All of my seedlings have been doing so well. I have transplanted many into 3 0r 4 inch pots. I also made some mistakes I've found. I put some of my pod seedlings into rectangular 10 cup peat pots. I put the long peat pods into the plastic trays. 5 across. Well now I see that many of them have a white moldy growth on outside of pots. I am sure I must have watered them too much as they are a mess. And they were doing so well!! I know I read somewhere about using peroxide solution but I need instructions. I have begun to take the seedlings out of those pots and put them in others but stopped because I wasn't sure what to do and I don't want to loose them.. If I knew how to attach pictures I would do so.
I'm not sure that mold can be "cured": most people talk about prevention. On the other hand, if the mold is only on the pots, and not on the stems, you might be lucky.
I have heard many people say they use peroxide stronger than this, but I've stayed on the "weak" side because I only use it for soaking seeds, not fighting fungus or mold. This site suggests 0.2% for sick or fungusy plants. Since you'll be spraying sides of peat pots, maybe you can go much stronger.
I assume you are starting with normal 3% "drugstore" peroxide (not the 35% food grade stuff).
1 cup water + 1 tablespoon of 3% HYDROGEN PEROXIDE
1 pint water + 2 tablespoons of 3% HYDROGEN PEROXIDE
1 quart water + 1/4 cup of 3% HYDROGEN PEROXIDE
1 gallon water + 1 cup of 3% HYDROGEN PEROXIDE
I agree with Rick, I use only plastic trays and plastic inserts. When the plants need transplanting, I use a clean tray and new deeper insert, to allow the plant room to grow. I through out the inserts, but use trays over after sterilizing with bleach and warm water. Air circulation is very important. I use fans for air circulation and to toughen the plants.
DH is a big yogurt eater so I save all the empty individual yogurt cups and use them as pots. I just use a hot soldering iron to make a hole in the bottom for drainage. Depending on the size needed you can use dixie cups, empty medicine dispensing cups, and if someone is doing a food demo in your local Sam's or Costco just ask if you can have the empty plastic cups for seed starts. I use them all the time to set down cuttings and African Violet leaves. I haven't had good results with peat pots and the few that my mother gave me are headed for the trash can.
After I posted this earlier , I read through this , Here's my 2 cents input .
Sometimes mold is not mold , it is the peat fiber trying to regenerate ,, (it could be argued moss is a mold ) however ,, presoaking and setting peat pots in a tray can sometimes help .
The half of the picture closest to you and what it is farther away and green ,, This happens a lot with moss and it will take a lot more light in humidity than most will have thought about (previously myself also ) ..
Well anyway the picture ,,