Planting Onion Sets in Seed Trays
Planting onion sets in seed trays or cells is a valuable approach for getting a head start on next year’s harvest. This method offers a controlled environment that promotes healthy growth, protects young sets from frost, and reduces losses from pests—particularly birds that can pull young sets out before they have a chance to root. Seed trays can be kept in a greenhouse or sheltered area, allowing for better management of moisture levels, which is crucial for young plants. This environment helps ensure optimal conditions for germination and early growth, giving your onions a better chance of thriving when transplanted.
Step-by-Step Guide to Planting Onion Sets in Trays
Follow these steps for successful onion set planting:
1. Mix together multipurpose compost (John Innes No.1) and Perlite at a ratio of 3:1. This mix of growing media will hold moisture whilst ensuring adequate drainage.
2. Fill each cell with the compost mixture, pressing lightly to create a firm base for your set without compacting the soil.
3. Use a dibber to make a hole in each cell deep enough to accommodate most of the onion set, with just the tip protruding above the surface.
4. Place the onion set in the hole with the basal plate (flat end) facing downwards, ensuring the top of the set remains just visible above the soil. Gently firm the compost around the set to ensure it’s well-supported on all sides, avoiding excessive pressure that could damage the basal plate.
5. Give the tray a good watering to settle the compost around the sets.
Once you’ve sown your onion sets in seed trays, it’s essential to place the trays in a greenhouse or a cold frame. This provides a warm, sheltered environment that fosters healthy growth. Maintain a consistent moisture level in the compost, ensuring it doesn’t dry out, but avoid waterlogging.
