Planting and Growing Onions

Onions can be red, yellow, or white. Each color has different uses in the kitchen.

This page gives tips on planting and growing onions with many helpful tips and advice based on David's own experiences. This page also includes bunching onions.

Onions come in several day lengths: Long Day, Short Day and Intermediate Day.

Onion bulbing is triggered by day length, and maximum day length during the growing season increases from south to north. Short-day onions are grown at lower latitudes in the south, while intermediate and long-day onions are grown at higher latitudes.

Short day onions need 10 to 12 hours of sunlight and are usually planted in the fall. They overwinter and you can harvest them in early spring.

Intermediate onions aka day neutral onions need 12 to 14 hours of sunlight and are usually planted in the fall.

Long day onions need 14 to 16 hours of sunlight and should be planted in early spring.

Usually, when planting onions, you will have two choices: Sets or seeds. With sets you can get about 25 to 50 plants ready to go for about 5 to 6 dollars. All you have to do is plant them, about an inch deep, and they will grow. They will need to be planted about six inches apart.

There are many videos and websites that talk about how to do this. The one I recommended is Dixondale Farms located in Carrizo Springs, TX just about a two hour drive from our location. The sets are actually called bunches. 

Before you begin, read our pages on Germination and Calories in Onions so you can learn what day-length means. And you may also want to look at our page on Soil Testing.

Once you have chosen your onion seeds, you are ready to plant them.

Onions require full sun and fertile, well-drained soil with a pH of 6.0–7.0. Sandy loam soils are ideal; in heavier soils, use raised beds or raised rows to promote soil drainage. So our sandy soil is perfect for growing onions. 

Actually our crop came out really good. We do not fertilize more and water more since the sand does not hold these elements as long as regular dirt does. The problem we had was we had a new person harvest them. The  instructions were to pull the onions up and lay them down where they were harvested for drying. We had to be at the store in San Antonio so we were not able to be out here while they harvested them.

When we arrived home that evening, I noticed that they had gathered the onions up and cut the top/bottom off and put them in a bucket. Without drying properly, they would not store properly.  They were invited not to come back. I tell the team members, inside workers and outside workers, that they need to do exactly what we say. No more and no less. At least until they know what they are doing.

Planting And Growing Onions In Your Garden

Plant your seeds 1/4 to 1/2 inch deep. 1/4 is probably best. Space them 2 inches apart because not every seed will come up. Or if you do not want to thin, plant them 4 to 6 inches apart. The further apart they are, the bigger the onion.

Make sure the soil is at least 70 degrees before planting. If you have highs in the 70s, lows in the 40s, your seeds will probably not germinate. Needs to be a constant 70 degrees.

Use soaker hose so that the seeds do not dislodge from using a sprinkler hose. If you get a heavy rain, you will probably need to replant.

When gardeners email me and say that their seeds did not germinate and that they are no good, the second thing I look at is the weather. Every time there has been a complaint, the weather has not been warm enough.  I know it is hard and we get antsy to plant, especially if there are some warm days, but the bottom line is the seeds will not germinate in cool soil.

The first thing I ask is how deep did they plant. Usually they have planted too deep. By the way, we recommend planting seeds 1/4 to 1/2 inch deep.

The seeds will germinate in about two weeks or so. When they come up you can change to a different type of water system. We use a fogg-it nozzle. It puts out a gentle spray so it is good for both germination and sustained growing. We love them. Of course, if the wind is blowing strong in one direction then part of the garden does not get watered.

We have had no problems with disease or insects with our onions. We use the 3 in 1 Safer soap which seems to keep our garden free and clear of all insects and fungi.

Once the necks start to brown and fall over, it is time to pull them up and sun dry them for a few rain free days. After a few days, gather them up and put them in a protected area for about two more weeks.

How long your onions keep depends on how you treat them after harvest. After they have dried in the field for a couple of days, it is recommended that they continue the drying process in a shed, garage, or other cool, shaded location. Be sure the location is well-ventilated so they can breathe. The entire neck (where the leaves meet the bulb) should be dry, all the way to the surface of the onion, and shouldn't "slide" when you pinch it. The skin will take on a uniform texture and color. This is how you know they are done drying.

Once the onions are thoroughly dry, clip the roots and cut back the tops to one inch. Now they are ready to eat.

Store onions in a cool, dry, well-ventilated location, such as a garage or cellar. Place them in mesh bags or netting to permit airflow. Periodically check for any soft onions, and remove them to avoid deterioration of the others. As a general rule, sweeter onions don't store as long as more pungent ones, so use the sweeter onions first.

Our onion crop lasted six months before they started turning soft. They got a black mold on them, but it caused no problems.