The claims on fertilizer are just there to help sell the product. Most any decent fertilizer will have all the macro- and micro-nutrients necessary for plant growth. Some plants flower better if given a higher ratio of phosphorous relative to nitrogen, as too much nitrogen favors vegetative growth.

If you water and fertilize regularly the main limiting factors will be available light and availability of carbon dioxide. Good air flow will improve the latter. For many plants a porous soil mix will encourage good root growth but may require more frequent watering.

Plant growth regulators like florigen, auxins, cytokinins, gibberellins, and absisic acid can be used to alter growth in specific ways. These are usually applied at a particular stage of growth to achieve the desired effect.

FWIW I just use regular old miracle grow.

meyermike_1micha, and I wish to add that the life cycle of the plant plays an important role. All organisms exhibit an "S-curve" (Sigmoid curve) of growth. In plants you want do not want any limiting factors during the period of 'grand growth'- that steep portion of the "S" when the plant puts on most growth per interval of time.

Lycopus, it's phosphorus, not potassium? Oh, crap...

Supposedly it is phosphorous, although I was hesitant to add that part because there is probably more made of it than is actually the case. Lack of flowers could be attributed to low P availability, but a balanced fertilizer like 20-20-20 will probably yield the same number of blooms as 15-30-15. It is only likely to be a problem when a high N fertilizer that lacks the other nutrients is used.

Is there a steroid or other fertilizers better than another that will make a plant grow much more rapidily than its normal growth, or are these a bunch of false claims..

There is a steroidal plant hormone, brassinolide, but, in my experiments with a synthetic analog, epibrassinolide, plant growth was slightly inhibited.

There are some growth regulators that make apples and pears bigger.

There are some amazing experimental results for 1-triacontanol published in scientific journals but those results are difficult, if not impossible, to reproduce. Triacontanol is reputed to be widely used in Chinese and Indian agriculture.

Very interesting!

Thanks for making my visits to the hydroponics store alot less confusing and simpler for me, knowing I can just walk right past all these hundreds of different kinds and make a beeline for the FP.
This does have all the nutrients needed plus more.It even has calcium and Mg in it.
I can't handle walking into a supermarket wondering which tootpaste out of hundreds works best for my teeth, let alone the fertilizer that works best for my plants.lol

It is nice to come here and see such knowledgable people like you all so willing to share your expertise and kindness.

Lycopus, I am rather suprised though that you use just plain ole MG. I have been led to believe it is missing all the macro and micro-nutrients needed for most plants.. I have never had any luck using this..Hum
That is why I have been using FP which as ALL the minors,macro-nutrients and the 3 numbers..

Thankyou so much!

Let's see...I just went and got my package of Miracle Gro All Purpose Plant Food.

It is 15-30-15, so there are the primary macros; nitrogen, phosphorous, and potassium.

For secondary macros it does not list Calcium, Magnesium, or Sulfur. However, many of the salts listed are sulfates. The lack of Calcium and Magnesium are not of concern since I have hard water.

Micronutrients: Boron, Copper, Iron, Manganese, Zinc, and Molybdenum. Chlorides not specifically listed but provided by the various salts of the above.

Perhaps if you have soft water that would explain your lack of success using MG. A lack of Mg can be helped by the addition of vermiculite in the potting mix.

Thankyou Lycopus..:-)