I just had about 20 odd tree stumps ground and the person who did the grinding left the debris. I would like to know when this area would be plantable. Could I mix the debris with good soil to be able to plant immediately ? Or ?
former UBC Botanical Garden and Centre for Plant Research Staff
Join Date: May 2006
Location: North Vancouver
Re: Using ground stump debris
I would be concerned about a couple things if you are planting in this media. As the wood chips break down your soil will be deficient in nitrogen. The bacteria, which are partially responsible for the composting process, use nitrogen to build protein in their body. Visit this link for more information. Some people remedy this problem by adding another source of nitrogen, which is a possibility, and easy solution. If the chips are small, the composting process will take less time, and should not cause too much of a problem. If your leaves of your newly planted plants turn yellow, you will know that they are nitrogen deficient.
The other concern is that the wood chips may create too much porosity in the soil, causing water to drain before the roots of the plants absorb it. On the other hand, the added organic material in the soil may be welcomed if you have heavy clay. I doubt that this is too much of a concern, especially if the chips are not too large.
I wonder why the trees were removed. Was it a disease? If so, it is possible that the disease can still be found in the soil and wood chips, and therefore transmitted to your newly planted plants.
With all of these things considered, you are probably safe to plant in this area. Good luck.
I've used wood chips of various species as mulch material on trees, shrubs, and perennials in a number of situations, with absolutely no signs of nitrogen deficiency: though I've read that they can have a very negative effect when used on/near vegetables. Depending on species, the decomposed/decomposing wood is itself a good substrate (witness huckleberries growing from stumps: I've planted blueberries into similar situations with good success). I suspect there is a fairly robust mythology surrounding the woodchips/nitrogen deficiency situation when used as a mulch: probably a lot of truth to it if one were to dig the chips in as a soil amendment.
Thank you all for your replies - but I don't know if I'm any wiser now, but to get back to some of the questions:
I don't know why the trees were cut down, I just inherited the stumps. I think they were those hedging cedars. I didn't dig around but on the surface, the grindings look quite fine but I'll have to make a closer inspection. I have some pictures of the area and some of the other 9' tall trunks (the tops all cut off and I think they're dead) that are left there but my camera won't download the pictures to my computer anymore so as soon as I figure out the problem, I'll post them.
For the sake of continuity, here are the pictures of the area. I think the trees were Hemlock. There is a row on the side of the property with their tops all cut off. I don't know why this was done but I wonder if they're expected to grow back. Is there a way to tell if they're still alive, other than waiting a couple of years ? There are a couple with green lower branches still attached.
Live or dead, these will be ugly forever (IMHO). I'd suggest you cut them down, grub out the roots (check for utilities!) and start again. They were probably removed because they got away from someone a long time ago and were causing excessive shading, debris, neighbor complaints...