Onion Sprouts are Not Germinating

Season and Temperature

• Onions are summer and fall crops and do best with early spring starts and cool, moist weather for germination. According to the Ohio State University Extension, onion seeds germinate best at 55 to 75 degrees Fahrenheit. The University of Minnesota Extension suggests starting onions when ground temperatures reach 48 degrees F. Colder temperatures restrict the seeds' ability to germinate.

Site and Sun

• Onions need the warmth and light of the sun to germinate and grow successfully. Deep shade restricts plant activity and may retard germination. Plant the onion seeds in sites with full sunshine and quick drainage for best results. Plant them 1/2-inch deep and space them every 3 inches in the row.

Soil

• All seeds require moist, crumbly and loose soil for germination; tight or dry soil restricts the seeds' ability to push apart and produce roots. Amend the soil with plenty of organic compost at planting for a loose, nutritious foundation. Add 5-10-10 granular fertilizer to encourage optimal root production in the seeds.

Moisture

• Seeds won't germinate without adequate water, and cool-season crops, such as onions, require more consistent watering to thrive. Give them 1 inch of water every week and monitor the soil; if it dries out between waterings, increase your schedule to 1 inch of water every four to five days. Till the soil regularly with a hand fork to prevent crusting on the surface as this restricts sprouting.

Viability

• Seeds may sprout or not, depending on their viability at planting. Seeds with dead plant matter cannot germinate, regardless of the conditions around them. Always test vegetable seeds for viability before planting by putting them in a glass of water. Seeds that sink are viable and ready for planting; seeds that float are dead.