Onion Garden Guide

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Onions

Onion Stat Summary

Plant Spacing: 3-5" (76-127 mm)
Row Spacing: 12-24" (304-609 mm)
Planting Depth: 1/4" (6 mm)
Plants Per Person: 15
Soil Temperature: 50-75°F (10-24°C)
Days to Emergence: 6-16
Recommended Soil PH: 6.2-6.8
Seed Indoors: 10 weeks before transplanting
Earliest Outdoor Planting: Before Last Frost
Tick Can direct seed outdoors
Tick Can seed indoors

Planting Onion

Onions prefer light, fertile, well drained sandy loam soils with a pH of 6.2 to 6.8. Onions can be direct-seeded, grown from transplants started inside, or from sets (small bulbs about 1/2 inch in diameter grown from seed the previous season).

As soon as the soil can be worked in the spring, direct sow 2 to 4 seeds per inch at 1/2 inch depth; space the rows 1 to 2 feet apart. Thin bulb onions to a 3-5 inch spacing between plants. Start transplants inside about 8 to 10 weeks before last frost date. Plant 4 or 5 seeds in each cell, or seed in flats 1/4 inch deep and 1/2 inch apart. If tops grow too tall and begin to droop, trim back to about 3 inches tall with scissors.

After hardening off, transplant in garden at 4 inches apart for large bulbs, 2 inches apart for smaller bulbs, or 1 inch apart for scallions. Choose bulbs no larger than 3/4 inch in diameter for your sets; plant sets about 1 inch deep and 4 inches apart for large bulbs or 2 inches apart for smaller bulbs.

Growing Onion

Young plants require light, frequent irrigation; stop watering when bulbs have reached full size and the tops drop. Watering onions early in the day allows maximum time for the foliage to dry thoroughly

Harvesting and Storing Onion

When the plants mature, the tops naturally fall over; you will interrupt plant growth if you break the tops early, resulting in smaller onion bulbs. Pull the mature onions in the morning and allow the bulbs to air dry in the garden until late afternoon.

Onion Insect and Disease Information

Fungal diseases such as blights, molds and mildews can be minimized by practicing 3 year crop rotations and removing old plant debris in the fall.

Onion Yield Information

No yield information for Onion.