Also, with regards to damping off (which indeed, that's what this looks like), did you sterilize your mix? It's a smart thing to do. Seeds can bring their own fungi, but you avoid a lot of them in the soil if you sterilize it before planting. I only plant seedlings in heat-treated mix. Store bought potting soil might be sterilized already.

Yes, there are those who think your mix should be "teeming with life", as in marvelous microbes, but in my view the life that it is teeming with is what you don't want to mess with. I've never ever had any damping off problems with my seedlings, and they never seem to suffer from growing in a sterile medium.

As per Laura's advice, what you can do now is just allow the surface of the soil dry out. The roots are way below that.

Actually, let me amend that. Most commercially produced seeds are treated with a fungicide. "Organic" seeds might not be. As such, the former won't bring bad fungi with them, and they'll be a bit more resistant to fungus in the soil.

Thank you! I have been heavy-handed with the water--I'll be careful now!

Very interesting! I'm using organic seeds, and I've noticed white mold growing on the dirt. I need to get heat treated soil.

I wonder if you can microwave the soil before planting.

I never thought of that, but microwaving ought to work. Heated soil can be a bit smelly, especially if there is compost in it, so I usually just use the oven. It's easy to do. Bake at 200F for half an hour. You can do a whole bunch of soil, and then just keep it in sealed containers. I do a soil sterilization job exactly once each season.

Very cool, good to know. Thank you.

Hey guys! If you are starting seeds in pots, it really is best to use potting mix. Apart from all the bacteria that is in it, soil is too heavy as the particles clump together and hold too much moisture. In contrast, potting mix is light and airy it drains easily and doesn't cause rot.

Linda

It can also help to have a fan gently blowing across the seedlings. The fan will help moderate moisture/humidity and will help strengthen the stems.

>> I've noticed white mold growing on the dirt.

Yep. Conditions good for fungi means conditions bad for seedlings. Always.

>>I wonder if you can microwave the soil before planting.

I tried the oven but was told very clearly by she-who-must-be-obeyed that such a smell would not be tolerated in the future, so I nuke everything. Among other things, hot steamy water hydrates the media very quickly and well.

I have an outdoor oven that I use regularly in the summer, so she-who-must-be-obeyed isn't aware of the smell. But that's a good point. If you're going to nuke it, make sure it isn't bone dry.

You can sterilize the medium until you are blue in the face but if you overwater it will be pointless. Fungal spores are all around us in the air.

Actually, if your medium is indoors, the prevalence of fungal spores is greatly reduced compared with outside. Especially if HVAC systems are being used, and the air is being actively cleaned with high MERV filters. Of course, those same filters can act as breeding ground for those spores, so if an overloaded filter fails, you're in trouble.

Damping off isn't caused by just any fungus. There was a recent thread about this. It is generally caused by a specific soil borne fungus, that is not ubiquitous indoors. I disagree, damping off is unlikely to be an issue in freshly sterilized potting mix even if you overwater. And most seedlings quickly outgrow the vulnerable stage as well. But anything is possible.

put a small fan blowing toward them in the room. It doesnt have to be 2 feet away and aimed right at them(although during hardening off that can be good too) Ceiling fans set to low are ideal IMO. Just any thing to keep are circulating and moving. Also do not over water and make sure you arent using a potting mix that is made to retain moisture. I start my seeds in jiffy pellets and then transplant those to 4 inch pots with miracle grow a week or 2 after they germinate. This seems to all but eliminate any damping off issues for me

Jiffy pellets are sterile and I think at least the organic MG potting mix is too (though I've heard occasional stories of insect infestations coming out of the latter). So you can sterilize your own mix, or you can buy your sterility in a bag.

My understanding from extension literature is that damping off is actually caused by a variety of pathogens -- several varieties of what are "true fungi", and also what are called oomycytes, which used to be considered fungi. These are present in virtually all native soils. I should add that damping off can occur well before the seedling stems emerge. Damping off can infect seeds underground just as they are opening, turning them to mush. We tend to write those off as bad seeds that didn't germinate, but they really did. The plants just didn't emerge from the soil.

Not to disagree but in over 40 years of starting hundreds of seedlings a year I have never sterilized or cooked or even heated any mix. The fungi are also in the air all around us so any sterilization lasts only a few minutes.

But you can control the conditions that allow the fungi to be active and aggressive as they require excess moisture (90% of us over-water out seedlings) and stagnant air. Simple to prevent - a small fan for air circ and lay off all the excess water. Do that and they die - the fungi, not the plants. :)

Dave

Dave, I'm curious what do you use for your seed starting mix? I have not ventured into making my own. The nature's care that MG sells now is cheap, organic, and works wonderfully. I don't even need to fertilize seedlings at all. I wonder if there is any benefit to making my own. I think people sometimes get a little obsessive with seed starting mix and we always see people posting here that have screwed it up in various ways. It seems like people always try to use trendy ingredients that don't drain properly and are devoid of nutrients. I'd be curious to know what works so well for you.

Damping off is also favored by cool conditions.

That's useful to know that you avoid damping off without sterilizing your soil, but I'm pretty sure that those pathogens really aren't abundant in air inside the home, unless the home is vigorously vented. This time of year, most people have their home air going through filters. Doors and windows are largely closed. The fungi don't live in the home. They live in the soil, and unless you have a lot of active soil in your house, with fans blowing on it, I have to doubt they'll effectively seed your pots through the air. That all assumes the seedlings are being grown indoors. If you're growing them outside (not many places you'd be doing that in February) all bets are off. Probably also in a greenhouse. So I'm going to maintain that if you are growing your seedlings indoors, with a standard HVAC system, the pathogens that cause damping off are largely in the mix you planted them in. With that in mind, you evidently can carefully manage moisture to avoid damping off, or you can sterilize the soil. Might be smart to do both, especially for those of us with less management experience.

I suspect that's why good quality seed-starting mix is sterilized.

I'm not sure what stagnant air has to do with it. Maybe air above the pot is too humid, because of the pot underneath it, and it's good to sweep that humid air away?

daninthedirt - I have no idea what HVAC or Merv even mean. But, like digdirt, I have never experienced damping off in years of gardening. I use bought seedling compost (medium) and recycled modules I have had for years. I have never sterilised anything. I don't possess a fan and my home has no air filters.

But I never over water and I open the windows on the greenhouse whenever possible. As digdirt says, you can't hide from the spores but you can make sure conditions do not allow them to grow.

HVAC=Heating, Ventilation and Air Conditioning. MERV=Minimum Efficiency Reporting Value, which is a standard commercial metric for HVAC filter quality. High MERV means better filters. In Texas, where we live by air conditioning (mostly central) in the summer, MERV is a common term.

I see damping off regularly outside in my climate and I used to see it occasionally indoors with unsterilized mix.

So yes, if you are not growing seedlings indoors with a U.S. standard residential HVAC system, and your growing area is heavily vented to the outside (and that certainly pertains to greenhouses!) the air will be full of fungal spores. That being said your experience and Dave's suggest that you can still avoid damping off by being careful. That's good to know. But I'm betting that if you don't want to be careful, or don't know how to be careful, you're doing yourself a favor by sterilizing your mix.

I have pretty much the same experience as Dave and floral.

Way back when... the first time I planted seeds and took cuttings, I did have some damping off. But once I learned what proper moisture looked, and felt like, and I started to mist - and water from below- instead of overhead watering, I haven't had problems since.

The fan trick was helpful for crops that stayed indoors their entire life. It forces the plant to thicken the stems and prepares it for carrying a lot of weight. As nice secondary benefits, moving air moderates heat, and promotes evaporation, thereby weakening the conditions for damping off.

I'm changing the staging area this year to my basement, so I expect I'll have to be a bit more diligent.

I buy seed starter mix, but I do reuse cell trays and transplant containers. I go to the Big Box store nurseries and ask for any containers they're tossing. Some they return to their suppliers, some they are glad to get rid of.

"Dave, I'm curious what do you use for your seed starting mix?"

We use ProMix BX almost exclusively in the greenhouses but I have also used Metro Mix 360 and even MG Potting Mix as well as several other commercial brands over the years. The crucial point IMO is NO SOIL, no dirt, in the mix. Soil-less only.

Damp-off is caused by several different fungi including fusarium, phytophthora, rhizoctonia, pythium, etc. all of which are soil borne but also air and water borne. So any sterilized mix, whether made or purchased, is compromised as soon as it is exposed to air, water, tools, pots, hands, etc. "There is fungus among us" is true be it inside or outside. :) So you deny it the conditions to grow - the excess moisture it needs, the extreme temps it needs, and the shelter from light and moving air it needs.

Dave

PS: it's also true that more seedlings are killed by over-watering than by all other causes combined. And keep in mind that a tiny seedling all alone in a way too big container for it will drown no matter what you may do. With young seedlings there is a safe ratio of container size to plant size - 2:1. A 1" plant in a 2" cell thrives if not over-watered but a 1" plant in a 4" container drowns.

Damping off is a disaster for anyone who has started their own seedlings. I like to water my seedlings using a spray bottle to moisten the surface.

Besides some of the very good pointers above I have had good luck using some hydrogen peroxide (2parts) mixed with water in a spray bottle to moisten the soil until the seed germinates.

Then watering from the bottom is very, very helpful as that keeps the surface dry. Plus the root is well below the soil surface.

I like to use rainwater but I suppose IF sterile is what you want using distilled water would be helpful.

To sterilize your own soil using a microwave or even a propane gas grill works well. Whatever method used making the soil moist is most beneficial - in a microwave it is the water that gets excited and generates the heat.

The tip of using boiling water is also helpful.

I still think the most important factors in this order are

1. Don't overwater

2. Air circulation

3. Temperature(above 65...68-75) is probably ideal

ive never nuked or baked soil either. Although I do start many things in jiffy pellets I don't for beans cucerbits or some flowers.

use good potting soil though for growing transplants. One thing I've learned with growing transplants or seedlings is, "crap in crap out" just like bargain brands at the grocery store. Sometimes you get a good bargain and sometimes you get what you pay for