Fertilization patterns of garlic

Garlic is one of the vegetable crops that require substantial fertilizer and exhibit relatively high tolerance to fertilization. The dynamics of nutrient uptake at different growth stages follow an increasing trend as plant biomass accumulates, with the final 80 days representing the period of greatest nutrient demand.

Germination period

From sowing to the emergence of the first true leaves, garlic is in the germination stage. During this period, root growth is primarily vertical, the growing point successively differentiates new leaves, and the roots’ main function is to absorb water.

Due to its small growth and short growing period, it consumes relatively few nutrients, which are supplied by the seed garlic itself.

Seedling stage

From the emergence of the first leaves to the initiation of scale bud and flower bud differentiation, this is the seedling stage, during which new leaves continuously differentiate, laying the groundwork for the development of scale buds and flower buds.

From germination through seedling growth, the developing seed garlic supplies the nutrients. As the seedlings grow, the stored reserves in the seed garlic are gradually depleted; once these reserves are exhausted, the parent bulb begins to shrivel and dry out—a stage known in production as “mother‑bulb regression.” This regression typically occurs around the end of the seedling phase. During this period, garlic growth relies entirely on soil‑borne nutrients, and its nutrient uptake increases markedly. If soil fertility is inadequate, the plants may suffer from a nutritional imbalance, resulting in dry, scorched leaf tips.

Scale bud and flower bud differentiation stage

After the seedling stage, garlic enters the period of bulb‑bud and flower‑bud differentiation. During this phase, new leaf formation ceases, with growth shifting primarily to the leaves; the shoot apex develops floral primordia, while bulb buds form in the axils of the inner leaves. Root growth intensifies, and the accumulation of stored nutrients increases, laying the groundwork for the development of the bulb and the scape. This stage also accelerates the uptake and utilization of soil nutrients, making it a critical period for garlic’s growth and development.

Late-stage growth of garlic scapes and garlic

From the end of flower bud differentiation to garlic scape harvest, vegetative and reproductive growth proceed in parallel, with the greatest growth rate.

As garlic scapes elongate rapidly, the bulb also gradually forms and expands. During this stage, root growth and nutrient uptake reach their peak, making it the period of highest fertilizer demand and a critical time for fertilization.

Following the harvest of garlic scapes, the bulb enters its peak bulking phase, while the root system begins to senesce. A substantial portion of the nutrients absorbed by the roots, along with stored reserves in the leaves and leaf sheaths, is translocated to the bulb, accelerating its enlargement and filling. At this stage, as both the leaves and roots gradually age, nutrient uptake declines; most of the nutrients required for bulb expansion are derived from the redistribution of the bulb’s own internal reserves.

Macronutrient requirements

During its growth period, garlic requires large amounts of nutrients, primarily nitrogen, phosphorus, and potassium. Throughout the entire growth cycle, it absorbs the most nitrogen, followed by potassium, with phosphorus being absorbed in the smallest quantity.

For every 1,300 kg of garlic produced (the typical yield per mu), 13.4–16.3 kg of nitrogen, 1.9–2.4 kg of phosphorus, 7.1–8.5 kg of potassium, and 1.1–2.1 kg of calcium are required.

Throughout the entire growth cycle, garlic exhibits distinct patterns of nitrogen, phosphorus, and potassium uptake at different developmental stages, characterized by relatively low absorption in the early phase and increased uptake during the mid-to-late stages. The peak periods for nitrogen and potassium uptake occur during bulb enlargement, while phosphorus uptake peaks during the scape elongation stage.

Among the three major nutrients, nitrogen deficiency has the greatest impact on yield, followed by phosphorus deficiency, while potassium deficiency exerts the least effect. When all three nutrients are deficient simultaneously, the negative impact on garlic yield is even more pronounced.

Demand for micronutrients and trace elements

Garlic is sensitive to secondary and micronutrients such as sulfur, calcium, magnesium, copper, boron, zinc, and iron; applying these nutrients in adequate amounts can increase yield and improve quality.

Before bolting, the uptake of the micronutrients boron, iron, manganese, and magnesium reaches its peak; after bolting, the uptake of the three major nutrients and boron once again attains a minor peak, while zinc uptake reaches its maximum.

When garlic is deficient in calcium, necrotic spots appear on the leaves; applying additional calcium can increase bulb yield.

Magnesium deficiency in garlic causes chlorosis of the leaves, which eventually turns yellow and leads to plant death. Applying additional magnesium can rapidly increase bulb yield and enhance the uptake of nitrogen, phosphorus, and potassium, though it may slightly affect calcium absorption.

Sulfur is an essential component of garlic quality. Appropriate sulfur application can enhance garlic flavor and tends to increase bulb weight and promote the elongation of scapes.