Ellen McDaid came out of hospital after a stress-related illness to find the memorial to son Jonny Smith on Maybury Road splattered with mud and grass.
Council bosses apologised for the gaffe during efforts to tidy up the site for the family before dispatching a team to clear up the mess.
Jonny’s brother Callum Smith, 25, said: “Mum visits his memorial every single day to keep it looking nice for him, which we have done for three months now.
“She came out of hospital only to go to the memorial to find that the workers who were cutting the grass back had chucked all their soil and rubbish all over our memorial for Jonny.
“Every flower is ruined. It broke my mum’s heart.”
Ms McDaid was rushed to hospital with a suspected stroke last week during a long weekend in Berwick-upon-Tweed.
She was later confirmed as suffering Bell’s palsy and is still suffering paralysis down her right side.
Callum said: “It’s been a really hard week this week. The realisation that it has been three months now hits home.
“On top of that my poor mum, due to all this stress, ended up in hospital, in there bed-bound for six days because she can’t take a break.
“Her mind never rests – the constant feeling of guilt because there was nothing she could do to help Jonny.”
City transport and environment convener, Councillor Lesley Macinnes, said: “After meeting with family members we have been carrying out work to improve the area, including cutting back grass and weeds next to the footway.
“Unfortunately, during the course of this, some debris was inadvertently scattered onto the memorial.
“On being made aware, we returned to the site immediately to restore it to its original condition and make additional improvements, with which family members were satisfied. We apologise for any distress caused.”
Jonny, 29, was killed when his car burst into flames in a horror smash caused by a stolen car speeding on the wrong side of the road in May.
Police are still looking for the driver of the stolen Audi that caused the crash. Anyone with information can call police on 101.