Euphorbia ×lomi produced considerable amount of flower racemes after exposure to Mediterranean winter temperatures

Poysean (Euphorbia ×lomi Rauh, a spurge natural hybrid of E. milii Des Moulins × E. lophogona Lamarck) is widely grown in south-eastern Asian countries, where winter minimum temperatures are above 20°C. Poysean was recently proposed for indoor uses in Mediterranean countries thanks to its great size inflorescences and long-lasting flowering. In addition, this spurge has a very high ability to withstand long water shortage, high summer temperature and can be easily propagated by cutting. However, little is known about its ability to withstand the minimum winter temperatures of the Mediterranean areas. An outdoor experiment was performed to evaluate poysean tolerance to the winter temperatures of the thermo-Mediterranean climate and its potential use as ornamental crop for outdoor stands and window box. Two genotypes of E. ×lomi ('Nguen Muang', NM; and 'Soi Budsarin', SB) were grown at 2 or 3 plants pot-1 in window boxes during 26 months. Number of flower racemes (cyathia) and leaves plant-1, plant height, and pot ornamental value were measured monthly. No differences were observed in scores from the panel members. On average, NM showed 36% lower number of flower racemes, but 30% higher panel score than SB. During winter, NM showed a higher number of flower racemes plant-1 than SB. Few effects of plant density on flower racemes and panel test score were found and these were mostly in magnitude. The present data suggest that Euphorbia ×lomi is still able to survive and produce flower racemes during winter in the thermo Mediterranean climate and it is suitable as an ornamental plant for open-air stands and window box and likely for xeriscaping and green roofs.