To investigate the effects of mixed substrates of cow dung-maize straw compost and vegetable garden soil on the growth and quality of potted garlic seedings, an experiment was conducted from August to November 2024 using compost (1∶1 volume ratio of cow dung and maize straw) and garden soil as materials, with pure vegetable garden soil as the control (CK). The compost and garden soil were mixed at volume ratios to form 6 treatments: T1–T6 at 1∶9, 2∶8, 3∶7, 4∶6, 5∶5 and 6∶4, respectively. The physicochemical properties of the substrates were measured, and samples were taken at 30, 60 and 90 days after sowing to determine growth indicators such as plant height and quality indicators such as soluble protein content in the leaves and pseudostems. The results showed that compared with CK, as the proportion of compost increased, the bulk density and pH of the substrate gradually decreased, while the total porosity, water-holding porosity and aeration porosity gradually increased. The height, pseudostem diameter and pseudostem length of garlic seedlings in each treatment were significantly increased, and the root activity and chlorophyll content showed an overall trend of first increasing and then decreasing. The contents of soluble protein, vitamin C and allicin were all relatively high. The growth and quality indicators of treated with T3 were superior. At 30, 60 and 90 days, the plant height, pseudostem diameter, pseudostem length, leaf weight, pseudostem weight, total plant weight, root vitality, and chlorophyll content increased by 8.5%-22.4%, 51.0%-100.0%, 25.5%-58.4%, 13.0%-38.8%, 16.0% -29.0%, 15.6%-28.1%, 18.5%-36.4%, and 20.1%-31.2% respectively compared to the CK. The contents of soluble protein, vitamin C, and allicin in the leaves increased by 8.4% - 27.2%, 14.9% - 22.7%, and 37.0%-57.1% respectively compared to the the CK. The contents of soluble protein, vitamin C, and allicin in the pseudostem increased by 18.4%-24.0%, 15.7%-30.4%, and 18.9%-30.9% respectively compared to the CK. In conclusion, the mixed substrate of cow dung-maize straw compost and garden soil promotes the growth of garlic sprouts and the accumulation of photosynthetic products, improving their overall quality. The T3 treatment (3∶7 volume ratio of cow dung-maize straw compost to vegetable garden soil) demonstrated the best results and can be applied in garlic seedlings cultivation.