One thing to always remember when deciding on what nutrients to go through, there are a few factors you probably should consider first.
Are you a soil grower?
>>Have you ever wanted to make a compost pile?
Do you grow from a hydroponic system?
>>What nutrients and how should you design the tea? (tea meaning nutrient formula)
Do you want to be a hippy and use organic nutrients?
There are many things the novice may not notice or consider when looking around for products to maximize their plants growing potential. If you a soil grower, it comes down to deciding how you plan to grow whether inside or in the great outdoors. If the decision comes down, lets say outdoors in the woods in your secret grow spaces, it's best to mend your soil the fall before. There are a lot of great things that take time to break down to provide essential nutrients.
Take mexican bat guano for instance, it is rated to have 10% nitrogen, but you notice the package says 9% Insoluble nitrogen, while 1% is water soluble. This means that only 1% of the nitrogen is readily available in water. It has to be broken down by microbial forces in the soil for it to become available to the plant. So it does not make sense to purchase bat guano as a fertilizer in your hydroponic tea, does it?
Composting is the greatest and most beneficial thing you can do for a Marijuana plant you intend to grow outdoors. Tilling your soil with compost provides necessary bacteria and microbial forces as well as readily available nutrients for the plant to absorb and create a healthy root system. Highly recommend for outdoor growing, Indoor soil growing there are easier alternatives and less time consuming to create the compost.
The smoothest, and most enjoyed smoke has been known to come from soil.
Soil"less" mixtures are great as they are made to accept the specially formulated teas that people relish in they're own rights. I prefer to keep a good organic potting soil with natural amendments. Organics tend to cause sweeter buds in my opinion, nature knows best you know! Organic nutrients are said to have a gentler, happier and much more readily available nutrients for the plant to absorb. Fox Farm Big Bloom I think is the best foliar spray mix you can purchase. It has "just the right" amount to give the plant a small boost.
Hydroponics is always important to stick with the liquid fertilizers, or the kind that you can put into a coffee filter & float in the reservoir. If it is not water soluble, you are wasting your time and money. You also don't want to be a stoner and put items into the reservoir that may cause it to clog. Hydroponics is great as you can become "god" over the plant and provide to it exactly what it needs in strong and manageable doses causing massive fruiting and optimal growth.
Additives like Molasses (black strap) are encouraged towards flowering to promote bud weight. They are carbohydrates (sugars) and can augment bud weight by 40%-60% and pack on more trichomes. There are additives you can also purchase at your local hydroponics stores that would increase this, and the "secret ingredient" is often blackstrap molasses! (a little secret for you!)
Foliar feeding is also an option for nutrients especially if they seem a bit depressed, it can cause an insta-perk up within an hour. They now make many kinds specifically for this purpose, but just remember its probably diluted of the product sitting directly next to it, so measure carefully. It is very easy to burn plants with foliar spray. a pH of the water around 6 is a must for hydroponics. This way, none of the elements of plant life are restricted as 1 point is considered 1000 times stronger (ph 6 is 1000 times more acidic than ph 7, and so forth)
Once you begin to bud, i would recommend against foliar feeding, wouldn't want to promote mold growth on the buds. Botrytis (bud mold) kills and spreads quickly, somewhat almost seemingly overnight!
Below is a list of what is called "Macro Nutrients" or, the major ones.
Nitrogen, Phosphorus, Potassium. The "Big 3" if you will, known as N P K. (atomic table)
Nitrogen is important during the vegetative growth stage. It assists in massive production of green growth & chorophyll production. It is supported by Calcium & Zinc the most.
Phosphorus is important during the flowering stage, or blooming stage. The plant reverts to this to assist in its hormonal change to grow the fruits related to the plant, or in weeds case "buds".
Potassium is important for overall plant health. It is rumored that a high potassium diet for early marijuana plants (vegetative growth) causes more male plants.
The "Micro Nutrients" or the nutrients that are use for standard processes (usually relating to the absorption of other nutrients)
Iron, Zinc, Calcium, Chlorine, Boron, Molybdenum, Silicone, Magnesium, and some others.
The ones you usually worry most about are going to be Zinc, Calcium Iron and magnesium. These are the ones most often found deficient in hydroponic systems.
Too much iron screws up the intake of Zinc, So if the plant cant absorb or doesnt have Zinc to absorb the plant cannot process nitrogen, without nitrogen it cannot produce chlorophyll / photosyntehsis and soon yellowing of leaves begin.
So sometimes a deficiency in the micronutrients can mask as a deficiency in the macronutrients
Always remember to think about what you need most and always have a good micro-nutrient supplement supply readily available if you need to supplement. There are a lot of websites that help explain what deficiencies of all nutrients cause, so make sure to check it out for more detailed information.