Green onions, also known as scallions or spring onions, are a fantastic entry point into indoor gardening. Their slender form and modest root system make them perfectly suited for small containers and windowsills. Using kitchen scraps to initiate growth is a simple, rewarding method that provides a continuous supply of this mild, flavorful garnish. This approach is highly sustainable, allowing you to harvest fresh greens exactly when a recipe calls for them.
Starting Your Green Onions: Scraps Versus Seed
The two primary ways to begin growing green onions indoors are starting from seed or regrowing them from the white root base of store-bought scraps. Regrowing from scraps is the most popular and immediate method for indoor cultivation. To start, cut the green stalks off about one inch above the white bulb and root plate, reserving the bottom portion.
You can place these root ends upright in a small glass jar or container with about a half-inch of water, ensuring only the root tips are submerged. New green growth often appears within 24 to 48 hours, and new white roots develop in a few days. Planting seeds is possible but requires a much longer waiting period of 50 to 60 days before the first harvest.
The scrap method requires changing the water every few days to prevent root rot and keep the environment clean. While the scraps can begin regrowing in water, they must eventually be transferred to soil to continue thriving. The water alone does not contain the necessary nutrients for sustained growth. Planting the rooted scraps into a well-draining pot provides the minerals and stability needed for multiple future harvests.
Creating the Optimal Indoor Environment
Once your root scraps have established new roots, or your seeds have sprouted, the green onions need an optimal indoor environment. The most common factor limiting indoor growth is insufficient light, as green onions require a minimum of six hours of bright light daily. A sunny, south-facing windowsill is the best natural light source, but the plants should be rotated every few days to encourage even growth.
If natural light is limited, supplementing with a full-spectrum LED grow light is necessary to provide the 10 to 12 hours of light they prefer. Position the light source a few inches above the growing stalks and adjust its height as the onions lengthen. Green onions prefer a standard indoor temperature range, ideally between 60°F and 75°F, and should be kept away from cold drafts or direct heat.
For the growing medium, a well-draining potting mix is best, as it provides both anchorage and nutrients for long-term health. The container must have drainage holes to prevent the soil from becoming waterlogged, which leads to root rot. The soil needs to be kept consistently moist but never soggy, often requiring watering every two to three days.
Techniques for Continuous Harvesting
The ability to harvest green onions repeatedly without pulling up the entire plant relies on the plant’s natural ability to regenerate leaves from the basal plate. For a continuous supply, employ the “cut-and-come-again” method when the stalks reach a usable length, typically six to eight inches.
Using sharp scissors or a knife, snip the green stalks about one to two inches above the soil line or the white base. This technique leaves the root system and the growing point intact, stimulating the plant to quickly sprout new leaves from the center. You can expect significant regrowth within a week, allowing you to harvest from the same plant multiple times.
The plant will eventually exhaust the energy stored in the original bulb, typically after three to five harvests, resulting in thinner, weaker regrowth. At this point, the plant should be composted and replaced with a new set of root scraps or a fresh planting. To support sustained productivity, lightly fertilize the soil-grown onions with a balanced liquid fertilizer every few weeks.