Garlic bulbils are miniature, teardrop-shaped structures that develop in the flower head, or umbel, of hardneck garlic varieties. These bulbils are not true seeds, but perfect genetic clones of the parent plant, functioning as tiny, aerial cloves. Gardeners use them primarily to increase planting stock and maintain disease-free lines. Because they mature above ground, bulbils avoid contact with soil-borne pathogens, offering a clean slate for propagation.
Differentiating Bulbils from Cloves
Propagation with bulbils offers distinct advantages over planting individual cloves. A single garlic scape can produce anywhere from a few large bulbils to over 150 small, rice-sized bulbils, providing a massive quantity of planting material. This makes them an economical and efficient way to build up a large inventory of a specific cultivar. Since bulbils never touch the soil until planting, they are an excellent tool for rejuvenating a garlic strain by eliminating common soil-borne diseases and pests.
The significant trade-off for these benefits is the extended time required to achieve a full-sized, usable bulb. A single clove, planted in the fall, will produce a mature, segmented bulb in one growing season. In contrast, a bulbil requires a multi-year commitment, generally taking two or more full growing seasons to yield a bulb of comparable size and complexity. Therefore, while cloves provide immediate annual harvests, bulbils are a long-term investment for stock maintenance and expansion.
Optimal Planting Timing
The optimal planting time for garlic bulbils is in the fall, typically four to six weeks before the ground is expected to freeze solid. This timing is necessary because garlic requires a cold period, known as vernalization, to trigger the hormonal processes needed for proper bulb development. Planting in late autumn allows the bulbils to establish a healthy root system before the onset of winter dormancy.
This cold exposure primes the bulbil for spring growth, leading to the formation of a single, round bulb in the first year. While bulbils can be planted in the early spring, this alternative often bypasses the necessary chilling period, resulting in significantly smaller first-year rounds. Fall planting is strongly recommended in temperate climates to mimic the natural cycle and achieve the best possible first-year growth.
Preparation and Initial Planting Depth
Before planting, separate the tiny bulbils from the umbel’s papery cluster, carefully removing any chaff. Some gardeners choose to soak the bulbils in water for a few hours to encourage germination. The bulbils should be planted very shallowly, generally between one-half inch to one inch deep.
Due to their small size, bulbils can be spaced much more tightly than cloves, with an acceptable spacing range of one-half inch to two inches apart in a designated nursery bed. This tight spacing maximizes the number of rounds produced in a small area. After planting, the bed should be immediately mulched with a layer of straw or chopped leaves for winter protection.
The Multi-Year Harvest Cycle
The unique growth cycle means the first summer’s harvest does not yield a traditional, multi-cloved head of garlic. Instead, the planted bulbil grows into a single, undivided bulb known as a “round.” These rounds are typically small, ranging from one-quarter inch to an inch in diameter, and should be harvested, cured, and stored like mature garlic.
The essential second step is replanting these harvested rounds the following fall, treating them as large, single cloves. The rounds are planted deeper and spaced further apart, at a depth of about two to three inches, with four to six inches between each round. This second full growing season allows the round to finally divide into a segmented, full-sized head of garlic. Therefore, a minimum of two full growing seasons is necessary to transform a bulbil into a mature head of garlic.