Flower color — Lobelia erinus

In Lobelia erinus variety trials, flower color is assessed visually using the Royal Horticultural Society Color Chart. Since this is a qualitative trait, the entire color spectrum is recorded, ranging from white and blue to pink and purple, including the presence of characteristic elements such as the eye at the base of the petals.

The expression of this trait is closely related to environmental conditions. Temperature stress above 24°C leads to the fading of blue flowers, while deviations in soil acidity from the optimum pH of 5.8–6.5 or nutrient deficiencies can cause petal paleness and pigmentation disorders.

Agrotechnical factors, particularly an excess of organic matter, promote vegetative growth at the expense of flowering quality. To maintain varietal purity and color intensity, strict adherence to the nutritional regime and the maintenance of plant physiological health are required.