All 930 employees had a two per cent rise in April. This was increased to four per cent for permanent staff aged from 21 on the lowest wage - around 11 per cent of the permanent workforce.
The company said it "is not in a position" to pay the Living Wage (£7.65 per hour) across its business yet. Queen Elizabeth Olympic Park employees earn at least the London Living Wage (£8.80) as a contract requirement.
Human resources director San Johal said: "Amenity horticulture has always been known as a low-paid industry and consequently suffered a lack of new people wanting to join as well as talented staff moving out. It is only through making a commitment to change this perception and improve pay and benefits that we will turn this around."