Using Biostimulants to Improve Growth in Tagetes

By Greenhouse Grower staff|May 14, 2026

Representative French marigold (Tagetes patula ‘Durango Yellow’) plants provided with 2.5, 5, 10, or 20 mg·L−1 P and treated at transplanting with Lalrise Vita containing Bacillus velezensis or untreated. Photos were taken four weeks after transplanting. Photo: HortTechnology

Biostimulants are increasingly being used by the floriculture industry to improve nutrient use efficiency and crop performance. A recent study by a team of researchers at The Ohio State University evaluated the effects of Lalrise Vita, a commercial biostimulant from Lallemand Plant Care containing the phosphate solubilizing bacteria, Bacillus velezensis, in combination with different phosphorus (P) levels on the growth of French marigold (Tagetes patula ‘Durango Yellow’). The plants received 2.5, 5, 10, or 20 mg·L−1 of KH₂PO₄ and were either untreated or treated with 0.25 mg Lalrise Vita per plant.

Greenhouse-grown plants were then evaluated for digital biomass, canopy color distribution, normalized pigment chlorophyll index (NPCI), and tissue nutrient concentrations. Lalrise Vita–treated plants provided with 2.5 and 5 mg·L−1 P exhibited significantly higher biomass compared with untreated plants at the same P levels, achieving growth comparable to untreated plants at 20 mg·L−1 P. Lalrise Vita application also enhanced foliar P concentrations and contributed to greener canopy hues, although increased plant growth also led to reduced leaf nitrogen (N) concentration and elevated NPCI values, suggesting greater N demand.

The results demonstrate the potential of Lalrise Vita to enhance nutrient acquisition under different P concentrations. The combination of the Lalrise Vita with 5 mg·L−1 P promoted plant growth that was comparable to untreated plants at 20 mg·L−1 P, highlighting its role in reducing P inputs. The accelerated growth with Lalrise Vita may also increase the demand for other nutrients.

You can find a more detailed look at the research study and its results in this post from American Society for Horticultural Science.