A quick change rotary mower blade assembly 100 comprises a spindle 106 with an internal bore and compression spring 110 positioned in said bore, a blade retainer 114 secured below the spindle having a pair of arms 132, 134 and a mower blade 102 assembled to a blade assembly pin 104 which is inserted into the internal bore to compress the spring. The spring exerts a force so that the blade is secured against the blade retainer arms below it. Also disclosed is a mower blade assembly with a spindle with an internal bore, a blade adapter, a mower blade with a centre hole and a blade assembly pin. The blade assembly pin being releasably engaged to the spindle from a handle on the mower deck. Also disclosed is a mower blade assembly where rotating the mower blade 90 degrees secures it in place on a blade retainer.
