Onion sets are considerably more expensive than onion seeds. Nevertheless, I mostly use onion sets. Since spring is usually quite dry here and onion sets require a lot of water before they develop roots, I've developed a method to give them a better start in life and require less water.
At the end of February or beginning of March, I plant onion sets in soil-filled pots in seed trays, water thoroughly, and place them in the greenhouse. There, they develop roots and the first few centimeters of green bulbs until I plant them in the garden around the end of March. The advantage: The number of onion sets that don't sprout is very low.
To plant, I use a bulb planter to dig a hole in the soil and place the bulbs, complete with their roots, in it, leaving one-third of the bulbs exposed. Then I press them down a bit, water them, and mulch them.
