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The primary focus was the determination of the yield and chemical composition of essential oils of honey balm (Monarda didyma L.) leaves and flowers as affected by using modern water-retention systems in the form of synthetic mulches: polypropylene non-woven textile compared with fabric and additionally supplemented with the geocomposite. The leaves were harvested for six months during subsequent plant development stages, through juvenile and generative to cessation of growth. Used in experiments, synthetic mulches contributed to reduced growth, fresh weight and flowering of Monarda ‘Scorpio’ plants. But these were not affected by the application of geocomposite. Twenty-nine constituents found in the green tissue samples of Monarda ‘Scorpio’ turn out to be mainly terpenoids with linalool (pure (R)-(-) isomer), p-cymene, thymol and thymol methyl ether as main compounds. The different chemical composition was represented by the flowers essential oil which possesses p-cymene and terpinolene (above 80%) as main compounds. Monarda ‘Scorpio’ oil revealed the strong antimicrobial activity and completely inhibited the growth of Candida albicans yeast as well as Bacillus cereus and Pseudomonas fluorescens bacteria in a concentration of 0.01%. In the other tested bacterial strains (Bacillus subtilis, Staphylococcus aureus, and Escherichia coli), elongation of the lag phase was determined or effectiveness at only higher (0.1%) concentrations of essential oil. Proven in our experiments, antimicrobial activity of Monarda 'Scorpio' EO was higher than that described in European Pharmacopoeia for used in herbal medicine sage, and comparable to the effectiveness of oregano.

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.

Auxins are the only compounds used in commercial plant propagation to stimulate rooting, although efforts have been made to find other efficient compounds. Another group of rooting promoters could be plant growth retardants (PGRs) which act as inhibitors of gibberellin synthesis. The aim of the experiment was to determine the effect of flurprimidol and naphthalene-1-acetic acid (NAA) applied by quick-dip method on rooting and development of Fuchsia hybrida 'Swingtime' cuttings and their subsequent growth. Anatomical analysis of the rooting process was also done. Flurprimidol and NAA did not influence the percentage of rooted fuchsia cuttings but increased the number of adventitious roots. Both compounds were involved in earlier formation of root primordia. Flurprimidol and NAA, used simultaneously or separately, increased the number and length of axillary shoots of fuchsia cuttings. The effect of flurprimidol on the number of roots and shoots was stronger than that of NAA, but diminished after transplanting the rooted cuttings. The influence of flurprimidol on axillary shoot length was weaker as its concentration increased.

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.

Portulaca umbraticola Kunth stem cuttings were treated with BA or BA and NAA in different concentrations. BA was applied by spraying or by the quick-dip method. Independent of application type, in almost all of the treatments BA and BA applied with NAA increased the percentage of rooted cuttings, but had no effect on the number of roots, apart from BA in the 0.5 g dm-3 concentration, which doubled the root number. Treatment with BA alone resulted in more intensive axillary shoot development, although only in one concentration (0.2 g dm-3) did BA significantly influence the number and length of lateral shoots. BA applied together with NAA had no effect or inhibited lateral shoot development. After measurement, rooted cuttings were planted in pots in order to assess subsequent plant growth. Our data indicated that the positive effect of BA on shoot development disappeared during the subsequent cultivation of the plants. BA alone applied by spraying did not influence the number and length of initial and secondary lateral shoots, whereas BA applied with NAA negatively influenced the length of initial lateral shoots as well as the number and length of secondary lateral shoots.