A field experiment was conducted in the years 2017-2018 in the area of the Didactic and Experimental Centre, University of Warmia and Mazury in Olsztyn. The experiment was set up in the randomised split block design, in three replicates. The first experimental factor was four winter cultivars of garlic (Allium sativum L.): ‘Arkus’, ‘Harnaś’, ‘Mega’, ‘Ornak’. Within the scope of the second experimental factor, the effect of amino acid biostimulators Calleaf Aminovital and Maximus Amino Protect on the yield and quality of garlic was analysed. The control treatment comprised plots on which only water was applied. The objective of the study was to estimate selected morphological features of bulbs and the content of nutritional components of garlic cultivated with the use of biopreparations. The morphology and the nutritional composition of the edible part of garlic was estimated. Statistically significant impact of the cultivar on bulb mass and horizontal diameter and on the content of L-ascorbic acid and nitrates (V) in the edible part of garlic was demonstrated. Cultivar ‘Ornak’ was characterised by greater bulb mass (64.62 g), vertical and horizontal diameter (4.09 and 4.14 cm), dry matter content (38.0%) and concentration of reducing sugars (1.18 g 100 g^–1 fresh matter). Lower bulb mass, height, content of total and reducing sugars and of nitrates (V) were determined in garlic cv. ‘Arkus’. The cultivation of garlic plants with the use of the biostimulators had a significant effect on the number of cloves in a single bulb. The application of Calleaf Aminovital increased their number to an average of 6 cloves×plant^–1. Interaction of garlic plants cv. ‘Arkus’ with Calleaf Aminowital significantly reduced the content of nitrates (V) in garlic relative to the remaining cultivation treatments.