30 Second Guide to Growing Onions

Posted January 30, 2017 by Lauren Dibble in Gardening / 1 Comment

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how to grow onion plants from sets

In this series I’m compiling the quick and dirty info on growing specific vegetables. Just the basics. No fluff, no frills. When you’re sitting down in the late Winter, surrounded by seed catalogs, and your garden plan in front of you, you want a quick reference. How far apart can you plant? What pH do they need? How much water? What vegetables can you plant next to others? Which should you avoid?


Onions are a staple in any American kitchen. I have fond memories of my grandmother’s kitchen. The smell of onion skin, garlic, and banana nut bread still bring me back to playing on the kitchen floor while she cooked.

While I’m sure she wasn’t aware, the health benefits of onions are amazing. High in biotin, manganese, vitamin B6, copper, vitamin C, and many other phytonutrients, they are a sulfur containing food. If you’ve read my blog at all, you’ll know I’m a follower of Dr Terry Wahls and her TED talk on “Mind your mitochondria”. Her story is amazing, if you haven’t watched it already.


In addition to the vitamins and minerals above, their phytonutrients have said to reduce the risk of some cancers, reduce the risk of heart attacks and strokes, and reduce cholesterol.

Medicinal Properties of Onions

In addition to promoting good health, onions can be used medicinally – as a kitchen remedy. Onion juice has been applied to the skin for centuries to prevent bacterial and fungal infections. It can be used to remove warts, stimulate hair growth, and reduce unwanted blemishes. Warm onion juice can also be dropped into the ear to treat an ear ache and a poultice made from baked onion can be used to draw pus from abscesses.

While the folk remedies have been used for centuries, modern research is beginning to support the medicinal properties of onions.

how to grow onion plants sets from seed use onions medicinally remedy

They are also incredibly easy to grow, needing only occasional weeding. They can be started from seed or you can buy onion “sets” or small, already started onions.

Starting onions from seed gives you the opportunity to grow more varieties of onions, whereas the “sets” you can generally find in feed stores are hybrids. To start them from seed, dig a shallow trench (1/4 inch deep) and sow them in a long line. Keep them warm and moist (but not soggy!). It may take a few weeks for them to sprout. Be patient! Once they’ve begun to sprout and grow tall enough to fall over, cut them back a few inches. These onion sprout trimmings are a great addition to soups, salads and sandwiches.

Once the root balls are about quarter sized, you can harden them off and transplant them outside. Check out my post on how to start plants from seed for tips on transplanting success.

If starting the onions from “sets“, plant them in bunches of four. The onions will grow away from each other, but be easier to water and weed.

If you grow onions this year, check out two different onion soup recipes I have:

how to grow onions onion sets onion plants

Soil pH



3+ hours


1 in per week

Planting Time

Direct sow “sets” as soon as soil can be worked. Start seeds Jan-Mar.

Compatible With

Beets, Strawberries, Tomatoes, Lettuce, Chamomile, Roses

For a complete list to companion plants check out my Long List of Companion Plants.

Avoid Planting With

Beans, Peas


4 inches


Weed and mulch.

Harvesting Fruit

When stalks turn yellow and fall over.

Saving The Seeds

To harvest onion seeds, you need to leave the plant in the ground for two years. Onions only go to seed every two years. The plant will form flowers and then seed heads. Once the flower starts to dry, harvest it and dry it out completely. Then separate the seed from the rest of the flower.

how to grow onion plants from sets

One response to “30 Second Guide to Growing Onions

  1. One problem I have with growing onions from sets in onion maggots. I have to pull my onions by early July or they get riddled. I’ve tried using wood ash, but it hasn’t been that successful in keeping them away from the bulbs. Last year I tried diatomaceous earth and had a better result. Even so, I have enough onions to dry and save for winter from my small raised bed garden. – Margy

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