hours picking them up by hand. We have 6 of these trees. WHAT A PAIN! Is there some type of garden sweeper or something that can make gathering them up easier?

Thanks again.

You might look around for some soaker hose, the kind that weep, and lay it around the tree in a spiral, starting outside the drip-line and moving in, or vice versa, whichever works for you. They are easy enough to shorten if the one you can find is too long; buy a new hose end of the correct type (male or female, and for the correct hose diameter), cut the soaker hose where you want and put on the new end, with the cap from the old one. New caps may be bought also, and an end can be put on the piece cut off, so you have 2 lengths. How much hose to use depends on your soil - put the coils closer together on sandy soil, and space them wider with clay. You just connect the garden hose to the end, set the flow rate so the soaker hose is just dripping, and leave it on - overnight, all day, or just several hours, until you have watered the entire root area - it will depend on the area and soil type to know how long - dig down and see after you set it up and see what the soil looks like.

You can buy a replacement tree - there's no reason not to. I was thinking of saving some money - if you can grow a tree out to a 15 gallon nursery pot, you are looking at a cost, as of now, of about $80-250 dollars, depending on the location you live in and the variety of tree. BUT, you do have to want to grow it on, and be willing and able to re-pot it as it needs, so buying one may well be the best move for you. Since this is hypothetically going to be needed to replace the sweetgum, I figured you might have a spot to plant it elsewhere on your property if it wasn't needed. But, it was a suggestion, not anything more, that you grow your own.

I wholly agree about the 'gumballs'. I can't stand them, pull every seedling that sprouts in my flower beds, and wish the trees edging my yard would die, or at least, go away in the late summer when the 'gumballs' fall! I think one of the yard vacuums MIGHT collect them, but am not sure, and you would have to be quick to collect them, before they got tangled in the grass.

I think you will be OK. It is not a good idea to move a lot of soil onto the rooting zone of a tree. But your tree is young, you will not be covering that much of the area, and much of the area you cover will not have that much new soil. I think the risk that you will really damage this tree is 10% or less.

Also, some kinds of trees are more sensitive to this kind of thing than others--sorry, I don't really know specifically about sweetgum. But my guess is that a tree like this that frequently grows in bottomlands subject to flooding and silt deposition, will be more tolerant than some others.

Go ahead and don't worry.

--Spruce

I live in prince george bc and i am currently building a large raised flower bed around two old mature spruce tree's. I had to chop a few large roots out in order to put in the landscape ties. Is there anything i should give to the tree to help them cope with the stress from cutting the roots?? There is alot of them but i only had to cut about (5) 2-3 inch roots back. Now my big question is... I am filling in the bed with black earth top soil about 18-24 inches deep. Is this going to hurt the tree's or kill them. What would you advise i do. Thanks.