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An evaluation of retail fertilizers for home use: a Guelph Turfgrass Institute research project

A healthy, lush green lawn is the goal for many homeowners, and achieving this often requires the use of fertilizers. In Canada, especially in regions with pesticide application bans, homeowners rely on fertilizer products to ensure dense turf growth that out-competes weeds and maintains the functionality of their home lawn. 

In a recent study at the Guelph Turfgrass Institute, we looked at a range of fertilizer products available in retail stores and evaluated cost, ease of application, and effects on turf quality. We hope to shed light on the commercial fertilizer products available, so homeowners and lawn care professionals can make more informed choices for their turf management practices.

In this study, we assessed the impact of 12 different fertilizer treatments on a non-irrigated, three-year-old stand of Kentucky bluegrass established from sod, with no herbicides or insecticides applied. To ensure reliable and accurate results, we used a randomized complete block design with three replications. The treatments represent a range of options available to homeowners and lawn care professionals. These treatments included various formulations, nutrient ratios, and application schedules.

Cost consideration
When it comes to purchasing fertilizers, cost is often a significant consideration. Some of the products used in this trial were donated by industry suppliers, and, since their retail price is not posted online, we have omitted the price from this article. The most expensive retail fertilizer products were GolfGreen Bone Meal and Acti-Sol Mother Hen Fertilizer, which admittedly are not designed to be applied in bulk, but they were included in this study since the package instructions included home lawns. The most inexpensive product per square metre was GolfGreen Nitrogrow with GolfGreen Fall Fertilizer. 

Ease of application
Granular fertilizers (treatments one, three, five, six, eight, nine, 10) were easily applied using a whirl hand-held spreader (retail price is $30.50).

Since the nutrient guarantee on GolfGreen Bone Meal, Acti-Sol Mother Hen Fertilizer, and MinRock Ultimate Compost is so low, the rate of application (~1000 g / 10 m2 plot) was nearly 10 times higher than other products. Ensuring this amount of product was evenly distributed and incorporated into the turf canopy was notably more difficult. This was also true for Bella BioChar (2241 g /10 m2 plot), which is designed to be incorporated into the soil before turf establishment, and, unfortunately, that was not an option for this trial. The Bella BioChar treatment was messy to apply, resulting in clouds of black dust which required the use of mask and goggles, but the BioChar treatment only needs to be applied once in the lifetime of the turf.

The EarthAlive Soil Activator treatment was the only product applied as a liquid. The fine powder gave us some difficulty when mixing, since it would form hydrophobic clumps if mixed too quickly. This treatment was applied using a three-gallon hand-pump sprayer (retail price is $36.15), and unfortunately the sprayer needed to be refilled for each 10 m2 plot which would be inconvenient when treating larger areas. The choice between solid and liquid fertilizers ultimately comes down to the applicator’s comfort level. Solid fertilizers are user-friendly and require minimal effort, while liquid fertilizers may be better suited for those willing to invest more time and effort to ensure proper calibration of their equipment.

Turf quality
Each of the treatments were applied according to the label instructions between April 25, 2023 and Sept. 13, 2023. A digital image was taken using a drone at 17 metres altitude weekly from April 25, 2023 to Oct. 27, 2023. These images are available on our social media platforms (@GuelphTurf on Twitter, Instagram, and Facebook). The plots were two metres by five metres, and each image was digitally analyzed for average red/green/blue colour content using devpicker.com/image-average-color. The colour values were standardized for blue content and the green:red ratio was used as an estimate of turf quality (higher value equals brighter emerald-green colour). 

The average greenness value was calculated from the three replications across the study, and the performance of the products was then ranked from high (#1) to low (#12). When averaged across the entire season, the treatment rankings from highest to lowest are as follows: Vigoro Lawn Fertilizer, Mother Hen Fertilizer, Mother Hen + Bella Biochar, Ultimate Compost, Nutryon HiViz /GreenTRX/C2Charge, Bone Meal, TurfBuilder Pro, Bone Meal + Biochar, Turf Builder Summerguard, GolfGreen NitroGrow & Fall Fertilizer, 10-0-0 with PBS150, EarthAlive Soil Activator. 

Several treatments were impacted by their application schedule. For example, the turf quality of Treatment 1 (Scotts Turf Builder Summerguard) peaked two weeks after the second application. The quality of GolfGreen Nitrogrow was at the highest at the beginning of the season, and then fell in rankings over time. EarthAlive Soil Activator, which contains soil microbes, was consistently ranked low likely due to the lack of macro-nutrient content. This product may be more effective in combination with irrigation and/or additional fertilization.

Iron content
Iron content in fertilizers plays a pivotal role in enhancing turfgrass quality. Iron is an essential micronutrient that helps to maintain the vibrant green colour of the grass. It aids in chlorophyll production, which is crucial for photosynthesis and overall plant health. By ensuring the grass receives an adequate supply of iron, it not only regains its lush green appearance but also becomes more resilient to environmental stresses. Thus, the iron content in fertilizers is a key factor in promoting the optimal aesthetic and health of turfgrass. It cannot be overlooked that some of the top-performing products contained iron. Acti-Sol Mother Hen, MinRock Ultimate Compost, and Nutrite Nutryon HiViz /GreenTRX/C2Charge were ranked within the top five treatments throughout the season and have some iron content (0.1% Fe, 0.8% Fe and 0.9% Fe, respectively). Iron content wasn’t a consistent predictor of turf quality, but it is something to consider when purchasing fertilizer products. 

Cost/performance considerations
Of the products purchased from retail stores, Vigoro Lawn Fertilizer gave the biggest “bang for its buck.” Mother Hen Fertilizer resulted in a surprisingly nice dark green colour which was maintained throughout the season, but the fact that it needed to be applied four times, plus the cost, and the effort needed to hand-spread the product (it doesn’t fit properly in a whirl hand-spreader), means that Mother Hen Fertilizer might not be worth effort and cost for turfgrass use. MinRock Ultimate Compost and the Nutrite product are next in line but are exempt from the cost/performance analysis since they were donated products. GolfGreen Bone Meal alone was in the top six for turf quality, but the price is 15 times higher than that of traditional synthetic granular fertilizers. 

This project was made possible thanks to our industry donors and Landscape Ontario. Visit www.Lawn.Science. 

Dr. Sara Stricker is the communications and outreach co-ordinator at the Guelph Turfgrass Institute.