I have about 800 tomatoes under lights right now. I started them a couple of weeks ago. I have had constant yellow, white and green mold growing on the peat pots themselves. There is some green mold growing on the top of a few(30) that stayed damp longer for one reason or another.

I currently water only a couple of drops per day and never directly on the plant. I have not had one die that has mold directly on the top. I put a thin layer of sand on top once I noticed the mold.

I don't think mold is as big a problem as we make it out to be sometimes.

It is completely possible to grow seedlings straight through the white fuzz without any problems. But ... it is a warning to you that conditions are suitable for fungi and that might lead to damping off.

Damping off refers to a range of "diseases" that cause the stem of a plant to collapse at the base, but it certainly is caused by a fungus (several different fungi in fact).

Damping off occurs when small plants are too wet, either soil or humidity (I have had seedlings damp off in very dry soil, OK it was a Pediocactus, but still it was caused by humidity), wrong temperature (might be too warm or too cold), and most of all by stagnant air. Try to let plants cool off by 10F or even 20F at night, don't keep the soil saturated, let the humidity drop once germination has started, and keep the air moving. Seedlings don't damp off outside, too much air movement and cooler at night.

For what its worth, the yellow and white discolouration of the soil is likely to be a lichen and the green most probably algae. You can recognise lichen as it tends to colonise the driest tips of the soil surface first as it dries, making the soil appear speckled. The green algae means the soil really is too wet, it is easy to stop with moving air because it will dry out and die. Or you can sprinkle sand on the surface and that puts a stop to it, provided you don't keep overwatering.

Is fungus bad? No, fungus is fungus. Fungus is "fashionable" at the moment and the eco-freaks like to talk about all the beneficial fungi, but some of them are harmful to plants. Fungi are most often seen living off dead organic matter, but their hyphae can be extremely destructive to living matter too. It is fungi (and sometimes bacteria too) that turn dead plants into soil (humus) and also turn rock into clay.

Diane, first I admire that you called them and got a refund, way to go.

Second, I started my seeds in the GH back in January. Since then I've gone through troubles with vent openers and too much humidity yada, yada....in fact it stayed so moist in there at one point there was mold growing on the peat pots (as another poster mentioned)...despite this, I still have seedlings that are doing well. I treated them with a fungicide which seemed to help a bit, but in retrospect if I have to do it again I will use Hydrogen Peroxide. My point is, I was pretty sure all of mine were goners...but nope...they made it. Mold and all.

Don't give up.

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I definitely recommend the hydrogen peroxide. It got rid of the white fuzz and gave my seedlings a much healthier appearance. I continue to use it every 3 days for maintenance even though there is no more mold. 1 part H2O2: 20 parts water.

If your plantlets aren't keeling over and dying, you haven't got damp-off. This is good.

Every year I start plants from seed, every year I get white fuzz and green algae-looking stuff. Every year I fret and wonder what it takes to avoid these plagues. Every year, most of my seedlings to make it into the garden.

You've done all the right things: take off the plastic lids and leave them off - their job is done. Spritz with a little fungicide or peroxide (or not - I get about the same results either way). Let the soil dry out a bit. Let your ventilation be as good as you can manage, given your space constraints and the weather. The white stuff will go away. The green stuff will probably remain until you pot the seedlings up into a different container with fresh soil.

Thank you all for your responses - they're very encouraging. I know there are countless varieties of fungi out there, that many of them are beneficial, and I'd read somewhere the list of 4-6 specific ones that cause damping-off ... I just jumped to conclusions and figured with my luck, I probably had one of those.

The flats are in the house - only 3 seeds have sprouted so far, but I expect the rest won't be far behind. Once they're all up, I'd like to move them out to the greenhouse, which is kept around 50 degrees at night, and about 65-70 on a sunny day - though it would easily climb higher if I let it. I was thinking the best time for this is when they have their first set of true leaves. Any suggestions?

I tried starting seeds indoors years ago, with little success. This year, with the greenhouse, I thought I'd have a go at it again because of the lower cost, greater variety available, greater satisfaction of growing from seed ... and, despite the wonderful flowers, herbs and a few veggies growing out in the greenhouse, I just can't wait for spring!

It's good to hear of your respective successes, and to see the pictures you posted.

Diane, wishing you continued success.

I like the temperatures in your greenhouse. Just make sure it doesn't drop below 50F at night. Most people keep their seedlings way too warm at night. Then most people complain about how leggy their seedlings are ;)

Diane,

Damping-off of Seedlings is caused by a variety of fungi, but apparently not by the white fungi you saw, or your plants would most likely be dead by now. I think one possible mistake you may have made was in not removing the clear dome covers as soon as your seedlings emerged. I rarely leave the covers on for more than a few hours after the seedlings emerge.

I also use small fans to provide an artificial breeze for my seedlings. The "exercize" provided by the fans makes for stockier seedlings with thicker, stronger stems. That air circulation also dries the surface of the growing medium. I prefer not to use organic fungicides, and particularly not any that contain toxic metals.

Excessive green algae can compete strongly for available nutrients and stunt your seedlings, but simple "cultivation" of the surface of the growing medium with something like a toothpick, combined with the drying action of the fans, can go a long way toward controlling algae growth. And I have had success with hydrogen peroxide as well.

MM

Again, my thanks for continued replies. Please note, however the following excerpt from my original post:

"A few seeds are just beginning to break the surface."

Four out of 72 seeds sown were beginning to be visible ... on the third day after sowing. It hardly seems the domes were left on too long ... as a matter of fact, I don't know what these seeds are doing up so early! The broccoli was the first to emerge, followed by lupine, now joined by tomato, bush bean and chard, for a total of 9 sprouts. The majority of seeds have not yet germinated, but the domes remain off, and I continue to mist as necessary to maintain moisture, using chamomile tea. Most of the white fuzz has disappeared. I've not seen any algae at any point.

I had read about "exercising" the seedlings by "petting" them or providing a breeze, and will provide that component as soon as more seedlings have emerged.

Di

Hi all,
so encouraging to read that i am not the only one with moldy peat pots!! this is the first year i have done this so am suffering from newbie problems. I now know that i had the peat pots too close together.
i was worried about all the mold and did repot 4 of them. they are now spread out and i am allowing them to dry out a bit. I also rubbed the outside of the pots with lemon juice. That helped a bit but still have mold on some of the pots.
so far all my plants (70+) are doing well.
i like the idea of the fan to strengthen the stems.
i am wondering if the hydrogen peroxide is considered an "organic" treatment?
Sherry

I think with the temps in your greenhouse, I would have done the whole process there.

I grow everything outside, starting them on my porch, and moving them to a sunnier location soon after they germinate. I never have to worry with hardening them off, and my biggest problem is getting them pricked out and repotted in a timely manner!

I know all mine germinated in less that 50 degree nighttime temps.

Good luck!

Janie

Sherry, I might have panicked a little early, since the fungus may have been benign, after all, and never returned after I started misting with the chamomile tea and increased air circulation. Probably something many of us newbies go through. Glad to hear you've got your situation under control also.

Janie, I'm glad to hear you get good germination in 50 degrees; I expect the soil temperature is higher from daytime sunlight. Might give it a try and compare results, since I've noticed the soil in the GH warms up quite nicely during the day. Current set up is to start them on a rack indoors, then cycle them out to the GH when they've sprouted, making room to start another few trays indoors. Also have several wintersown containers sitting outside and more to go; it's a nice easy method, but nothing has sprouted yet and I needed to see that process begin :-)

Di

I've also read in the hot pepper forum about using chamomile tea to prevent damping off.