The effect of silicon foliar application on the development of Season ornamental plants. Part II: Argyranthemum frutescens 'Blazer Rose', Xerochrysum bracteatum 'Gold', Osteospermum ecklonis 'Grande Pink Blush' and Gaura lindheimeri 'Corinas Choice'

Recent research has proved that supplementary application of silicon, involved in plant tolerance against many stress factors, positively influences plant development improving the quality of ornamental plants. A two-factorial experiment involved four cultivars of ornamental plants: Argyranthemum frutescens 'Blazer Rose', Xerochrysum bracteatum 'Gold', Osteospermum ecklonis 'Grande Pink Blush', and Gaura lindheimeri 'Corinas Choice' The first experimental factor was the concentration of Actisil preparation being an equivalent of 60, 120, and 180 mg Si×dm-3, applied three times by spraying, while the second one was the type of medium: peat substrate and peat substrate with sand. Actisil had a beneficial effect on the number of lateral shoots in all plants. The highest number of buds and inflorescences was determined in Xerochrysum and Osteospermum plants sprayed with 0.3% Actisil, and 0.2% Actisil in case of Argyranthemum and Gaura. The effect of medium type on plant growth depended on plant species. Argyranthemum and Osteospermum plants cultivated in the medium with sand showed inhibited growth, although medium type did not affect the growth of Xerochrysum