Today’s project – Sowing onion seeds

Starting Seeds

Today I planted onions, leeks, shallots, and bunching onions.

I really think they are my favorite vegetable family to grow. They are the seeds that are planted FIRST – right after Valentine’s Day and right in the middle of the coldest and snowiest part of winter. It’s just so exciting to plant and know that now there’s a part of spring growing and on its way.

Onions are very happy grown close together. I worked at a farm that planted their onions in trays with a guide to space seeds exactly one centimeter apart. The seedlings grow up with perfect spacing until they are planted out in the field.

A guide board with a one centimeter array provides room for about 1,500 seeds in one 10 x 20 inch tray. I don’t plant an entire tray with one type of onion. I’m planting one type in each 4 by 4 inch tray. It would be fun to make a guide for these trays someday.

I bought my 4 by 4 inch trays on-line at Greenhouse Mega Store, but I bet plastic recyclables would work as well. Each 4×4 tray hold about 100 onion seeds when set about 1 cm apart. I pour about 100 seeds into my palm and then I scatter them, doing my best to spread them out.

It’s very nice to have onion seeds that are coated with a white gelatin so they are visible against the soil. Another thing you can sometimes buy is coated seeds. These seeds end up big and white and round. They are meant for use in a mechanical planting machine, but is sure helps when manually planting too.

To prepare trays for sowing, I do the following:

1. Make sure all pots are new (nothing planted in them before) or have been disinfected.

2. I use soil without fertilizer, so I add a good handful of an organic fertilizer to a bowlful of soil and mix. Fill each planting pot half full with fertilized soil. Having the fertilized soil at the bottom of the pot puts it where the roots will be.

3. Add a handful of unfertilized soil to the top of each pot. Shake it to level it and make sure it it filled to the top of the pot.

4. Compress the soil in the pots gently with your fingers. It will go down about 1 cm. I plant the onion seeds on this surface.

5. Label each pot for the variety you will plant there. Pour about 100 seeds into your palm and then scatter them, doing your best to spread them out evenly.

6. Cover each planted pot with a thin layer of fine soil. Vermiculite works well. I used some of the dry fine potting soil I used for planting. Do not cover to thickly. A couple mm is fine.

7. Gently water the pots. I have a nice gentle sprayer on my kitchen sink and I like to use that. Make sure all pots are well wetted.

8. I usually leave leave the trays full of newly seeded pots near my kitchen sink to drain overnight. Then I move them to a location with plant lights and airflow. The optimum temperature for onion germination is 68 to 75 degrees F (20-25 degrees C).

To figure out how many onions you can plant in the garden space that you have, remember that onions like to be planted close to each other. Plant them 4 inches (one fist width) apart in both directions. A six-foot row will hold 18 onions (3 per foot). A 6 x 6 foot patch will grow 400 onions if you plant then in an alternating pattern in rows that are 3 inches apart.

Shallots and bunching onions (scallops) should be spaced the same as onions – 4 inches apart. Leeks should be given a little more space: 6 inches apart.


I recommend a great presentation by a professional vegetable grower about seed starting, contact Jen Boudrie (MA Department of Agriculture) <> and ask for the Zoom link for presentation by Hannah Traggis, Tuesday 7-8pm EST, February 16, 2021, FREE. Registration not required. Before 5pm 2/16, email to get the Zoom link. Host:  The Veg/Fruit Group. CE credit 1 hour for Mass Master Gardeners.

SEEDS: Seeds, Seedlings, Seed Saving, Seed Sharing

Even though it’s wintry, you can begin planning and planting in the warmth of your home!  Learn how to start your seeds indoors and outdoors, how to properly care for and handle a variety of young seedlings, and how to transplant them.  Whether you want a little or a lot of produce, it all starts with seed.

Q&A Email seed questions to in advance for Hannah or post a question during the presentation in Chat.

Hannah Traggis is co-founder of Aurelia’s Garden, a nonprofit farming organization growing food for food pantries; and a Plant Physiologist at Freed Seed Federation.  She was formerly a Massachusetts Horticultural Society senior horticulturist managing Mass Hort’s edible gardens at Elm Bank and overseeing the Seed to Table vegetable garden. Check out Hannah’s recently posted 75 seed sources.

Hope some of you can attend! This lecture will be recorded and available to view later if you can’t attend live!

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