There really is no "last minute magic". The best one can do is to continue to provide optimum conditions.
Flushing--
When you start seeing the bud hairs start to change color from clear/milky to red/brown, stop using nutes. You're about 2 weeks from harvest. Continue to water with plain water.
If you used potting soil that came with chem fertilizers in it, or if you added chem fert's, you'll need to flush, which means pouring 3 times the amt of volume of the planter of water through the soil.
Meaning, if you have a plant in a 5 gal. container, you'll need to use 15 gal's/water to get rid of the chem's, if you don't the weed will burn poorly and taste crappy.
If your growing organic, there's no need to flush. Just use plain water for the next 2 weeks.
