Mold on seedlings

matcoApril 19, 2012

Hey everybody, I have the 36 set seed starter and my plants are sprouting great BUT.... some of them are starting to grow mold. I'm watering them as directed and I'm sure it's over watering but I just wanted to double check with the folks that aren't rooks like me. I tried to post a picture of the setup but I can't figure out how to do it

Thank you for reporting this comment. Undo

Mold = damping off.

1) too much moisture & 2) not enough air flow.

Scrape off what you can and dispose of it.

Cut back on watering, only water when they look like they really need it. Bottom water if you can.

If you have an oscillating fan, put it on low and place it far enough away from the plants so they just get a gentle breeze over the stem/soil area.

If the seedlings aren't falling over now, you can save them.


    Bookmark   April 19, 2012 at 8:27PM
Thank you for reporting this comment. Undo

Sorry, I should have asked, is the mold white or green?

If a white powdery mildew/mold then it's damping off. It attacks roots and stems.

If it's green, it'll rob the oxygen from the soil/starting mix and choke the roots.

Both bad but both have the same solution I referenced in my previous post.

    Bookmark   April 19, 2012 at 8:42PM
Thank you for reporting this comment. Undo

Nah they're not curling at all look really healthy, I got the window open in the room most of the time with a ceiling fan going and it's being watered from underneath with the kit provided. I only water when the soil looks dry, should I hold off on that from now on?

    Bookmark   April 19, 2012 at 9:00PM
Thank you for reporting this comment. Undo

Go to Walmart (or any other place with a pharmacy) and pick up some hydrogen peroxide, 3% strength. Its normally sold as a topical antiseptic in a brown plastic bottle. Sometimes you can find it already in a spray bottle, if you can't, get a spray bottle while you're there.

Spray the 3% H2O2 directly onto the mold and the seedling. Repeat daily as needed.

3% isn't strong enough to hurt a plant, not even a seedling (takes about 10% to do that), but it will kill mold and fungi fairly readily.

    Bookmark   April 19, 2012 at 9:14PM
Thank you for reporting this comment. Undo

+1 on hydrogen peroxide

    Bookmark   April 20, 2012 at 8:30AM
Thank you for reporting this comment. Undo

If its those fiber molded trays you have them in, I would transfer the seedlings to cups or pots rights now because mold loves to grow on those trays.

    Bookmark   April 20, 2012 at 7:48PM
Thank you for reporting this comment. Undo

Edymnion beat me to the Hydrogen peroxide recommendation. Hydrogen peroxide will help to kill off the mold and it also is great for soil drenches if you think you might have some root rot because it kills the mould or bacteria thats causing the issue and it decomposes into water and oxygen.

The oxygen alone will help the root system stay healthy or recover from a sickness. I also use it in hydroponics once a week in small amounts. You can also pick up 30% from a hydroponics store and dilute it down.

On the down side since your growing in soil only use it when you have to because it kills everything from bad to beneficial bacteria and fungus. Definitely give it a try.

    Bookmark   April 21, 2012 at 8:22PM
Thank you for reporting this comment. Undo
esox07 (4b)

Hydro Peroxide will keep the fungus gnats at bay too.

    Bookmark   April 22, 2012 at 1:08AM
Thank you for reporting this comment. Undo

JMoore, slight correction there. You've got the right basic idea, but the wrong line of reasoning. Root rot is not caused by mold or anything like that, the mold is the results.

Most people don't realize it, but plants require oxygen to survive just like everything else. Its true that they use CO2 and sunlight in photosynthesis to make food, but they use basically the same kreb's cycle that we do to turn that food back into energy, and that means they have to burn oxygen to do it.

Up top in the leaves, thats no problem. The leaves produce more oxygen than they use so they're fine. Its down in the roots that it becomes an issue. If you overwater, you literally drown the roots because they can't get enough oxygen. The roots die, then they start to decompose, and thats where the mold/rot/etc you see as root rot comes into play. It didn't cause the root death, it just moves in after the fact.

One reason the H2O2 helps prevent root rot is because like you said, it rapidly decays into water and free oxygen, which helps to oxygenate the roots, which prevents the plant from drowning.

Now you know, and knowing is half the battle, YO JOE! =P

    Bookmark   April 23, 2012 at 11:33AM
Thank you for reporting this comment. Undo
esox07 (4b)

Another thing when you water with a H2O2 mix. It makes the soil "puff up". I used it to sucessfully battle some fungus gnats and the soil puffed way up and as it dried, stayed that way. I am sure it enabled a lot more air (oxygen) to reach the root system. Soil tends to compact after a while, the bubbling action of the H2O2 helps with that.

    Bookmark   April 23, 2012 at 12:24PM
Thank you for reporting this comment. Undo

It also helps to break up or "till" the crust on the top portion of the soil. Make it especially airy on the top half inch or so. This helps prevent damp off. I use a sharpened chop stick to do this. Many people have a habit if pressing down or compacting the soil around the base of the plant. That's the opposite of what you should do.

    Bookmark   April 23, 2012 at 3:53PM
Thank you for reporting this comment. Undo

The remedy I use for this situation is the following. Hold off on watering, put a fan in the room to circulate the air. A few sprays to the soil of chamomile tea in a spray bottle. This has gotten rid of mold on my seedlings in the past. This year, I'm using organic coconut fiber as a seed starting medium and it has stayed moist but not moldy, as peat can often get(so far).

Here is a link that might be useful: Check out my chile pepper blog for recipes, tips and gardening info.

    Bookmark   April 23, 2012 at 9:26PM
Thank you for reporting this comment. Undo

How do you get air flow when you are using those per packaged green house, I have the same mold problem as explained.

    Bookmark   March 5, 2013 at 8:47PM
Thank you for reporting this comment. Undo
esox07 (4b)

ImperialArm: are you asking how to get air flow in a green house? A simply fan will suffice I would think. Get one with a thermostatically controlled heating element and it will keep a nice air flow going. In a large green house, you would need a bigger fan, in the smaller ones like the one pictured below, the fan pictured would be more than enough. Just place the fan on the bottom tier and the heat will rise when it kicks on. The fan part will keep the air moving. You can buy these heater-fans in most stores, walmart, home depot, etc....

Here is a link that might be useful: Heater fan on

    Bookmark   March 5, 2013 at 9:07PM
Thank you for reporting this comment. Undo
DMForcier(8 DFW)

He may be talking about the domed starter trays.

For those, take the lid off and run a fan for a few hours a day.

    Bookmark   March 6, 2013 at 3:03PM
Thank you for reporting this comment. Undo
esox07 (4b)


    Bookmark   March 6, 2013 at 4:02PM
Sign Up to comment
More Discussions
Pepper Received in Trade - Yellow Beddin???
Does anyone know of a pepper named Yellow Beddin or...
Help! Overwintered Ghost Peppers Dying
Overwintered Ghost Peppers were doing fine all winter...
best flavored of the "super hots"
I am sort of reluctant to use the words "super...
Hate the new layout
How about you? Usually, I don't care, but this blows. Kevin...
Sponsored Products
Glove Leather Lounge Chair in Black
$899.00 | LexMod
Offi | Overlap Tray
$179.00 | YLighting
Recife Checkered Field Grey/ White Rug (7'6 x 10'9)
Thomas Lighting Posts Covington 1-Light Outdoor Painted Bronze Post Lantern
$53.00 | Home Depot
Brella Mocha Bronze Mini Pendant
$207.00 | Bellacor
Solid Shag Runner by Chilewich
$150.00 | Lumens
Trademark Global 14 in. Arizona State University Neon Wall Clock LRG1400-ASU
$59.99 | Home Depot
Slumber Solutions Gel Memory Foam 12-inch Queen-size Mattress
People viewed this after searching for:
© 2015 Houzz Inc. Houzz® The new way to design your home™