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How to Grow Organic Onions

Written by – Kaitlynn from MIgardener

In preparation for the cold season, let’s look forward to spring! It seems a long way away now, but late autumn is the perfect time of the year to start brainstorming for your spring garden. Continuing on our growing guide blog series, today, we are going to focus on how to grow organic onions. In our seed starting guide and Clyde’s garden planner, we map out the recommended time frame for starting onions indoors. We highly recommend doing this for the best results from your onions.

Let’s get started. Before you start your onions, it’s essential to find out what types you need for your area. Onions come in either long, short, or intermediate day varieties. If you are north of the 37 latitude mark on the map, long-day varieties are the best choice. Short-day onions are best in the south. If you find yourself somewhere in the middle, intermediate day varieties will be the most successful.


Onions prefer loose soil to allow their spindly roots to establish properly. Adding worm castings and compost to the soil will help create a perfect base. The onion bulbs themselves are not the roots but are fully matured stems. It’s important to fertilize in a way that promotes leaf growth, which will allow the bulbs to form. Fertilizing with a nitrogen-rich fertilizer like Trifecta+ is the best way to achieve this.

organic onions

Tip: to grow HUGE organic onions, prune the leaves of each plant as they crimp and fall over. Regular pruning will help add energy to the growing process and extend the growing season.

Ph Level:

Slightly acidic soil is recommended (5.5-6.5) for the best flavor.


Onions require full sun. The exact times will depend on whether you are planting long or short-day varieties, so pay attention to that when it comes. Depending on the variety, some onions are


Onions require consistent supplies of water, so either irrigate the onion patch or follow the methods of core gardening for a hands-off approach. Maintaining even soil moisture should be the goal. Learn more about core gardening here. Provide extra water towards the end of the season until tops fall over for harvesting. At this point, they will be dripping with flavor and ready to store.


Give onions enough space (4-6 inches apart) for them to reach an impressive weight. For high-intensity planting, 4″ will be the ideal amount apart for each plant. Using high-intensity spacing methods will also cut down on the amount of weeding you will have to do in the garden. Make sure to weed around your onions as much as possible.

organic onions



For winter storage, allow onions to fall over naturally. If you need to harvest sooner, knock the tops down and leave the bulbs in the ground for 1-2 weeks to develop thick skins. Harvest when the majority of leaves are dry. Find a sunny place to let them sit for 3-7 days before storing them. Store in a shady, warm, dry place. Enjoy your exceptionally flavorful organically grown onions!

organic onions


This grow guide is based on videos from our youtube! Find more information about MIgardener on Instagram, Facebook, or on our website at MIgardener.com. 

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