How long do onions take to mature
However, they have no lateral roots, so space them just 2 to 3 inches apart. You can try hlw in radish seeds both to mark the planted rows and as a trap crop to lure root maggots away from the onions. Long-day types, like 'Sweet Sandwich' and 'Southport Red Globe', need 13 to 16 hours of summer daylight in order to form bulbs. In spring, apply a nitrogen-rich fertiliser to autumn-planted bulbs to give them a boost. Pests how long do onions take to mature Diseases. When your seedlings are about 3-inches tall, transplant them to your garden.