Monitoring the Stem Growth of Transplanted Semi-Wild Stinging Nettle (Urtica dioica L.):small scale finnish field plot study – a preliminary step to a clonal propagation programme

Abstract

Stinging nettle (Urtica dioica L.) is a perennial herbaceous plant widely distributed from the Arctic to the Mediterranean, providing significant ecological value. It is economically important due to bioactive compounds in wild varieties, such as phenolics, carotenoids, and chlorophylls, which enhance resilience and industrial potential. Several European countries have developed superior wild varieties and improved clonal plants, whereas Finland has very few clones, mostly limited to northern trials like the ARKNOK project, with none in southern regions despite favourable conditions. Effective propagation is essential for industrial cultivation, but both seed-based and vegetative methods remain under research. Seed propagation, commonly used in Finland, is often unreliable, and wild harvesting exerts pressure on natural populations, highlighting the need for cost-effective and reliable methods. This study tested a novel cost-effective approach by transplanting semi-wild nettles into managed field sites in southern Finland and monitoring growth over nine weeks. Forty plants were planted in four 1 × 0.5 m plots, arranged 10 plants in two rows per plot. Stem number and stem length were recorded weekly, and soil and environmental conditions were assessed. Data analysis included box plots, average growth trend charts, ANOVA, Pearson’s correlation, and survival rate calculations. Results showed significant differences in stem number (p = 5.44 × 10⁻¹²) and stem length (p = 1.46 × 10⁻⁴⁷), with box plots and average charts indicating steady upward growth. Pearson’s correlation (r = 0.317) showed that plants with more stems tended to grow taller, but also with other varieties to select. Survival rate was 97.5%. Overall, semi-wild nettles displayed vigorous growth, uniform development, and strong adaptability. These plants show wide varietal differences for selection, require low inputs, and are cost-effective at the initial stage. Superior individuals can be selected and used for clonal development, supported by chemical and anatomical analyses, enabling future sustainable nettle cultivation in Finland, enhancing local industries, reducing pressure on wild populations, and contributing to the local economy.