Will raising the soil level around a large fir tree damage it or make it susceptible to disease?

I am erecting a tree/garden seat around a very large blue fir. The manufacturer suggests filing the centre with soil and planting out. Does any one have any idea wether this will do any damage to my tree?

Will raising the soil level around a large fir tree damage it or make it susceptible to disease?
Not a good idea. It causes a particular kind of rot near the base of the tree and makes it susceptible to fungus. Integrated pest management issues might be a problem as well.
Reply:Hi Bombie.





The short answer is "yes it will/or could harm the tree".





The majority of a trees feeding and breathing takes place in the fine roots that are found in the top few feet of the surrounding soil.





If you cover over this area with something that will prevent these processes taking place, then the tree could suffocate and therefore become susceptible to fungal invasion - rot.





Anything but a very thin top dressing of "soil" would be consider a very bad idea, particularly with conifers (blue fir for instance) as they are quite shallow rooting.





Mulching on the other hand with composted bark or compost is a great idea as mulch is usually light and open enough to allow gas exchange whilst keeping moisture in. Mulching does NOT cause fungal decay. Fungal decay usually occurs in sick, diseased or damaged wood, not in healthy wood cells... usually. If everyone mulched their trees they would be a lot happier.... the trees that is.... well perhaps the owners too!





If the planter was suspended above the ground allowing air the circulate and not directly against the tree, that might be ok.





Sorry it's not the answer you probably were hoping for, but if you look after the tree it will save on professional care or removal costs and you get a lovely tree to look at.





Hope you work it out and enjoy your seat!
Reply:what????


I am a tree surgeon and most of the answers apart from one from "fair2mid" are all rubbish!


don't plant above the nursery line, this is a visable line near the base on the bark of the tree, darker below and lighter above. This is where the soil level has been and should be otherwise the tree will suffer, it wont't produce suckers but may die of asfixiation.
Reply:It would take more than that to damage a blue fir! There is a remote chance that the tree will put roots up into the loose soil and form suckers - then you can pot them up and you'll have more blue firs.
Reply:The biggest landscaping mistake people make with mulch is piling it too high on the trunks of shrubs and trees. Yes, disease and alas, tree/shrub death occurs.
Reply:way i was taught is never go over 2 feet deep when building soil up around a tree-if in doubt fill in within 1 foot at base of tree
Reply:None at all.