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How to Grow Onions The Organic Way

  • Writer: Marshall Grain Co.
    Marshall Grain Co.
  • May 8, 2018
  • 10 min read

Updated: Feb 1

THE LONG AND SHORT OF GROWING ONIONS

 “What a difference a day makes.” That’s especially true when it comes to growing onions, since this versatile vegetable forms bulbs in response to the length of the day.  There are three types of onions and each one is better suited for growing in different regions of the country. “Long-day” onion varieties will quit forming tops and begin to form bulbs when the day length reaches 14 to 16 hours. “Short-day” onions will start making bulbs much earlier in the year when there are only 10 to 12 hours of daylight. There also are day-neutral onions and as the name suggests, regardless of the number of daylight hours, you can count on them to form bulbs. Here in North Texas short-day onions work best.


Onions are biennial, which means that it takes two full years to grow an onion from seed to bulb. No wonder most people prefer to start with transplants.


In this article and accompanying video, you'll learn everything you need to know about how to grow onions in North Texas


Skip to the end of this article to see a transcript of the video.




When to Plant Onions in North Texas

Transplants are available as either small (immature) bulbs — called “buttons” or as “slips.” To produce the largest, best tasting bulbs, you must get those transplants into the ground early. Onions must be properly chilled in the ground. For buttons this means early fall (usually before October 15). Slips should be planted in late December or early January when day length and temperature are just right. Most gardeners prefer to grow their plants from slips.

Onions take two full years to mature, so most gardeners start with buttons or slips. Buttons (L) are small, immature bulbs.


Slips are also immature onions that have already begun to form tops. Green onions are onions that have been harvested at the “slip” stage.



Texas Favorites

  • 1015Y Texas SuperSweet — Large, sweet yellow onion. Matures early. Very disease resistant and keeps better than most other short day onions

  • Yellow Granex (Vidalia) — This large, sweet yellow variety is the earliest-maturing variety available. Best eaten raw. Also known as the Maui or Noonday onion.

  • White Granex — White Vidalia type sweet onion.

  • White Bermuda (Crystal Wax) — Great for bunching or for eating raw. White Bermudas are extremely mild but do not store well.

  • Red (Burgundy) Bermuda — Mild and sweet. Great for sandwiches.


Where to Plant

Like most vegetables, onions must be planted in full sun. Full sun is generally considered to be 6 hours or more of direct daylight. Less than that and your bulbs may not form properly in time for harvest.


Prepare Your Beds

Onions need loose, well-drained soil. Raised beds are best. Dense clay soils should be heavily amended with good quality organic compost and lava sand, expanded shale, Texas Greensand or other soil amendments that improve soil porosity and moisture retention.


How to Plant

Onions are slow growers. As mentioned above, planting from seed takes two full years. Green onions can be ready in 20 to 30 days after planting but dry bulb onions can take 100 to 175 days to reach maturity.


Tip: Plant your onions close together. As they sprout, you can thin them out and eat the harvested slips as green onions. Meanwhile, the rest are left in the ground to mature.


Some gardeners like to dig trenches and then just line the plants up in the trench. Other people prefer to make a separate hole for each plant. Either way, include some soft rock phosphate with each plant.


Push each button or slip into the ground about two inches deep.  Buttons should be planted with the pointy end up.


Keep rows about 12 inches apart and each transplant about five inches apart. The area around each transplant should be about 6 to 12 inches for the onion bulb to grow. Water regularly and thoroughly. Be careful not to overwater. If the soil remains wet, your plants will rot in the ground.


After planting, top dress with compost and mulch.


Care and Maintenance

Keep in mind that the edible portion of the plant is the bulb. If you’re an onion, proper bulb development is everything.


We’ve already discussed the three most important factors: choosing short day varieties and cold weather planting. The third factor is fertilization.


Onions prefer a high nitrogen fertilizer — nitrogen actually helps lower the pH of your soil, which helps with bulb formation. A couple of good fertilizer choices would cottonseed meal or alfalfa meal. Fertilize every two weeks during the growing season.


Keep beds free of weeds. Mulching will help repress weeds and retain moisture.


Pests and Diseases

The most common problems with onions are blight, purple blotch, and thrips.

Both blight and purple blotch are caused by fungus, and are generally caused by excessive moisture (over watering!) Allow the soil to dry out between waterings. Use your finger to check the soil. Push it down to at least the second knuckle. If the soil is still moist, don’t water.

Onions infected with blight. (R)


Onion crops should be rotated every year to prevent the spread of these diseases

Thrips are tiny insects that suck the juices out of the plant. They’re easily controlled with organic insecticidal soap or 70% Neem extract.


Thrips live off the juices of the plant.



Harvesting and storing onions

Stop fertilizing onions when they begin to push the soil away and start the bulbing process. The onion will first form a top and then, depending on the onion variety and length of daylight, start to form the bulb.


The size of the onion bulb is determined by the number and size of the green stocks or tops at the time of bulb maturity. For each leaf there will be a ring of onion — the larger the leaf, the larger the ring will be.


You can harvest them early – in which case you would have green onions or scallions – but you need to eat them right away. They cannot be stored unless they are fully mature at the time of harvest.


When onions are fully mature and have stopped developing, the tops will wither and die. Wait until most of the tops have fallen over. This indicates that the plant is going into dormancy.


At this stage, stop watering and leave the onions in the ground for another 7 to 14 days to allow them to mature fully.


Dig carefully!

Bulb plants such as onions need to be removed very carefully. Use a gardening fork to gently dig under the plant and lift it to the surface. If you try to pull it out by the top, most likely the top will just break off. You want to avoid damaging it. If you damage the skin you can ruin the plant.


Proper drying of onions is essential – otherwise they will quickly rot. Hang in a cool, dry place for at least 1 week before using them.


Onions must be properly dried before storing. A popular way to store them is to braid the tops together and hang them in your kitchen.


Check harvested bulbs for any damage. Soft bulbs indicate internal rot. Throw out any bad ones immediately.


Allow onions to dry for several weeks before you store them. Spread them out on an open screen off the ground to dry. Store at 40 to 50 degrees F in braids or with the stems broken off.  Mature, dry-skinned bulbs like it cool and dry.


Visit us for all the supplies you need to grow bigger, better onions. Then let our staff show you how to have a “no tears” growing experience.


Video Transcript


My name is Patricia, and I work for Marshall Grain, and I love working here. Today we are going to talk about planting onions. There are two different ways you can plant them.


You can plant them in a furrow, or you can plant them in a pot. In a pot, you want to stick your finger down just above your second knuckle. And this will prevent the roots from jaying up on you.


It will go down into the hole, like that. And that's how you plant in a pot. And then with a furrow, you'll want to dig a straight line through.


And then you'll lay the onions on their sides like this. And you can also mass plant them so that as these start to grow, you can pull every other one out, and you'll have your green onion. Or you can just clip off the top, leave this in there, grow a little bigger to make it your scallion.


And then you bring the soil up and over the onion. It went better the first time. And then you bring them up.


And this also helps from the roots jaying, like that. So this is your furrow planting. You're going to want to make sure you water in very good, moist, but not wet.


You do not want them sitting in water. They will rot. After you've planted them, you're going to do your fertilizer.


Is that the sulfur? No, this is the fertilizer. You want high nitrogen. And when you do it, don't pour it directly on the plant.


You're going to want to pour it along the edge and let it soak in.


Pests & Diseases

There's two things about onions that will damage them. It's thrips.


They're very susceptible to thrips. They feed off of the juices of the leaves and in the fold. This is organic.


It's the best for any type of insects, pesticides, fungicides, things like that. And as mentioned before, they are susceptible to rot (from fungal blight). You've seen onions at the grocery store where they're kind of gray and moist. That is due to overwatering. You can also use neem. Neem is a good go-to. And most people are familiar with neem.


Okay, do we have any questions on that part?


Participant Question:

If you're companion planting with the onions, would you lay the onions first and then do your companion planting afterwards? Or if you're growing a bed such as that where you're having maybe a pepper tree in between that or something, would you do it at the same time as you're doing the onions?


Yes, you can do them at the same time. Even if you wanted to plant flowers in between to designate which type of onion.


Say you had red onions, a yellow onion, you can plant another companion crop in between them. Really just to designate which type of onion you've got. And if you want to do peppers, you can do peppers.


Garlic, you can do garlic.


Now that he mentioned that, you can do onions from seed, but they take a year. They take a long time.


Participant Comment:

I thought they took two years. Now we've got our onions and we're ready to harvest them. The best way to harvest is to very gently dig around them, bring them up to the surface and leave them sit for a couple of days until they kind of dry out a little bit.


And then you want to put them in a cool, dry place in an aerated bag, like an onion bag or something that has aeration for them. How long do you harvest? It depends. You have your short days and long days.


All the plants that we have are short days, so they're going to be anywhere from maybe 85 to 110 days.


Participant Comment:

A friend of mine once told me that the way you know they're ready to be harvested is the tops just all lay over flat. Yes, ma'am.


That is exactly correct. They'll start to lay over like this. I'm going to move this out of the way.


I think we have some extras. They'll be kind of a little floppy. They look like they need water, but they don't.


They're ready.


Participant Question:

Well, they should turn yellow, right? I think they turn a yellowish-brown just prior to anything else. So when you're putting them close together, if you want to do green onions and stuff, those will be in about 30 days?


Yeah, like 30 days.


Participant Question:

Can you keep on just like instead of pulling it out, could you keep on cutting them and just still use the green tops for green onions and those will keep on going, sprouting?


I don't know about that. I really don't. I'm afraid if you just cut off the green part that it's not going to get any nutrients to the onion itself. It'll just stop producing.


Participant Question:

What if you just trimmed across?


You could probably just trim just like you do basil kind of. You know, you just take a little bit at a time.


You could probably do that. Now, if you let these get a little bigger, you're going to have like a scallion. And we have some over there that you can grow to a scallion size.


And that is something I will mention too. When you plant these and you see something that we didn't talk about, please don't hesitate to take a picture of it and bring it in. We have everything that you will need to care for to get you growing again.


Participant Question:

I'm a big fan of companion plants for everything I do. Is there any ones that work best with onions that you would recommend to grow with onions?


As far as fruits or vegetables?


Yeah, anything across the board.


I would recommend herbs. Herbs would do really well with your onions, your thyme, your basil. Or you could do even flowers. You could plant marigolds.


Participant Comment:

Marigolds are in every pot that I bring outside. For sure, for everything. Just to get out those worms. Or whatever those things are. It's good for the bees as well.


Yeah, they do. They love it. You really don't have to worry about too many pests. Because they're not really going to go to it. And I would recommend planting garlic with your onions as well. Because there is nothing that will go to garlic. So your squirrels, your rabbits, all of those little critters won't go near your onions and garlic.


Participant Question:

Can you dust around the garlic as well? Will the sulfur not have any residual effect on the garlic? Like they don't have any things with the onions with the sulfur dusting?


I don't think so. I think you can use sulfur for all your wettables.


Participant Question:

How many onions would you put in a pot?


I wouldn't put more than maybe four or five. When you start to see some of them getting bigger than the others, I would pull the ones that are not producing and use as your green onion. Yeah, your green onion. Or a scallion, depending on the size that it's growing up to.


Participant Question:

Will the frost kill it?


They shouldn't, but I recommend covering. It's going to be a cold freeze. I covered my garlic just for those two days. And then I uncovered them and they were fine.


How much fertilizer would you put with those?


You want to just follow the instructions on the bag per one gallon. And you would just, I mean you don't have to like, at least you can. You're welcome. And just like a tablespoon per of the solution. I wouldn't put a lot, lot on, but you'll want to mix up the gallon and then just kind of do it along the edge of the plant or around, not on the plant.


Thank you. Thank you guys.



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