Borris uses 90 x 2 = <<90*2=180>>180 kilograms of grapes per year.
The increase of kilograms of grapes he needed per year is 180 x 0.20 = <<180*0.20=36>>36.
Therefore, Borris needs 180 + 36 = <<180+36=216>>216 kilograms of grapes in a year.
#### 216