foliar feeding - i could talk about this for hours, yes i do recommend it if it is done right or to fix mineral deficiencies. plants thrive best on organic products that provide not only the NPK but also a range of trace elements. i believe its best to make a compost tea and spray with that, organic growing is amazing especially when you get into the realm of the microbes.
planting in pots if possible is definitely better, as you can aerate the soil with perlite etc and make sure the plant has viable nutrients available. if you were to plant in a very clay area the roots could either get root-rot or have trouble finding moisture. making plots then planting in the soil you have prepared is a good technique.
not sure of what the pH of kauai soil is but i would definitely have it tested before committing to it, and having problems down the road
here is vic highs soil mixex:
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Super Soil Mix
Original recipe - as it was given to me 1 Bale sunshine mix #2 or promix
2 L Bone Meal - phosphorus source
1L Blood Meal - nitrogen source
1 1/3 cups Epsom salts - magnesium source
3-4 cups dolmite lime -calcium source & pH buffering
1 tsp fritted trace elements
1/2 - 1 bag chicken manure (steer, mushroom, etc) - nitrogen & trace elements
- Mix thoroughly, moisten, and let sit 1-2 weeks before use.
Revised recipe - after several failures due to bad manure sources, I now use the following recipe. Results have been excellent and the clones seem to take off right away instead of having a slow growing settling in period.
1 Bale sunshine mix #2 or promix (3.8 cu ft)
8 cups Bone Meal - phosphorus source
4 cups Blood Meal - nitrogen source
1 1/3 cups Epsom salts - magnesium source
3-4 cups dolmite lime -calcium source & pH buffering
1 tsp fritted trace elements
4 cups kelp meal.
9kg (25 lbs) bag pure worm castings
- Mix thoroughly, moisten, and let sit 1-2 weeks before use.
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PG thread with subcools super soil(popular in cali):
http://www.planetganja.com/highsociety/showthread.php?p=876520
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pH is important because at certain pH levels some nutrients are available or not available for intake, aka nute lockout
here is an image with an explanation of what nutrients are available at what pH
http://www.gardenscure.com/420/attachments/plant-food-nutrients/245953d1219422712-soil-ph-38072489f5a0012efc.gif
as that picture states, marijuanas proper pH range is 6.3-6.8
aloha!