Monday, January 10, 2011

Gardening: Growing Onions from Seed

Okay, who am I kidding? I couldn't wait. I'm probably too early to plant these onion seeds but I was itching to do something in the garden! I've never planted onion seeds before. The ironic thing is that I don't even like onions. Well, raw onions at least. I pick them off my food. I do like the flavor they bring when cooked though and I use them a lot. I know, my life is an oxymoron!

I've researched online and can only tell you that I was very confused. I asked advice from gardeners with experience and now think I am less confused. Who would have thought that growing onions really is a science?

I planted some Walla Walla Onion seeds yesterday (1/9/10). It's about 14 weeks before my last spring frost. I realize I maybe early but I thought I would plant another set in about 2 weeks to determine which did better. I've heard anywhere from Jan 15th to Feb 1st as ideal. Call it an experiment.

The temperature in the garage is 53 degrees (bottom right hand of the clock). I didn't use a grow mat because upon more research, onion seeds germinate 97% at this temperature, but just takes longer. Optimal temperatures are 50-60 degrees F. If they don't spout in a week, I'll add a heat mat to the bottom of the trays. I am using grow lights to help the seedlings along.

In my research on how to grow onions from seed, I gathered a lot of good information from various sources. I've included them here for future reference. If you have additional information, I'm all ears! Here's what I've gathered thus far:

Use fresh onion seeds!! Seeds for onions are usually only viable for 1 year. If you've had them for longer, do a viability test to see what your rate of germination is.

Different types:
Onions come in different sizes, shapes, color, flavor and storage life. Pick one that suites you. Sweet onions (my preference) do not store well.

- Long-day varieties: These need 14-16 hours of daylight to form bulbs and are best for regions in the Northern latitudes (ie: Canada, Alaska & the Pacific NW). These are generally planted in early spring and form bulbs as the days get longer in the summer.
- Intermediate-day varieties: These require 12-14 hours of daylight and are best for regions such as the San Francisco Bay Area and northern Nevada.
- Short-day varieties: These need 10-12 hours of daylight and are best in areas in the southern latitudes.
- Day neutral varieties: These are hybrid onions that bulb up anywhere and does not rely on sunlight hours. The yellow "Candy" onion and the white "Super Star" onion are some day neutral onions.

When to Plant Seeds:
- Spring planted/Fall Harvest - For fall harvests, you have to seed onions 10-12 weeks before your last spring frost date. You plant them out about 4-6 weeks before your frost date and harvest in late summer or early fall.
- Fall planted/Summer Harvest - You can also seed them around August/Sept to set out to overwinter. These will be ready by July.

- As you seedlings grow, some people have suggested to give them haircuts to keep the green sprouts to 3-6 inches long.

- Plant your seedlings or starters about 4-6 inches apart (see individual seed packets for optimal planting distance). Weed your onion patch regularly and fertilize. If your onions bolt (produce flower), try cutting off the flower.

Bulbing up:
- Onions produce bigger bulbs with more leaves on the plant. The earlier you are able to set out your seedlings, the better. I've also heard that thinner plants (no bigger than a pencil) do best at planting. Onion plants are able to handle a little frost (no hard freezes). Around summer solstice (late June), onions will no longer produce leaves and will start to "bulb up". The more leaves they have at this point, the larger your bulbs will be. To encourage top growth, be sure to fertilize onions regularly (esp. early in the growing season) with low nitrogen complete fertilizers (for bulbing onions only).

- When the onion leaves start to turn yellow and collapse (around late summer), your onions are ready to harvest. Stop watering onions once they start to lay over. Lift bulbs gently out of the soil to harvest them.

- If you plant on storing your onions, you must dry them thoroughly or they will rot. To dry them, stack them in a single layer in slatted boxes or on newspaper in a warm, dry and well ventilated area. Be sure to allow air to circulate around the onions. When the necks of the onions are totally dry, they are "cured" (about 2 weeks).

Again, this is all information I have read or been given as advice from others. If you have any other advice or if the information is wrong, please leave a comment! Thanks!

- Seedlings planted 1/10/11 (Walla Walla)
Seedlings abandoned

- Seedlings planted 1/23/11 (Copra & Walla Walla)


Robin said...

I grew onions from seed last year for the first time. I have to say that it was a pain thinning them. My onion crop last year was a complete failure....the smallest I have ever grown! Hopefully your crop will do well for you.

~TastyTravels~ said...

Thanks Robin! Any tips for the rookie?

Melinda said...

I have never done well trying to grow onions - never! I always blamed it on our heavy clay soil - but I wonder if there's more to it?

~TastyTravels~ said...

Melinda, This is my first attempt so we'll see how well it goes. Hopefully I'll have something to set outside. If not, my back up plan is to buy sets. I'm not sure where I'll plant the onions. I have clay soil as well but my ammend it or make room in some of the raised beds I have or try container planting them (realizing this may less than optimal).

Malay-Kadazan girl said...

Good Luck with your onions. It is our first attempt too last spring growing from seeds. So we are waiting for them to grow. I find it confusing at first with so many varieties to pick but have to be cautious with the day-length thing.

Sue Garrett said...

We've always grown onions from onion sets other than spring onions which we have grown from seed.

Hope you have success

p3chandan said...

I love your post about onion because Im planting them by seeds too this year given by Malay-Kadazan girl all the way from Australia! At the moment Im planting them using onion bulbs solely for their leaves for garnishing, in soup, stir-fry, noodles etc. So hope to compare notes with you!

fer said...

I hope your onions grow great! I wanted to have some this year, but I missed the opportunity.
Thank you for joining us!

becky3086 said...

This was some very good information. I have never had any luck growing onions unless they were green onions. I guess I should have done more research but just planted the sets that the store offered. Will have to try a short day variety and see if that does better. I don't believe I have enough time to start them before my last frost but maybe.

Noel Morata said...


what a lot of onions to plants, good for you in getting a head start...i haven't even started and i live in hawaii :)

thanks for sharing that and showing us your garden today

Carolyn @ Carolyn's Shade Gardens said...

I planted onion sets a few years ago and mostly got tops. But I left them in the garden and they have continued to produce new shoots in the spring, which I use like scallions, and bigger stalks, which I use to make stock. I am in zone 6 so they have withstood more than a few hard frosts.

ann said...

Very good info on onions. ann

Rebecca said...

Love it! Only gardeners will understand planting something you don't like just because it's fun to see if you can grow it! Good luck on your project-keep us posted!

Eliza @ Appalachian Feet said...

Wonderful, thorough post on onion growing! I appreciate that you even have the info on onion day-length.

Eliza @ Appalachian Feet said...

This is great information! Last week I dumped all the old onion seed packets I had into the same tray to see if any of them germinated. If they do. I guess I will transplant them out later. I wish I'd read your post before I tried it!