Soil Preference

Soil PH: 6.0-7.5, Ideal 6.8-7.0

Onions don't need a lot of nutrients, but they aren't very efficient feeders (their roots are weak and shallow), so you have make sure they have plenty available. For example, they only need about 150 pounds of nitrogen per acre, but you may have to add 300 pounds for them to get even that much.

Onions do best in a loose, rich, moisture retentive soil with lots of organic matter. They don't like compacted, heavy, dry, acid, salty, or poorly drained soils (their roots may rot if it is too wet).

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Soil Preparation

Lime (Calcium), 5 pound(s) per 100 sq. ft., in top 6in of soil, 1 time

OPTIONAL: Onions don't like acidic soil, so add dolomitic limestone if necessary. The quantity needed will vary according to soil type, but 5 pounds per 100 square feet is a typical application.

Standard Mix, 5 pound(s) per 100 sq. ft., in top 6in of soil, 1 time

A standard mix will supply any additional nutrients required. Incorporate it into the soil along with the compost.

Compost (N), 2 inch(es), in top 6in of soil, 1 time

Prepare the soil by incorporating 2˝ of compost or aged manure into the top 6˝ of soil, which is where most of their feeder roots are to be found.

For an early spring planting you could do this in fall, using fresh manure if necessary.