Posted: 24/01/2015 at 15:32
How long has the Sorbus (Rowan?Ash?) been in the ground? Roots will be a major issue the longer it has been there. If you really want to keep the Sorbus (they can be weeds) then I would transplant the Sorbus now before leaf growth and sap rising. If you transplant it from one hole to another and apply feed I doubt it will harm it, assuming you are not destroying lots of mature roots.