LK is indeed a great product that will supplement your garden in both veg and bloom. Use it every time you feed your girls. It's not going to double your yields or anything like that but it will supply your plants with nutes to avoid deficiencies down the road and will keep healthy beneficial microbe activity in the root zone. It's basically a combo of sea kelp, humic acid, and yucca extract. Good stuff!
It's great for both hydro and soil and can be used on seedlings and cuttings too. Can also be used as a foliar spray but humic acid is better served in the root zone than on the leaves.