As scatking said, watch out for the strength. What is on their site and bottles is much too strong for some (most) strains.
I start a 1/8th strength mix for little seedlings. They love it.
Then I move it up as they grow, by 1/8th's in strength. I watch the leaf tips and edges of the NEW GROWTH and OLD GROWTH to see if any signs of overage is noted. If so, I back down to the last known good strength.
Here's two examples:
1. Big Bud, even during full vegging at 4 feet tall, half strength GH burned it.
2. Bubba Kush, even when only 5 inch rooted clones, just started good, took and used FULL STRENGTH GH nutes and ate it like it was candy.
So you can see that there really ISN'T a "rule" to go by, other than using small and working your way up.
I would strongly recommend using the same ratios as they have on the bottle and site.
Mixing 1/8th strength is easy and requires very little measuring.
Use a single one gallon container to mix the primary batch. Use a MEASURING SPOON, not an eating spoon and measure exactly:
1. 2 teaspoons (10ml) of the MICRO (Brown) nute into the two gallons of water. It's VERY IMPORTANT to put the MICRO into the water first. If you don't, it'll cause SEVERE LOCKOUT of the nutes.
2. Then, after mixing the Micro into the water, add 3 teaspoons (15ml) of the GROW (Greeen) nute into the water with the micro in it.
3. Then, add 1 teaspoon (5ml) of the Bloom (Orange) nute to the same container.
Mix well and you now have FULL STRENGTH GH nutes for vegging.
To take it to 1/8th strength, simply pour 16 ounces of this mix into another gallon container and add water to fill.
To make 1/4 strength, pour 32 ounces of the full strength into another gallon container and add water to fill.
To make 1/2 strength, pour half of the primary gallon of full strength into a new container and fill.
There's everything you need to know about the vegging side.
When moving to flowering nutes, simply turn the numbers around on the GROW AND BLOOM nutes. It would be 15ml of BLOOM and 5ml of GROW.
The micro nutes are ALWAYS added to plain water first! This is ABSOLUTELY necessary.
The micro nutes are always the same strength in the primary.
The ratios HAVE TO STAY:
Vegging: Grow 3, Micro 2 and Bloom 1
Flowering: Grow 1, Micro 2 and Bloom 3
GH nutes are formulated to use in these ratios for marijuana. I keep seeing growers talking about using them in a 1-1-1 ratio and that is totally, irrevocably, unmistakably wrong.
As with anything, if you start playing like *you're* the scientist, and ignore what *their* real scientists have already figured out, you take the health of your crop into your own hands.
Good luck man!
Go slow, start small, work your way up and WATCH your plants new growth and old growth for changes.