The cultivation of catch crops left on the surface of the field in the form of mulch promotes sustainable farming practices, while protecting the biodiversity of agricultural landscape. The paper presents results of research from 2013–2016, aimed at determining the usefulness of catch crops of millet, buckwheat, white mustard, bird’s-foot and Egyptian clover for soil mulching in winter garlic cultivation. The effect of soil litter on the amount of garlic crop in cultivation for bunch harvest and nutritional value determined by chemical composition of edible parts was determined. In the edible part of garlic, the content of dry matter, total and reducing sugars, L-ascorbic acid, total ash, crude fiber, phenolic acids and essential oil was evaluated. The control consisted of plots without mulch plants. In the cultivation of garlic under organic mulch, there was no decrease in commercial yield and no negative competitive effect on yielding. Garlic plants cultivated with mulch plants were characterized by increased height and developed more leaves. The catch crops used in the form of mulch did not affect the dry matter and total ash content in garlic bulbs. In the cultivation with plant litter, the concentration of phenolic acids and essential oil in the leaves was higher and the content of crude fiber was lower, compared to the cultivation without litter. Biomass from catch crops from clover and mustard increased the content of L-ascorbic acid, at the same time reducing the content of total and reducing sugars in the edible part of garlic, except for mulch plants of the bean family. The chemical composition of garlic was affected by different thermal and precipitation conditions in the years of research. In 2016, the year with the highest total rainfall, plants accumulated more dry matter, L-ascorbic acid as well as total and reducing sugars than in 2014 and 2015, years with less rainfall. Our research indicates that there are prospects for practical application of catch crops in the form of mulch for garlic cultivation to enhance the level of nutrients, without compromising the yield.