Watering in 5 gal buckets

Hey everyone. This is my first grow and I have some watering questions. I have two plants about 6" tall in 5 gal buckets. They are under a 250w mh bulb.They have been growing for 6 weeks in ffof soil with no nutes added. My problem is that I want to add nutes but I don't want to overwater to do it. I'm trying to be patient but it's been 1 1/2 weeks since I last watered and the soil is still moist in the middle and wet at the bottom. Also there are plenty of drainage holes in the bucket. The bottom leaves on the plants are turning yellow also. Don't know if it's from lack of nutes or too much water. Any help would be great. Thanks

mix your plant food with some water and spray the plants down. do it when the lights are off though.

Thanks for the response. I gave sprayed them with seaweed extract but not with any full streangth nutes. I will give that a try with maybe diluted ff grow big? I bought the trio because I've heard good things about it.