Again it's about beam angle so you wouldn't lower it to get the sides as much as point it where you want it. Big panels aren't as good as the smaller stuff with tight beam angles, (less than 90 degrees), for directional use but you can tilt them slightly to cover you plant better if needed. Or you can buy a bigger more powerful panel then raise it till it covers the whole plant
. Easy peasy but $$$. Or you could buy something like an Illumitex spotlight that has 50 or 10 degrees of beam angles and point it where you think it will help. Or Cree bulbs which would really help out here IMHO. Intensity is very important in LEDs and the budget stuff usually doesn't have very good intensity or efficacy (efficiency), though Advanced isn't as bad as most that's for sure.
Does that help?