Need advice on Nutrients, and question on Flushing?

Doing Outdoor:
So i have decides some nutes will help right about now. I have a friend that wants to guide me and give me all i need. He started me off with 6 clones about 1.5 feet tall and 6 bags of roots organic 707. I dont however want to depend on him or travel 1 hour to see him.

What do you suggest i use for my plants? Looking for the best nutrients at a good price.

Also i have done a little reading on flushing and why its needed. From what i understand salt builds up at the roots from feeding it nutes.

How would i flush my plants if i cant even pick them up because they are in 30 gallon bags?

Thanks

If your looking to add nutrients to the water I've had great luck with fox farms. when growing outdoors I feed every other watering with a half strength solution, and only flush with straight water for the last two weeks of flowering. I usually have good returns and my crop always has an amazing smell and taste with no trace of chemicals. for the bags they should be able to drain from the bottom or sides. So its pretty much like watering.