56 starter pots grew grey mold overnight. Why and what to do now?

[TrippleDip]

Well this is something I haven't seen before. There are 56 pots in two covered seed starting trays and overnight they all grew grey mold.



When found they were sprayed with 1tbsp per liter of 3% hydrogen peroxide. That little bit of mold on the inside of the pot got missed because it was shaded by the pot edge, it was a lot greyer before it was sprayed with h2o2. There is no visible mold on the soil surfaces now.

Most importantly, what do I do now? Does this mean all the seeds are dead, or will they still germinate?

Less importantly, where did the mold come from?

• Is it just because they were covered and the humidity was too high?
• Is the soil bad (brand new bags)
• Is it because I didn't wash the trays (also new)

I really want to figure this out because I have 500L of soil already in planters. Should I try to sterilize it somehow or just not worry about it for established plants?

Also these seeds are mostly things like raspberries and hot peppers for the coming summer but I do have one pot plant in the same soil and it hasn't shown signs of mold (yet).

 

[TrippleDip]

Also post your mold stories if you want to.

This moldy dirt scares me because I had yellow moldy dirt before (never spread to peat for some reason, maybe to acidic?), and it took almost 2 years to eradicate. Just when you thought it was gone it would pop back up and spread to a bunch more plants.

 

[bernie344]

Well this is something I haven't seen before. There are 56 pots in two covered sees starting trays and overnight they all grew grey mold.

View attachment 4820518

When found they were sprayed with 1tbsp per liter of 3% hydrogen peroxide. That little bit of mold on the inside of the pot got missed because it was shaded by the pot edge, it was a lot greyer before it was sprayed with h2o2. There is no visible mold on the soil surfaces now.

More importantly, what do I do now? Does this mean all the seeds are dead, or will they still germinate?

Less importantly, where did the mold come from?

• Is it just because they were covered and the humidity was too high?
• Is the soil bad (brand new bags)
• Is it because I didn't wash the trays (also new)

I really want to figure this out because I have 500L of soil already in planters. Should I try to sterilize it somehow or just not worry about it for established plants?

Also these seeds are mostly things like raspberries snd hot peppers for the coming summer but I do have one pot plant in the same soil and it hasn't shown signs of mold (yet).

What medium is that?

 

[TrippleDip]

What medium is that?

Peat based. Miracle gro. The planters and pot plant have amendments but the starter pots are just the straight mix.

 

[bernie344]

Peat based. Miracle gro. The planters and pot plant have amendments but the starter pots are just the straight mix.

Hows your air circulation?

 

[TrippleDip]

Hows your air circulation?

The lids were on, so very little. Do you think it's just a case of mold is everywhere and the humidity was too high?

I usually don't use the lids and instead mist it a few times a day but it's really dry right now. Also do you think the seeds are still viable or I should just toss everything and start over?

 

[bernie344]

The lids were on, so very little. Do you think it's just a case of mold is everywhere and the humidity was too high?

I usually don't use the lids and instead mist it a few times a day but it's really dry right now. Also do you think the seeds are still viable or I should just toss everything and start over?

How about the room temp?
Give the seeds 7 days from planted, what hasnt come up throw it.
You really need to get to the bottom of the problem to avoid this happening agian.
Can you offer more details about your setup.

 

[TrippleDip]

Give the seeds 7 days from planted, what hasnt come up throw it.

You're right, may as well see if anything grows. Only something to gain by doing so.

Can you offer more details about your setup.

This is the problem, I changed everything and now have no clue what caused it.

• Usually plastic pots, now paper. but I"ve used paper pots a lot in the past, just not for seed starting.
• Usually large 96 well trays, now small 28 well trays
• The trays were brand new and unwashed
• Usually no cover but used one this time, have to as it's sub 25% humidity rn.
• First time using miracle grow, but it was on clearance at 175 per cubic yard, usually I use compost and bales of peat moss. miracle grow has to be cleaner than compost, but that could be it's own problem - not enough bacteria.

Temps

Oddly enough one was given a sunny but cold window, maybe 18-20 degrees air temp. The other was kept in the dark on top of a grow tent at about 33 degrees. They molded fairly equally.

I just don't want it to be bad soil, much easier to fix bad conditions. Here's a pic of the two trays, not much to see. They have plastic covers.


Edit: the trays are wet because I just misted them with plain water. The covers are off for now.

I wanted to do a trial to see if flyer or lettermail held up better over time. You can grow a pot plant from seed in newspaper for about two weeks before the roots grow through the sides, and I have had hot peppers in them for over a month. I want to see if I can keep them in paper for four months until planting by moving from small to larger paper pots.

 

[hotrodharley]

The mold is from your room air. The spores that started it were that is. Once covered with high humidity it caused the spores to bloom. It should have a limited life cycle. Raise the covers a bit so air can circulate.

To make sourdough starter you mix 1 cup of flour and 1 cup of water. It can be tap water and you don’t have to dechlorinate. Leave it open to air in your kitchen a few hours. Cover with a clean dishcloth and place in a warm location. Stir daily. In a few days you will notice gas bubbles starting to form. Soon it will really start to grow and smell damned good.

Anyway that’s all that’s happened. Don’t sweat it.

 

[bernie344]

You're right, may as well see if anything grows. Only something to gain by doing so.




This is the problem, I changed everything and now have no clue what caused it.

• Usually plastic pots, now paper. but I"ve used paper pots a lot in the past, just not for seed starting.
• Usually large 96 well trays, now small 28 well trays
• The trays were brand new and unwashed
• Usually no cover but used one this time, have to as it's sub 25% humidity rn.
• First time using miracle grow, but it was on clearance at 175 per cubic yard, usually I use compost and bales of peat moss. miracle grow has to be cleaner than compost, but that could be it's own problem - not enough bacteria.

Oddly enough one was given a sunny but cold window, maybe 18-20 degrees air temp. The other was kept in the dark on top of a grow tent at about 33 degrees. They molded fairly equally.

I just don't want it to be bad soil, much easier to fix bad conditions. Here's a pic of the two trays, not much to see. They have plastic covers.

View attachment 4820605
Edit: the trays are wet because I just misted them with plain water. The covers are off for now.

I wanted to do a trial to see if flyer or lettermail held up better over time. You can grow a pot plant from seed in newspaper for about two weeks before the roots grow through the sides, and I have had hot peppers in them for over a month. I want to see if I can keep them in paper for four months until planting by moving from small to larger paper pots.

You could try a couple of heat matts under them to keep the temps constant, what happens when its lights out? Big drop in Temps?
But if the major change has been your soil then I would be leaning in that direction.

 

[Rdubz]

Well this is something I haven't seen before. There are 56 pots in two covered seed starting trays and overnight they all grew grey mold.

View attachment 4820518

When found they were sprayed with 1tbsp per liter of 3% hydrogen peroxide. That little bit of mold on the inside of the pot got missed because it was shaded by the pot edge, it was a lot greyer before it was sprayed with h2o2. There is no visible mold on the soil surfaces now.

Most importantly, what do I do now? Does this mean all the seeds are dead, or will they still germinate?

Less importantly, where did the mold come from?

• Is it just because they were covered and the humidity was too high?
• Is the soil bad (brand new bags)
• Is it because I didn't wash the trays (also new)

I really want to figure this out because I have 500L of soil already in planters. Should I try to sterilize it somehow or just not worry about it for established plants?

Also these seeds are mostly things like raspberries and hot peppers for the coming summer but I do have one pot plant in the same soil and it hasn't shown signs of mold (yet).

your soil looks super soggy too much water not enough drainage you want water to flow in and right out no sogginess that’s most likely the reason for your mold it’s not bad soil or unwashed trays

 

[bernie344]

your soil looks super soggy too much water not enough drainage you want water to flow in and right out no sogginess that’s most likely the reason for your mold it’s not bad soil or unwashed trays

So are you saying its good soil but it holds too much water?

 

[Rdubz]

So are you saying its good soil but it holds too much water?

Yes

Edit: so I’m not saying it’s the best soil I believe any soil can be good with the right blend , is there enough wholes underneath is it sitting up to allow drain and not sitting in water? Things like that and adding a vermiculite or something mixed will definitely help that’s what I’m saying

 

[bernie344]

Yes

Your statement is a total contradiction because good soil doesnt not hold too much water thats a major part of what makes it good
Ive heard enough nonsense from you.
Goodbye

 

[Horselover fat]

Your statement is a total contradiction because good soil doesnt not hold too much water thats a major part of what makes it good
Ive heard enough nonsense from you.
Goodbye

So you are saying you can't overwater in soil?

 

[Kassiopeija]

Perhaps that MiracleGrow wasnt composted well enough, as it looks coarse and not finegrained like a good pottingmix should be...

this mold is from amending peat with cow dung pellets

it did kill all seeds I tried to sprout therein.

 

[hotrodharley]

So you are saying you can't overwater in soil?

That’s a ridiculous statement or claim.

 

[Horselover fat]

That’s a ridiculous statement or claim.

Yes, I would think so too.

 

[TrippleDip]

The mold is from your room air. The spores that started it were that is.

Anyway that’s all that’s happened. Don’t sweat it.

Ok, good to know. I put the lids back on after punching some holes in the top and sides.

Sourdough

I thought the yeast in sourdough, cider, and wine comes from the flour or apple/grape skins though?

your soil looks super soggy too much water not enough drainage you want water to flow in and right out no sogginess

Both pics were immediately after misting. The pots even have holes in them. Usually I bottom feed so there is standing water in the trays but this time even the trays were dry.

Perhaps that MiracleGrow wasnt composted well enough, as it looks coarse and not finegrained like a good pottingmix should be...

this mold is from amending peat with cow dung pellets

it did kill all seeds I tried to sprout therein.

Green mold, Yikes! Also not comforting : (

 

[bernie344]

So you are saying you can't overwater in soil?

No