Azo Root EarthMAX combo boosts poinsettia rooting

A recent study led by Virginia Tech researcher Xunzhong Zhang has found that combining Azo Root and EarthMAX Organic significantly improves poinsettia plant health, leaf color and root development.

The greenhouse trial tested the microbial biostimulant Azo Root, developed by Harrell’s and 3Bar Biologics, both independently and in combination with EarthMAX Organic. The products were applied to both callused and uncallused poinsettia cuttings in a greenhouse environment under shade and mild stress.

Treatments were administered as a soil drench at 2 gallons per 1,000 square feet, with weekly fertilization using 20-20-20 fertilizer plus micronutrients.

Azo Root™ paired with Harrell’s EarthMAX® Organic produce noticeable improvements to plant health, leaf color, photochemical efficiency, leaf chlorophyll, and root growth/biomass. Photos courtesy of Harrell’s.

Observations showed that plants treated with Azo Root and EarthMAX Organic displayed greater photochemical efficiency as early as 14 days after the first application. These improvements were consistently maintained through days 28, 42 and 56 compared to untreated controls.

The combined treatment outperformed Azo Root alone in several key areas including plant health, leaf color and root biomass, with “Red Premium” uncalloused cuttings demonstrating higher root surface area and volume than callused “Ice Crystal” cuttings.

“The combination opens doors to growth that were previously much more difficult to achieve,” said Xunzhong Zhang.

While chlorophyll content increased with treatments, the differences were not statistically significant. However, overall results confirmed that Azo Root paired with EarthMAX Organic had the most consistently beneficial effects across multiple plant health metrics.