According to the agronomic requirements of garlic sowing, the garlic morphology is studied and a garlic seed metering mechanism with excellent seeding performance is designed. Based on this design, a new garlic seeding machine with an adjustable-size seeding device is developed to realize efficient single-seed metering and seeding of different varieties of garlic. Further, the design scheme of the garlic seeder prototype is established, with the key components of the garlic seeding being designed on the basis of the garlic seeding mechanism. To achieve garlic single-seed metering for different varieties of garlic, the optimal adjustment size of the garlic seed metering device is determined through discrete element simulation analysis. A field experiment confirms the effectiveness of applying the proposed garlic planter to field sowing in terms of the metrics of missing seed and multiple seed rates. The results of the discrete element simulation test reveal that an adjustment size of 40 mm yields the best single-seed metering performance. At an operating speed of 15–35 rpm, the metering device can achieve more than an 80% qualification rate of single-seed metering, with a unit speed of 0.628–1.465 m/s. Thus, the developed garlic seeding device meets the requirements of precision sowing in China and can effectively realize the mechanized planting of garlic.

Aiming at the problems of low single-seed rate, high rate of missing seeds, high rate of multiple seeds, and low rate of upright seeds in the mechanized sowing of garlic seeds, this paper proposes a structural design scheme of a type hole wheel garlic seed metering device based on the characteristics of garlic species. Based on the agronomic requirements of garlic planting and the characteristics of garlic species, the mechanism of the hole wheel structure to improve the seed filling performance of the seed metering device was clarified, a structural parameter design of the key components of the device was established through theoretical calculations, and a single-factor simulation test was conducted using the Engineering Discrete Element Modelling (EDEM) software. Using the Design-Expert 11 data analysis software, a mathematical regression model of each test factor and test index was established, and the test factors were analyzed. The parameters were optimized, and the following was found to be the optimum parameter combination: seeding wheel speed of 30 rpm, profile hole depth of 18 mm, and adjustment length of the profile hole of 41 mm. The EDEM simulation test results showed a single-seed rate of 91.67% and a missing seed rate of 4.17%. The bench test results showed a single-seed rate of 89.2%, a missing seed rate of 5.0%, and a multiple seed rate of 5.8%. The field test results showed a single-seed rate of 88.44%, a multiple seed rate of 4.11%, a missing seed rate of 7.44%, a breakage rate of 1.11%, and an upright rate of 62.36%. The errors between the bench test/field test and the discrete element simulation test results were 2.7% and 3.5%, respectively, which were consistent with the simulation results, thus meeting the requirements of single-seed sowing using the garlic seed metering device.