Erratic onion germination

Sowed my onion seeds under lights 1/10. I got maybe 60% germination at best, and about a third of those seem to “runt out” - I start to emerge, but instead of sending out that first long see you leave, they kind of just get about an inch tall, then the tip dries up, and most of the time, those don’t ever really recover.

Any idea what causes that? The only thing I can think of is that the air is too dry.

The ones that did make it past that stage look great, but instead of the 80 plants I was hoping for, I only have about 40 from the original sowing.

I sowed a second round since I had seed left. So I’ll end up with the right number of plants, although about half of them will be somewhat behind the other set the time I transplant them.

I used freshly purchased seed packed for 2019.

1 Like

Onions are known for being poor at germinating -I think 60% is about typical. I don’t why the tips are dying. Damping off disease maybe?

I’m still waiting for mine to come up. Sown three days ago. I would just keep re seeding.

1 Like

The air is VERY dry - dewpoints around 20 at temps in the 60s…I doubt it’s damping off.

Are seeds fresh? They have to be last year seeds, they loose growing power very quickly unless you keep them in ideal conditions - refrigerated, then next year you may get like 70%, but this is as far as they can go.

1 Like

I’m grrowing two varieties, Candy and Expression, both Intermediate-Day varieties.

Candy has done well for me in years past.

Both varieties are affected some, but Expression is the worse of the two.

Here are some pics - you’ll see that a few plants look pretty good, but many of them have dried out tips, some of them even dry out before they fully emerge from the media.


The air is very dry. I have been misting them, so I suppose it could be damping off, and my media is extremely well drained, maybe too well-drained?

They are in my basement. Ambient temps run in the mid to upper 50s, but during the day when the light is actually on, there’s enough heat from the grow light that it reaches the mid-70s in the immediate vicinity underneath the lights.

If it is damping off, would Captan or Chlorothalonil work? Those are the two fungicides I currently have on hand, and I realize it won’t stop what is already started, but might prevent any future affect.

I don’t know if that is the reason, but I would put your pots on trays filled with gravel under the pots and fill the tray with water to just below the pot. That water in the gravel will keep them in an area of slightly higher humidity without them standing in water. When your lights are on the added heat will evaporate more of the water, hopefully keeping up the local humidity in the air. The wider the trays the more surface area so the better it will work.

1 Like

I don’t know what works to stop it, but in the future it will help to sterilize your growing medium, or at least start with new every year - and plant lots of seed!

I don’t know the answer, but I’ve had something like this happen, too. With mine, it seems like the leaf tips get stuck in the seed cases, especially when the air is too dry. Then when they finally come out, they’re all shriveled on the ends.
Mine seem to bounce back okay from it, and I haven’t had a problem with germination rate. I’ve been temped to keep a dome over them for awhile and see if they do better with high humidity.
Good luck!

Soğan Tohumla yetiştirilip küçük soğanlar elde edilir. Bu küçük soğanlar başka bir yere dikilir bir karış aralıklarla. Bölgelere göre değişen zamanlar da dikim olur. Benim yaşadığım yerde Ekim ayında küçük soğanlar dikilir. İlk baharda 20-25 cm boya ulaşırlar. Haziran Temmuz aylarında hasat edilir. Size daha iyi yardım edebilmek için resim yükleme şansınız varmı acaba?

I thought about a dome as well, but then I find that they actually get too hot, the grow light does produce just a tiny bit of a greenhouse effect, and seems to warm it up well into the 80s underneath. I feel thats probably too hot .

1 Like

Using Google Translates:

Onion Seeds are grown and small onions are obtained. These small bulbs are planted in another place at intervals. Times vary according to regions. I planted small onions in October where I live. In the first spring they reach 20-25 cm paint. It is harvested in June July. Do you have a chance to upload pictures to help you better?

Not sure if anyone mentioned this but you can increase your germination rate by not sowing the ‘dead’ seed. If you put your seed in a glass jar with water, you will find some sink (live seed) and some float (dead seed). Skim the dead ones and let the sinkers stay over night. Strain them and smear them on top of your media (I use the back of a spoon). Media should be soaky wet. Then I sift some dry media over the seeds through a sieve, or you could use vermiculite. These are seeds I collected last year.
The top layer looks thicker because there is a lot of chaff along with the dead seeds. I could have done this when I harvested the seeds and then only saved the live ones but that time of year is too busy, and doing it this way works fine.


So it begins.

I also have 36 spinach plants started. Here’s to a great 2019 growing season!


I also planted Pattersons on Feb. 3 and on a heat mat. The first sprout is now appearing on Feb. 8. I hear you about the black seed being hard to see.


Here are mine sown into a 200 cell tray. 100 cells of Alisa Craig Exhibition on the left and Cabernet F1 on the right.

Looks like 80+% germination, which I’m pretty happy with.


I think I figured out the issue. The mix I’m using must be contaminated, because almost everything I’m growing in that mix is showing some signs of damping off.

The other batch, which I started in a completely different media, seem to be fine.

1 Like

Sounds like you figured it out- good job.

I learned a lot following this thread. I quit starting my own years ago but stuff like this is making me want to start again. Just what I need!


1 Like

Oh, the unknown projects I have taken on due to this forum, planting things I had never even heard of, trying bizarre methods, etc.! This site is addictive.