GUNILLA MAPLE

Question: Is there any harm in placing more soil around the drip-line and trunk of my maple that is about four years old?

responder: Alison O'Connor, PhD  Replied April 03, 2024, 6:05 PM EDT
response: Hi Larry,  I wouldn't recommend a heavy layer of soil - it already looks like the tree might be planted a little deep. Have you added soil in the past? A better option would be to just use wood mulch chips in a layer that is 4-5" thick. Mulch still allows for oxygen infiltration and water movement to the soil and tree roots.   Using soil can create a soil texture interface, where water and air may not move through easily.

responder: The Question Asker Replied April 03, 2024, 6:28 PM EDT
response: Last fall I did add about 6" of soil from the drip line toward the tree trunk because it was the lowest point in my surrounding landscape. How far out from the trunk of the tree should I remove the soil, at the trunk area should I expose the top of the roots? Then should I put mulch away from the trunk to the drip line? What are your thoughts on using shredded redwood or cedar mulch? Thanks

responder: The Question Asker Replied April 03, 2024, 6:31 PM EDT
response: Last fall I did add about 6" of soil from the drip line toward the tree trunk because it was the lowest point in my surrounding landscape. How far out from the trunk of the tree should I remove the soil, at the trunk area should I expose the top of the roots? Then should I put mulch away from the trunk to the drip line? What are your thoughts on using shredded redwood or cedar mulch? Thanks

responder: Alison O'Connor, PhD  Replied April 03, 2024, 7:22 PM EDT
response: Hi Larry,  Tree roots extend 3-5 times the width of the canopy. In a perfect world, you would probably scrape back much of the soil you applied. You could easily put 4-6 inches of mulch down without concern, since it's more porous. But this may not fix the low spots.  Should you remove any soil, be careful not to damage the roots during that process. Some trees are more tolerant to being planted deep or having their roots buried, but I can't find any studies where ginnala maples were used.

responder: The Question Asker Replied April 03, 2024, 7:53 PM EDT
response: What are your thoughts on using shredded redwood or cedar mulch? How far from the trunk should the mulch start?  The picture with the roots exposed also has fine hairs running out to the drip. should that be covered with dirt before the mulch? Thanks

responder: Alison O'Connor, PhD  Replied April 03, 2024, 8:37 PM EDT
response: Hi Larry,  Shredded hardwood (gorilla hair?) sometimes mats down too much and prevents water from reaching the soil. Cedar is fine. The cheapest mulch - and most readily available - are arborist chips. The free stuff you can get from the city or from tree care companies. You can use that as the base and then top with a colored mulch of your choice.  Keep the mulch 6-12 inches from the trunk of the tree.   No, you don't need to cover the fine roots with soil before mulching. They will happily live in the mulch. They are likely on the surface because of the change in grade from the previous application of soil.  Also, if you're willing, remove the landscape fabric below the tree. The pores clog over time and don't allow for proper oxygen and water exchange into the soil.