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Seedlings germinate and then die

Posted by dimitrig SoCal z10a/21 (My Page) on
Sun, Feb 26, 12 at 0:25

I use a seed tray to germinate seeds, but my success isn't that great. I have a pretty good rate of germination, but the seedlings often die shortly after.

This latest effort I planted spinach, kale, chard, parsley, and parsnips. They all germinated, but within a week they started to yellow. I was fearful that it was fungus/rot so I removed the cover from the tray (I had it covered to retain moisture) to let some air circulate.

This seemed to make things worse. As it is, there are still seedlings that have survived, but compared to the number of plants that germinated it is maybe just 10%.

So where am I going wrong here?


Follow-Up Postings:

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RE: Seedlings germinate and then die

We really can't say what you might be doing wrong without knowing more about what you are doing, period.

Damping off diseases are usually caused by a combination of overly moist potting mix, poorly drained containers, lack of good air circulation, temperatures too high, and more.

Tell us a little bit about your 'set-up' and techniques so we can help you trouble shoot the problem. Once the seeds have germinated, you should have 100% success rate with the seedlings.


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RE: Seedlings germinate and then die

Ok.

I am using a seedling tray with a clear plastic cover. I water once and never water again unless the soil dries out entirely, which is not often. I might water once per week.

One problem I am having is knowing when to remove the cover. After germination, I leave the plastic cover on to keep the soil moist. If I take it off, the soil dries out quickly. However, if I leave it on the seedlings don't receive that much light because the plastic cover is covered in condensation and the soil stays really moist.

The seedlings seem okay and then gradually yellow, eventually shrinking and disintegrating completely. This happens in the span of maybe a week. The soil I am using is seedling starter, so it should be sterile. It looks like peat or similar.

I grew columbine and hollyhocks in this manner and almost all seedlings survived. Pansies and veggies germinate and then die. I have tried a few times now.


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Also

The tray is outside in full sun, FWIW.

It seems a delicate line between "too moist" and "too dry".

Also, I am not sure how much sunlight the seedlings should be exposed to. With the cover on, not that much light makes it inside because there is so much condensation, but when I take it off the soil dries out very quickly in the 80 degree temperatures we have been having.


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RE: Seedlings germinate and then die

"I was fearful that it was fungus/rot so I removed the cover from the tray"

I suspect you were correct, removing the cover just came too late.

From everything I've read, the instant the seedling emerge, get rid of that doom or you risk damping off and maybe other problems due to the high humidity.

Also, if you have them out in the sunshine with the lid on I'd think you'd cook them? You would here anyway.

Personally, being in 10A, I'd skip the trays and directly sow them in the garden but that's just me.

I'm very much a novice though, so may very well be wrong. Just something to think about while waiting on an answer from someone more experienced.


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RE: Seedlings germinate and then die

I agree. Once the seedlings germinate, the cover becomes a liability. It reduces air circulation, keeps the medium too wet, and outside, just cooks the plants. Every drop of condensation becomes a lens that focuses heat on your plants. At those temperatures, with those crops, in that zone, you shouldn't be using a tray or cover at all, you should be direct seeding them in the ground where they will be grown. You're making it more complicated than it needs to be. Try some warm weather crops in a tray with a cover, and as soon as you see some green, take it off and start judiciously bottom watering. You'll have some great seedlings.


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RE: Seedlings germinate and then die

I also agree with the "ditch the cover soon as they sprout" advice. You're in zone 10, with a cover on them, and moist. At best you're creating a sauna. At worse, you are actively steaming your veggies a little on the early side (most people wait until they're big enough to eat =P ).


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RE: Seedlings germinate and then die

Our days are so warm that I'd suggest direct sowing, if possible. No need for the tops after germination is you do use trays, the yellowing sounds like over-watering.

I'm germinating tomatoes outdoors right now w/o any sort of covers and getting far higher than 10% germination rates.


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RE: Seedlings germinate and then die

Thanks dicot.

I, too get very high germination rates. It's survival two weeks beyond that which is the issue.

I will try removing the cover as soon as the seeds germinate.


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RE: Seedlings germinate and then die

I replanted and removed the cover after germination. This resulted in a much higher success rate. However, the problem now is that the seedlings grow so slowly. For example, chard is supposed to be 60 days to harvest, but it has been since March and it is maybe 5 inches tall. I fertilize with fish emulsion every 10 days or so. Plants look good, but *tiny*. Kale is even smaller.


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