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Growing Onions

 

  • Ideal Soil pH: 6.0 - 7.0

  • Ideal Climate: Temperate (cool-season) 55 - 75 degrees Fahrenheit

  • Daily sunlight for mature plants: 6+ hours full sun

  • Watering mature plants: Regular moderate watering (every 1 to 2 days) 

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Step 1: Choosing a Location to Plant Onions

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Onions require full sun for at least six hours per day to thrive. Choose a planting location that receives ample sunlight, preferably in a spot with southern or western exposure. Avoid areas shaded by buildings, trees, or other structures. Onions have shallow root systems and can be easily damaged by strong winds. Plant onions in a location protected from strong winds, such as near a fence, building, or windbreak. Providing wind protection helps prevent lodging and damage to foliage.

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Step 2: Choosing Onions to Grow

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Onions can be grown from seed, sets (small bulbs), or transplants (seedlings). Consider your preferred method of propagation and the time available for growing onions. Growing from sets or transplants can save time and yield earlier harvests, while growing from seed offers a broader selection of varieties and potentially higher yields. Onions are categorized into three main types based on their response to day length: short-day, long-day, and intermediate-day varieties. Choose the type that corresponds to the length of daylight in your region. Short-day onions are suited to regions with mild winters and shorter days, while long-day onions are best for areas with longer days and cooler temperatures. Intermediate-day onions fall between these two categories and are suitable for regions with moderate day lengths. Onions come in various colors, including white, yellow, and red. Consider the color preference for your culinary needs or market preferences. Yellow onions are versatile and have a mild to medium flavor, while red onions add color and a slightly sweeter taste to dishes. White onions have a mild flavor and are often used in Mexican cuisine and salads.

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Where to Get Onion Bulbs

Onion bulbs are easy to find at almost any home improvement or garden store. As always, there are almost an unlimited amount of varieties online and it is always best to opt for organic if you can.

Step 3: Preparing Soil for Growing Onions

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Clear the planting area of any weeds, rocks, or debris. Loosen the soil to a depth of at least 6 to 8 inches (15 to 20 cm) using a garden fork or tiller. Break up any clumps and remove any large stones or roots. Improve soil fertility and structure by incorporating organic matter such as compost, well-rotted manure, or aged composted leaves into the soil. Spread a 2- to 3-inch (5- to 7.5-cm) layer of organic matter over the planting area and mix it thoroughly into the soil. If you have heavy or poorly draining soil, consider planting onions in raised beds to improve drainage and provide better growing conditions. Construct raised beds using untreated lumber or other suitable materials and fill them with a mixture of topsoil, compost, and other amendments.

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Step 4: Planting Onion Bulbs

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Plant onion bulbs in early spring, as soon as the soil is workable and temperatures are consistently above freezing. Onions prefer cool weather for establishment and growth. Space onion bulbs 4 to 6 inches (10 to 15 cm) apart in rows spaced 12 to 18 inches (30 to 45 cm) apart. This spacing provides enough room for the bulbs to grow and mature without overcrowding. Plant onion bulbs with the pointed end facing upward and the root end facing downward. Place the bulbs in shallow planting holes or furrows, with the tops of the bulbs level with the soil surface. Planting depth should be approximately 1 inch (2.5 cm) deep. If planting individual bulbs, gently press them into the soil until they are secure. If planting in rows, create furrows with a hoe or trowel and place the bulbs in the furrows, spacing them evenly. Cover the bulbs with soil and lightly firm the soil around them. After planting, water the soil thoroughly to settle it around the bulbs and provide moisture for germination. Ensure the soil remains consistently moist but not waterlogged during the establishment period. Apply a layer of organic mulch, such as straw or shredded leaves, around the base of onion plants to conserve soil moisture, suppress weeds, and regulate soil temperature. Leave a gap between the mulch and the onion plants to prevent rot and disease.

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Step 5: Watering Onions

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Mature onion plants prefer evenly moist soil, but they are susceptible to rot if the soil becomes waterlogged. Check the soil moisture regularly by inserting your finger into the soil near the base of the plants. If the soil feels dry to the touch, it's time to water. Water mature onion plants deeply but infrequently. Aim to provide enough water to penetrate the soil to a depth of 6 to 8 inches (15 to 20 cm) with each watering. Watering once or twice a week is usually sufficient, depending on weather conditions and soil moisture levels.

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Its best to water in the morning hours when the moisture is able to penetrate the soil before it evaporates. It is also good practice to focus the watering around the base of the plant and avoid watering the foliage to reduce the chance of diseases developing.

Step 6: Fertilizing Lettuce

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Once onions are established and have started to produce foliage, consider side-dressing with additional fertilizer to support their growth. Side-dressing involves applying fertilizer to the soil around the base of the plants, away from the stems, and then lightly incorporating it into the soil surface. Use a nitrogen-rich fertilizer, such as ammonium sulfate or calcium nitrate, for side-dressing onions to encourage leafy growth and bulb development. Apply fertilizer every 3 to 4 weeks throughout the growing season, starting from early spring until the bulbs begin to mature. Monitor the onions' growth and adjust the frequency of fertilization based on their nutrient needs and soil conditions.

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Step 7: Harvesting Lettuce

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Monitor the foliage of the onion plants as they mature. When most of the leaves have turned yellow and started to flop over at the neck, it's a sign that the onions are nearing maturity and ready for harvest. This typically occurs in late summer to early fall, depending on the variety and growing conditions. Check the size of the onion bulbs to determine if they're ready for harvest. Mature onions will have reached their full size and should feel firm to the touch. Avoid harvesting onions that are still small or underdeveloped, as they may not have reached their full potential. As onions mature, the necks (stems) above the bulbs will begin to soften and bend over. This is a natural sign that the onions are ready for harvest. However, if the necks are still firm and upright, the onions may need more time to mature. Mature onions will have developed a papery outer skin that feels tight and dry. Avoid harvesting onions with loose or shriveled skin, as they may not store well.

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