Silicon is an element that significantly reduces the vulnerability of plants to biotic and abiotic stress factors, increases their resistance to pathogens and pests, strengthens tissues and cellular membranes, increases biomass and crops, improves the nutrition state of plants and increases the chlorophyll content. It also influences the formation of morphological traits of plants. The aim of our research was to determine the influence of silicon contained in the Actisil preparation on the growth and blooming of Gazania rigens, Salvia farinacea and Verbena hybrida, which are commonly cultivated in flowerbeds and on balconies. A two-factor experiment consisted of the foliar application of a solution of silicon in the following concentrations: 0 mg dm -3 , 120 mg dm -3 and 240 mg dm -3 . The application was performed 2, 4 and 6 times at one-week intervals. Biometric measurements were carried out at the beginning of the blooming of plants. The laboratory analyses included determinations of P, K, Mg, Ca, Si and the chlorophyll content in leaves. Beneficial influence of silicon on most of the morphological traits of the analysed species was demonstrated. Plants responded the best to two or four treatments with the silicon solution of a concentration of 120 mg dm -3 , with an increase in the values of the analysed morphological traits. The application of silicon did not significantly modify the content of mineral elements in the dry weight of leaves. The application of silicon to Gazania rigens led to an increase in the content of this element in leaves as well as to an elevated chlorophyll content.

Silicon supplementation may lead to positive changes in plant quality, including their appearance. The two-factorial experiment with three ornamental plant taxa Gazania rigens 'Kiss Yellow', Salvia farinacea 'Fairy Queen' and Verbena 'Obsession Lilac' was conducted in the years 2012-2013. The first factor was foliar application of Si in form of ortho-silicic acid stabilized with choline (YaraVita Actisil) at the concentrations of 60, 120 and 180 mg·dm -3 , while the second was soil application of multinutrient fertilizer (Insol U) at the concentrations of 0.25% and 0.50%. Biometric measurements of plants were carried out at the beginning of flowering. The laboratory analyses included the determination of the content of P, K, Ca, Mg and Si as well as chlorophyll content in the leaves. Silicon had a beneficial influence on a majority of the analysed morphological features. Plants reacted best to high silicon doses (120 and 180 mg·dm -3 ). Particularly beneficial effects were noted with respect to improved flowering of all analysed plant taxa and to the vegetative development of Salvia and Gazania. Insol U supplementation noticeably improved the flowering of Verbena.