The following question and answer were contained in my Growing Concerns column on December 24, 2005. In putting together this answer I came across some facts that weren't essential to the article and so for purposes of maintaining a reasonable column length I didn't include them there. Yet they were interesting enough that I wanted to share them with anyone who was interested enough in that topic to follow it further. So here they are, appended to the Q&A.
I also ended with a question of my own on this topic, included below. If you can shed any light on it, please join in.
The question was:
My neighbor's daughter wants to plant some of the zebra grass (Miscanthus sinensis 'Zebrinus') I gave her on top of the ground-up stump of an ash tree as soon as the village grinds the stump. Do you think the grass will grow there? If so, how should she prepare the soil?
In Growing Concerns 12-24-05 I wrote:
If it's sunny and the soil is well drained a Miscanthus can grow there, but not in the what the grinder will leave -- nearly pure sawdust and wood chips. Dig out the woody material at least a foot deep and replace it with proper soil.
Mound the soil to plant the grass a few inches high in anticipation of settling, which is unavoidable as the wood that remains in the ground will lose mass in decomposing. If it was a very large tree so that the grinder left intact a wide section of the trunk base below ground, shift the ornamental grass so it sits beyond or at least at the edge of this shelf, where drainage will be better than at its center.
Additional information just for this forum:
Here's another way that the gardener can deal with the underground, post-grinding remnant of a very large tree.
A very large tree trunk, even after it's ground down 8 inches below soil level, may still be several inches deep across the entire trunk diameter. This may form a wooden plate beneath the new plant that can seriously impede or stop the drainage of water through that soil.
You should remove the wood chips and sawdust from above the plate, so that you can replace it with good garden soil. While you have the remnant of the trunk exposed or nearly exposed, drill several large holes in it with an auger -- use a gas powered drill because most electric carpentry drills aren't up to the task of drilling through moist wood and soil. Drill with care as rock and other buried items can throw the drill handler for a loop if he or she is unprepared. Drill until the waste material being raised by the drill's screw is soil, not wood.
Now water that would collect on that wooden plate will fall through to lower soil levels. The roots of your new planting won't rot in trapped water. Also, the remainder of the tree trunk will rot more quickly since more air and water will move through the soil around it.
A question, related to tree stumps left in the ground. Some products are available that claim to speed up the deterioration of a stump. Have you had any personal experience with these so that you can you tell us how much sooner a stump rotted away with their use compared to stump(s) you didn't treat?
Planting where a stump is ground out, continued fr
1 reply to this topic
Posted 03 January 2006 - 06:08 PM
Two years ago we had an old multi-trunked silver maple removed in late winter. The stump was ground to 6-8 inches below grade but plenty remained. We knew the tree needed to go but the empty space in our landscape revealed an unsightly view. We didn't want the shade replaced but the hole in the "wall" needed immediate repair. It called for a large shrub that offered at least two seasons of interest. We had an eight year old doublefile viburnum in the front yard that was getting more shaded each year. In early spring, before budbreak, two people and a hand cart moved the shrub with a sizeable root ball. To ensure a successful transplant the site was improved. The wood remains of the stump grinding were removed. A mattock and root saw were used to allow water egress (instead of a drill). Soil that was part native (clay/loam) and part 50/50 mix was added to replace and then slightly elevate the grade. The root ball was positioned not directly above the old stump but slightly off to one side so some roots were in native soil and most were above the initial spot. The bush was carefully replanted, watered well, and monitered. It bloomed a couple months later and put out good growth. This past spring the bloom was exceptional and the bright red fruit in September was memorable as well as a bird magnet. We found that we could successfully replant after tree removal as long as care was taken to make the site suitable for the replacement.