I have an ornamental cherry tree approximately 30 ft tall, which is now close enough to my house that I could touch it from my window. I would like to keep it , but am concerned it will damage my property. Do I need to cule, or can I have a good cut back to halt root spread? Your advice would be grately appreciated. Thanks. Mick
My advice is to remove the tree, unless it were a small or dwarf form, which, if yours is already 30 feet, doesn't seem to be the case. Cherries, ornamental or otherwise, send out extensive surface roots which get pretty large, as well as having one or two major roots which go down a long way to keep the tree stable. Without knowing the variety of Prunus you have, there's no way of knowing just how big it is likely to get, although I realise it is not a fruiting variety.
Recommended planting distance from any structure with footings/foundations (including walls and outbuildings, but particularly houses) for non dwarf varieties of trees generally is around 40 feet, more for large trees such as, say, Eucalyptus gunni.
You should be able to save both the tree and the house foundation. Although 5 meters is a bit closer than desirable, the root hazard at least can be dealt with. The method below is high labor and can be expensive, but depending on the value of the tree to you, it's a possible solution.
You will need to dig a trench between the house and the tree, close to the house foundation. (if your house has any kind of drainage system or termite proofing near it, you'll need to find out where that is and trench outside that area) You want the trench closer to the foundation than to the tree trunk to minimize root damage leading to instability.
The trench should be at least 18" deep (if you were not in heavy clay, it should be deeper - 2-3 feet) but can be quite narrow. It should extend at least 20-30 feet in each direction from the point on the house foundation directly opposite the trunk. This will cut all roots approaching the foundation. A ditch-witch (often available at rental places) will make this job much, much easier than trying to do it by hand! Or you could hire a landscape company to do the work.
Then insert some kind of root barrier into the trench - copper treated landscape fabric, heavy grade plastic sheeting, etc and refill the trench.
Make sure to give the tree some extra watering for the next year or so since it will have lost some portion of its root system.
Be aware that this root pruning and barrier method will not help with the other potential problem of trees close to houses - toppling.
You probably shouldn't have a cherry tree that is that tall, I would contact an arborist to see what they think, if you insist on some DIY trimming, always trim right after a node, you will probably have to cut some benches that are much thicker than you would normally trim, so get some sealant, and work in the fall to early spring.... Check out one of the many great articles on training fruit trees.