How to Transplant Onion Seedlings

Whether you started onion seeds indoors, or you bought onion seedlings at a garden center, follow these tips for transplanting them into your garden. If your seedlings are pencil-width size, and you choose the right spot and soil conditions for planting, you can have a prize onion crop in a few months.


Best Soil Conditions for Onion Seedlings

When choosing a spot for your onion bed, look for well-drained soil that is not too loose or moist. Clean sandy loam with a pH between 6.6 and 6.8 is the best soil for growing onions. The area should never have puddles of water after watering or rain because onion bulbs rot if sitting in moisture too long. If your soil is too mucky, you can add sand to it, mixing it in with a garden rake.

Before planting your onion seedlings, make sure the soil is free of stones and any other debris. Even coarse gravel can interfere with seedling growth. Take care to pulverize any soil clumps into a fine texture. Incorporating a thick layer of organic manure also adds nutrients to the soil for growing large onions.

How Far Apart to Plant Onion Seedlings

Once you have worked the soil into a soft, loose bed, use the corner of a hoe to make one-inch deep furrows in your garden, spaced about 14-inches apart. This will give plenty of room for large bulbs to grow and provide air circulation to the bulbs. Plant your seedlings three to four inches apart, depending on the cultivar you have. Larger onions need more space.

How to Set the Onion Seedlings in the Soil

If your seedlings have tall, thin stems, you can trim them back to about three-inches tall before planting them. Trimming back the onion stems allows the seedlings to develop a strong root system. Follow these steps for setting your onion seedlings in your furrows:

  • Hold the seedling in your hand and place the seedling root into the furrow.
  • Use your other hand to press the plant into place in the soft soil.
  • Press the soil firmly against the roots.
  • Fill up the hole with soil and smooth it out.
  • Water the seedlings.

Maintaining Onion Seedlings

Water your onion plants weekly but let them dry out between weekly watering. As your seedlings grow, the slender stems will get longer. To maximize growth of your seedlings, weed around the roots regularly, so they don’t block the sunlight from the young plants.

You can hand-pull the weeds or use a hoe around the plants. If any of the seedlings or bulbs should get dislodged fromunderground, just press them back into place. Applying organic mulch around your onion seedlings can help with weed prevention.