Pardon me if I seem confused, but are you asking if you can ingest any brand of kelp, or use any brand in your garden?

There are different kinds of kelp, and they are not all the same.
I may be wrong, but all of them are not classified as food grade. Some have higher levels of arsenic than others.

I would think that if the kelp is food grade you could use it in your garden.

Yes it is foodgrade bought from health food store , but how much do I add to the water ? What is the ratio for mixing with water to make a drench for a shrub ?
Thanks
Laura

Any kind of seaweed or kelp used as a foliar feed or soil amendment drench, will act as a great micronutrient fertilizer and a powerful biostimulant beneficial microbial food source.

I buy cheap $2.00 packs of dry seaweed or kelp from local oriental grocery stores, and soak in 5 gallon buckets of rainwater, with a little molasses, for extra microbial action and faster decomposition.

I think the recommended ratio is usually about one teaspoon to a gallon of water?
-O

I just bought some 100% soluble seaweed powder and the instructions are:
Potted plants: 1 tsp/gal water for root feeding every 3 weeks. Use 1/2 tsp/gal for foliar spray between root feedings.
Garden plants and flowers: As above, only double amount of seaweed/gal of water.
Lawn and fruit trees: As above, only triple the amount of seaweed/gal. Spray 3 or 4 times during the growing season.