Seed To Table – Onions

Posted on December 28, 2010 by ediblesanmarcos | Edit


The history of onion is one that is so unclear as wild onions have been growing for centuries. Most archeologists agree that bulb onions originated in central Asia.

One thing that we can say for certain is that onions have been cultivated for over 5000 years.  In 3500 B.C. there were onions growing in Chinese gardens. In 2500 B.C. there was a Sumerian text text that told of a person plowing over the governor’s onion patch.

Onions were used as an object of worship in Egypt as they symbolized eternity. Why an onion you may ask.  It was because of the structure of an onion being a circle within a circle. The onions were painted in pyramids and used at banquet tables as well.

Indians, Greeks and Romans alike all used onions for its medicinal values.  Some may have gone a little too far, such as the Greeks by rubbing their bodies down in onion juice before competition. They probably chased the competition away with the smell!

The Romans brought the onions to England and Germany. From England the bulb onions came to America.  Bulb onions were planted in America in 1648. However the Native American Indians were eating wild onions called ramps.


What you see on top is what is happening below. For each leaf on the onion plant there is a ring of onion below.  The larger the leaf is the larger the onion ring is!  Onions form tops first and depending on the variety they then form bulbs.

Onion sets are actual onion bulbs that have reached one inch in diameter and then have been pulled to stop growing.  Onion transplants are onions that have been growing about 2 months

There are two different varieties of onions, short day varieties and long day varieties.  Long Day Varieties are for the North(North of the 36th Parallel) and start forming the bulbs when the day length reaches 14 to 16 hours. Short Day varieties are for the South and start to bulb when the day length reaches 10 to 12 hours.

There are other varieties of onions that you can grow to add variety to your dishes.

Egyptian Walking Onions Produce a small bunching onion on the bottom and a  small onion on the top that falls over and walks.

Potato Onions are a bunching onion that is a larger than a bunching onion  or a shallot and produces a hill of onions.

Shallots are a bit more pungent and divide, they also like a drier environment.

Bunching Onions produce a large green top and a small shallot on the bottom.  The beauty of bunching onions is that they produce nice fresh green onions in the winter and spring time while you are waiting for your main crop of onions to come into fruition.

Onions prefer a soil Ph that is between 6.2 and 6.8.

Beans and peas do not like onions so beware of that when you are planning your garden.

You need to choose a sunny location to grow onions. Plan your rows the same direction as the prevailing wind to prevent diseases. This will help you keep your onions aired out the natural way.  Onions need fertilizer when you plant them. They like fertilizer with a high phosphorus content.  It is good to add one inch of well rotted compost as well.  Other good sources of amendments are Gypsum which add calcium and sulphur and loosen the soil.  Colloidal phosphate adds phosphorus  and calcium which is needed for good root structure. Greensand or granite meal are good sources of potassium. Dig a trench that is 4” deep. Put the fertilizer in the trench and then cover with 2 inches of soil. Plant the onions 1” deep and 4” apart. Water well.  You need to fertilize again 3 weeks after planting, and again 2 to 3 weeks later. Continue watering and feeding the onions as they have a very shallow root system.  When the neck starts to feel soft, and the ground starts to crack and the bulbs start to form hold back on the water and on the fertilizer.

Cultivate regularly to keep the weeds at bay as they will hinder growth.  Remember that the onions roots are shallow so be very careful. Do not cover the onion bulb with soil or it will hinder bulb formation.

Covering the ground with mulch or straw can help to retain moisture and prevent weeds as well.


Harvest the onion when the tops turn yellow or brown and fall over.  Pull the onions and let cure for 2 days in the field. Make sure when you pull your onions that they are not in the scorching sun or they will get sunscald.  There is a method called shingling that is used to prevent sunscald. When you pull your onions make a windrow.  Then take the tops of one row to cover the next. You can also dry them under a shady tree or in the garage.  Drying in either of these methods will take a few days longer but you will not get sunscald and hence you will not be open to a host of  other fungal diseases. Bring them in and let them dry fully on screens.  Once dry clip the top and the roots to 1 inch. Store the onions in a mesh bag or wrapped in aluminum foil in the refrigerator.

I have compiled a complete list of diseases and insect that can attack your crop of onions.  There are links to follow so you can see pictures and read about the various diseases.  If I would have written about them all this would have been the longest onion article in history and you would have been bored out of your mind! So use this as a reference if you get in trouble.  Remember to rotate your crops.  I can never say it enough and I know you may be tired of hearing it.


Purple Blotch – Purple lesions on the leaves

Blue Mold

Downy Mildew

Bacterial Soft Rot

Basal Plate Rot

Botrytis Bulb Rot

Black Mold


Mushy Rot

Neck Rot

Onion Rust

Pink Root


Powdery Mildew


Sour Skin

Southern Blight

Stemphylium Leaf Blight


White Rot

Tip Blight


Onion Thrip – A sucking insect that rasps the leaves. Thrips cause the onion leaves to turn grey. Thrips look like dark or yellow specks.  Use insecticidal soap.

Onion Maggots

Root Knot Nematode

Lesion Nematode

Stem and Bulb Nematode

Garden Springtail

Lesser Bulb Fly

Onion Recipes




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