Onions, known for their culinary significance, are not only a flavorful addition to various dishes but also a beginner-friendly choice for aspiring gardeners. With the convenience of a Poly greenhouse, you can now enjoy the satisfaction of harvesting top-quality onions right from the comfort of your home. In this guide, we'll walk you through the process of growing onions in your greenhouse, from soil preparation to selecting the right varieties.
Soil Requirements for Growing Onions in house farming The foundation of successful onion cultivation lies in the soil. Compacted soil should be avoided, and maintaining a pH level between 5.8 and 6.6 is crucial. Sandy loams and muck soils are often preferred for onion cultivation, and if you're aiming for sweet Spanish onions, ensure the soil's sulfur levels are below 40 ppm.
Temperature Requirements in the Greenhouse for Growing Onions Understanding your onions' temperature preferences is pivotal for a successful harvest. These winter plants flourish within a temperature range of 12.7°C to 23.8°C. As you embark on the onion-growing journey, it's essential to tailor your greenhouse's temperature settings accordingly, particularly during the crucial bulb formation stage. Employing heaters or evaporative coolers within the greenhouse can help you maintain the ideal temperature range. Expect onion germination to occur over 6 to 12 days, and make sure to adjust the daytime temperature within the greenhouse from 15.5°C to 18.3°C.
Onion Varieties Suitable for Growing in Greenhouse Selecting the right onion variety is akin to choosing the paint colors for your canvas. Here are a few noteworthy options that thrive within the controlled environment of a greenhouse:
- Long-day Varieties
- Yellow Sweet Spanish: Recognized for their large, round shape and yellow-white hue.
- First Edition: This variety boasts high yields, excellent storage capabilities, and a flavorful creamy-yellow composition.
- Red Wethersfield: With its red-skinned, white-fleshed, and flat bulbs, this onion is a great storage option.
- Ailsa Craig and Walla Walla: These varieties produce huge bulbs that are hard to miss.
- Buffalo and Norstar: While they offer early yields, they keep well only until late December.
- Copra, Southport Red Globe, Sweet Sandwich, Yellow Globe: These varieties excel at extended storage.
Red Florence: Known for its oblong shape and rich color.
Planting the Onion Sets Inside Your Greenhouse
- Preparing the soil is a critical step in setting the stage for onion growth. Follow these steps to ensure a successful planting process:
- Spread one to two inches of compost across the soil bed.
- Incorporate the compost into the top six to eight inches of soil using a rototiller and smooth the soil surface with a rake.
- Create a 4-inch wide and deep trench using a trowel.
- Sprinkle 10-20-10 granular fertilizer at a rate of 1/2 cup per ten feet along the trench's bottom.
- Cover the fertilizer with soil, ensuring a 2-inch layer on top.
- Firmly press down the soil in the trench.
- Plant the onion sets with their rounded ends facing the ground and pointed ends upwards.