Bloom Boosters and Cannabis Flowering: Are they Necessary? 

For the most part, nutrient companies create and market their products for novice growers. These products are created for ease of use in small-scale, home cannabis gardens. While these branded, “all-inclusive” fertilizer lines are doubtless invaluable for hobbyist growers, the more advanced agronomist is questioning the necessity of such expansive feeding schedules. As such, there is a movement of growers looking to get “back to the basics” with their cannabis flowering practices.

One of the most formidable trends in the modern gardening marketplace is that of the “bloom booster.” Sold under catchy names and colorful packagingcannabis flowering, nutrient companies market bloom boosters as essential fertilizers to be used during cannabis flowering. Moreover, fertilizer companies also include bloom boosters a necessity in their feeding calendars. The kicker is, bloom booster products retail for as much as $250 for 500g. This pricing adds an additional expense on an already expensive practice.

To help the readers get an expert opinion on nutrient usage and bloom boosters, we reached out to accomplished cannabis grower and fertilizer developer Aaron Hoare. Hoare is the founder of Ambrosia Cropz, a three-part powdered nutrient line founded on “bare bones” ideals of simplicity and cost effectiveness. Hoare, like most expert gardeners, emphasizes critical analyses in cannabis cultivaiton. He pays particular attention to plant physiology and fertilizer programs founded on basic plant needs. This notion applies during both vegetative growth and cannabis flowering.

To gain a better understanding of fertilization methodology in relations to cannabis flowering and bloom boosters, Hoare has provided a basic overview of the practices he uses in the development of his own nutrient mixes at Ambrosia Cropz. These procedures are mainly structured around both irrigation and runoff water analytics. This brief study provides some insight into the bloom booster discussion through the eyes of a professional horticulturist and fertilizer developer:

N-P-K Ratios, Water Analysis, and Parts Per Million

While the fertilizer schedules included with most modern nutrient lines are quite valuable for the novice grower, these same gardeners will likely have to learn the basic elemental analyses of fertilizers if they hope to achieve extraordinary harvests. This brings us to the N-P-K ratio featured on all fertilizer products: (N) nitrogen, (P) phosphorous, and (K) potassium.

cannabis flowering

The three aforementioned elements are known as “macronutrients” and they serve as the essential foods for all plant life. Moreover, different levels of these macronutrients are required for stimulating growth during different phases of a plant’s life. During the cannabis flowering, many horticulturists agree that vigorous flower growth requires higher levels of phosphorous and potassium combined with lower levels of nitrogen. That being said, bloom boosters generally present an N-P-K ratio somewhere in the neighborhood of 0-50-30 or 0-39-25.

According to Hoare, those cultivators looking to critically explore their fertilizer regiments, including the use of bloom boosters, should begin by testing their irrigation and runoff water with a laboratory. These lab readings will show the parts per million of each macronutrient in their water after nutrients are mixed. The test with also show the salt build up in soil. As such, the resultant numbers provide a logical point of departure in deciding whether or not to use bloom boosters. The results can also be used make any other necessary tweaks to a fertilzier feeding schedule.

In the development of nutrient formulas at Ambrosia Cropz, Hoare applies this analytical, data-driven approach for fertilizer development. From these studies, Hoare came to the conclusion that with cannabis flowering, the ideal “ready for plant” irrigation water analysis in parts per million should be as follows: nitrogen 125 ppm, phosphorous 60 ppm, and potassium 165 ppm. It should be noted, again, that Hoare’s figures are formulated via a holistic approach to fertilizer scheduling that takes into account variables like nutrient build up in soil.

Most gardeners (novices and experts included), don’t have the time to consistently test their irrigation and runoff water with a laboratory to get ppm readings. However, these tests are one of the only ways for one to understand exactly what their plants are being fed. That being said, testing both irrigation and runoff water two to three times during a plant’s life will provide enough information to restructure a fertilization program founded on the basics.

For Hoare, it is a better bet to base nutrient formulations on the ppm readings of macronutrients in irrigation and runoff water rather than what is recommended on a nutrient feeding schedule. With this critical approach, Hoare recommends a N-P-K ratio of 7-6-12 during the flowering period. Obviously, these numbers stand in stark contradiction to the 0-50-30 ratios which abound in bloom booster formulations for cannabis flowering.

cannabis flowering

What does this Mean for Cannabis Flowering?

Plants can only handle a limited amount of fertilization—of any macronutrient—before the process becomes counterproductive. This notion is where Hoare’s ppm data really comes into play concerning bloom boosters. Because, according to Hoare, an overabundance of any macronutrient in irrigation water or a growth medium will actual hinder the uptake of all macronutrients. That being said, as far as bloom boosters are concerned, a majority of standard nutrient feeding regiments already contain sufficient phosphorous and potassium to stimulate cannabis flowering. Moreover, most expert growers agree that too much P and K can be toxic for plants and can actually retard flower growth.

With all things considered, if one wants to follow the more simplistic feeding approaches of Hoare and his contemporaries, they shouldn’t apply bloom boosters if their flowering nutrients already contain 40 – 60 ppm of phosphorous and 150 – 170 ppm of potassium when mixed with water. To reiterate, these numbers are based on a holistic approach to fertilization—taking into account factors like nutrient buildup from months of feeding. Most bloom booster formulations are created “in a vacuum,” so to speak, which don’t consider fertilization processes from planting to harvest.

Ironically enough, evolutions in modern gardening are often times stimulated by contradictions in thought and practice—like those seen in the delineations in theory presented by nutrient lines and “bare bones” horticulturists like Hoare. Concerning bloom boosters for cannabis flowring this difference in methodology could simply boil down to the experience levels of growers. For the novice gardener who doesn’t have the time, or interest, to test fertilizer formulations for maximum output, brand nutrient feeding schedules are an extremely practical choice. There is no doubt that they have given beginners the ability to produce crops unthinkable 20 years ago. That being said, if bloom boosters help these beginners achieve relatively good harvests, they should use them. However, for those more advanced, scientifically minded horticulture experts out there—the writing is on the wall. Not only are bloom boosters expensive, they are not always necessary.


This article originally appeared in the May 2018 edition of Maximum Yield Magazine.