You would need at least 5 of those in order to hit 50 w/SqFt formula target.

4.5' x 1.5' = 6.75 Sq Ft of grow space
6.75 x 50 = 337.5 Watts of light
337.5 / 65 = 5.2 LOA fixtures needed

For the same money you could get better fluorescents. For example, www.100bulbs.com, has several large CFLs that have the ballast built-in for a comperable light, eg. 105W-$25.