Further arrests have been made after a man in his 20s was stabbed in the neck and shoulder.
Six people have now been arrested in connection with the assault which happened in Harbour Street at about 3am on Sunday, May 12.
Police have been appealing for witnesses to come forward and reviewed CCTV.
As a result of their continued enquiries they searched seven properties yesterday in Northdown Road, Cliftonville, South Eastern Road, Inverary Court and Dane Crescent in Ramsgate along with Dane Road, Charlotte Square and Beatrice Road in Margate.
During the planned search warrant, three teenagers, aged 19, 16, and 18 - all from Ramsgate - were arrested. They have all been released on bail until August 7.
It comes after three other men, all aged 18, were arrested on suspicion of assault on Sunday, May 12. They remain under investigation.
Senior investigating officer, detective chief inspector Chris Greenstreet, said: "We remain committed to tackling knife crime culture and are determined in our efforts to remove dangerous weapons from our communities.
"We will continue to take robust action against people who choose to break the law to ensure towns like Ramsgate remain a safe place to live.
"I would like to thank all those witnesses who have come forward so far following this incident and encourage anyone else with information to call us."
After being taken to London hospital with serious injuries, Mr Grainger is now recovering at home.
Those with any information are asked to call police on 01843 222289 quoting reference 46/89866/19.
Alternatively, you can call the independent charity Crimestoppers in Kent anonymously on 0800 555111.