Approximately 270 seeds per gram. Allium cepa Lot# ON30011 The Walla Walla onion is considered a long day onion (long-day onions need about 14 to 15 hours of daylight to bulb-short-day onions need 10 hours of daylight). The Walla Walla onion is a medium to large, yellow fleshed, sweet onion. Mature bulbs vary in size from 5-10cm (2-6”). Start seeds indoors as early as you can just to ensure that you have the biggest transplants available for spring planting. Seeds can be planted either in the spring for fall harvesting or in August for over wintering. Walla Walla onions are hardy to -23 °C (-10°F). Spring planted Walla Walla sweet onion seeds result in bulbs that are not quite as mild as the overwintered ones and may not size up as well. They are not a long-term storage onion so enjoy them fresh.
Start indoors in February to mid-March, and transplant in April. Scallions can be direct sown every 3 weeks from April to late August. Sow 3 seeds 6mm-12mm (¼-½") deep in each cell of a 72-cell tray. Transplant spacing for cells should be around 12-15cm (5-6") apart in rows that are 45-75cm (18-30") apart. You may sow seeds directly into garden. The soil should be moist before sowing so check the soil the day before sowing and water if the soil is dry. We string our rows about 30cm (4”) apart and 15.2m (50’) long and etch a furrow about 5mm-12mm deep and drop about 2-4 seeds per 2.5cm (1”). Cover lightly with soil. Thin to about 10cm apart when onions reach about 5 cm in height. If planting onion sets, wait until soil can be worked thoroughly in the spring. A well worked, loose soil is best for planting onion sets. If soil is nice and loose, you can just push the onion set into the soil with necks upwards and cover, leaving just the top of the neck poking out of the soil.
Height at Maturity: Walla Walla Onions grow to +70cm (27.5”) tall. Spread: 10-15cm (4-6”).
Days to Maturity: 150 days for maturity from spring sown. 300 days for fall sown.
Watering: An inch of water a week ensures good growth, whether vegetables are grown in single or wide rows. The amount of rain that falls during the week affects how much you should water your garden. Keep soil consistently moist until bulbs enlarge and mature. Onion roots are shallow; so a light watering will suffice.
Sun/Shade: Full Sun
Spacing after Thinning: 12-15cm (5-6") apart in rows that are 45-75cm (18-30") apart.
Additional Information Pull onions at any stage for fresh eating. Harvest young onions to eat as scallions. For full-sized bulbs, don’t pull onions until bulbs are big and tops start to yellow and fall over. To harvest, pull onions and shake off soil. Cure onions in a warm, dry place with lots of air flow. During curing, roots shrivel and necks dry and tighten. After 7 to 10 days of air curing, cut off onion tops and trim off roots with snipers or scissors. Carefully rub dry dirt from bulbs, taking extra care not to remove papery outer skins from the bulb. Temperature: Onions will last the longest in a dark, cool (but not cold), dry storage area. Don't ever store onions in plastic bags. Potatoes and onions should not be stored together.