The Best Fertilizer for Green Onions

Nutritional Needs

• Because green onions don't spend as long a time in the garden as storage onions, they don't need additional fertilizer as often. To get them off to a good start in all cases, incorporating phosphorous into the soil by placing it in the rows 2 to 3 inches below the seed enhances both growth and yield. Texas A&M Agrilife Extension states that the phosphorous acts as a starter solution that improves seedling growth, and suggests a blend of 0-20-0 superphosphate applied at a rate of 1/2-cup per 10 feet of row. The phosphate should be covered with 2 inches of soil and the seeds sowed on top and covered with an additional 1/2-inch of soil. When established, the plants should be given the same amount of 21-0-0 ammonium sulfate or ammonium nitrate every month as a side dressing along the rows.

Onion Facts

• Onions have the honor of serving a different and specific purpose at all stages of their growth, and any onion can be grown for use as a green onion. They can be started as seeds indoors or directly in the garden from sets, which are small immature bulbs that are either picked as green onions or allowed to mature as storage onions. While any type of onion can be grown and harvested before it reaches maturity, one specific type, Allium fistulosum, is grown specifically as a green onion, or scallion. Started from seeds indoors or directly in the garden, they are sown closely together and are ready to harvest when they are 6 inches tall, as their flavor greatly intensifies beyond that stage.

Culture

• During their establishment in the soil, onions produce very small root systems whose primary function is to anchor them to the soil. Plants with small root systems need soil that is rich in the types of nutrients and minerals that exist near the surface, as most of their energy is devoted to bulb and top formation. Plenty of organic matter such as compost or aged manure should be worked into the area before planting. Grown from regular onion seeds or sets, green onions are ready in six to eight weeks, and any young plants thinned from rows of onions intended for long-term storage can be used as green onions.

Growing Green Onions

• All onions, including green onions, do best in a sunny area with loose, rich well-drained soil with a pH, or acidity level, of between 6.0 and 6.5. A soil test should be performed to accurately assess, not only the acidity level but the soil's fertility as well. Because of their fine roots, onions benefit from being grown in raised beds in areas where the soil is heavy due to a high clay content. The area should be kept weed-free, as onions compete poorly with other vegetation. If growing green, or bunching onions from seed, they should be started four to six weeks before the last spring frost and planted thickly in the cells of growing flats. Once established, the seedling clumps can be transferred to the garden about two weeks before the last frost and spaced about 8 inches apart. If planting directly into the garden, seed should be planted thickly 1/2-inch deep with 12 inches between the rows.