Seed starting mix

[JayneR13]

@pepperhead212 Not necessarily. You're sterilizing seed starting mix that might have been previously sterilized. I was sterilizing oak pellets, which were unlikely to have been previously sterilized. Mushrooms like hardwood substrates. That's an entirely different thing.

[brownrexx]

@JayneR13 mold spores should be killed at about 160° for 25 minutes. Anything more than that will not kill them any better. Dead is dead!
If you are getting mold after 300° sterilization, then the mold spores are entering your media and growing AFTER sterilization.

Mold spores are in the air everywhere and when they have the proper conditions like cool and damp then they will grow.

Previous sterilization should make no difference.

[Uncle_Feist]

I've used promix bx from start to finish for at least 3 decades at this point with zero problems.

Back when I first started everyone always steered people towards jiffy mix for all seed starting. Seems every single year there was damping off issues because jiffy would settle down tight and waterlog. Promix bx won't do that. I even use the promix in plug trays that I usually end up floating in a water bed built on a bench the length of one side of my greenhouse.

[westside bengal]

I've used promix bx from start to finish for at least 3 decades at this point with zero problems.

Back when I first started everyone always steered people towards jiffy mix for all seed starting. Seems every single year there was damping off issues because jiffy would settle down tight and waterlog. Promix bx won't do that. I even use the promix in plug trays that I usually end up floating in a water bed built on a bench the length of one side of my greenhouse.

BX for me for years also. I have tried Pro Mix HP which is same as BX with additional perlite which was OK. Over the last few years I have noticed more sticks and roots in the bag and for seed starting I screen that stuff out but that is all.

Now when I pot up my plants I throw a handful of Happy Frog or Ocean Forest into the mix to juice it up a bit.

[JayneR13]

@brownrexx From what I've read in Stamets and learned in college lab, I beg to disagree. Spores of any kind are very hard to kill. It takes 15 psi and the high temperatures that come with it to kill spores. Nowhere in my Stamets book does he recommend oven sterilization. He does give a technique for straw pasteurization that involves boiling water at that temperature, but that's not to kill spores. He discusses pasteurization on pp 169-174 of his Growing Gourmet and Medicinal Mushrooms book, and states clearly that pasteurization does not kill spores. That technique is used to selectively kill off populations of temperature-sensitive microorganisms. He also points out that if the medium isn't colonized within about two weeks, contaminating microbes will take over. He has six categories of contamination sources, including what he calls Mobile Contamination Units, aka children.

Sterilized media that's oven sterilized may benefit because the primary sterilization was likely done in an autoclave using pressure and high temperatures. Granted spores could drop into the media along the way after the bag is opened, but before then the media shouldn't have that issue. Stuff happens, of course, as did likely did with my Espoma. Sometimes we just get bad media, and oven sterilization won't help. Not to kill spores, at least.

[brownrexx]

@JayneR13 Living mold can be killed at 160°F and if high temps can not kill that spores it does not make much sense to me to cook the substrate at 300° for 3 hours. Spores of any kind can be notoriously hard to kill but generally they will remain dormant until the right conditions exist. In the case of mold, the right conditions will be cool and damp.

So since we can't kill mold spores with oven sterilization, then I guess controlling the conditions for their growth is the best bet. I have noticed that many of the people who experience damping off are germinating their seeds in cool basements. I am a proponent of germinating in a warmer environment to prevent molds. This is not 100 guaranteed but I think that it helps tremendously.

[JayneR13]

Funny how you specified mold spores in your first post on the subject and have now walked it back to living mold, once confronted with expert reference. But whatever. I’ll follow my references. Your garden, your rules. You’re giving poor advice though, at least on this subject. I stated quite clearly that oven sterilization didn’t work, even at 300 for 3 hours.

[zeuspaul]

I came upon this and found it to be a good read. They did a comparison grow test.

Best Seed Starting Mixes: Guide & Recommendations
Updated January 30, 2019

We tested eleven different purchased seed starting/germinating mixes, as well as potting mix, garden soil, and a variety of home-made mixes. While we can’t comment on the make-up of the mixes (other than noting what the manufacturer indicates is in the package), here are our observations about the look and feel of each mix, how it reacted when moistened and placed in pots, how well it retained moisture, and how well seeds germinated and grew in it.

<snip>

https://gardeningproductsreview.com/bes ... ing-mixes/

[brownrexx]

Funny how you specified mold spores in your first post on the subject and have now walked it back to living mold, once confronted with expert reference. But whatever. I’ll follow my references. Your garden, your rules. You’re giving poor advice though, at least on this subject. I stated quite clearly that oven sterilization didn’t work, even at 300 for 3 hours.

Geeze, that is kind of a snarky response. Seems like you are looking for an argument.

I changed it to living mold after reading your response and realizing that it was probably true about the spores and not because I was "confronted with expert reference". Sheesh.

I wonder why you even bothered to try oven sterilization though since you apparently know that it won't kill spores.

[brownrexx]

Funny how you specified mold spores in your first post on the subject and have now walked it back to living mold, once confronted with expert reference. But whatever. I’ll follow my references. Your garden, your rules. You’re giving poor advice though, at least on this subject. I stated quite clearly that oven sterilization didn’t work, even at 300 for 3 hours.

Geeze, that is kind of a snarky response. Seems like you are looking for an argument.

I changed it to living mold for the sake of accuracy after reading your response and realizing that it was probably true about the spores and not because I was "confronted with expert reference". Sheesh.

I wonder why you even bothered to try oven sterilization though since you apparently knew that it won't kill spores.

[Cranraspberry]

I thought I’d update with some very unscientific results. We had to leave for a few days and I had no choice but to water the seedlings heavily and hope for the best. The batch that had peat mix only got algae, mold and I lost another chard seedling. The batch that had a mix of peat seed starting mix, coir and pine fines as well as some extra perlite didn’t get any mold/algae and everything survived.

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[Greatgardens]

I bought a small bag of two Schultz products for seed starting tests: Cactus Potting Mix and Orchid Mix. The cactus mix has what appears to be fairly large peat + quite a bit of perlite. The orchid mix has large peat, and woody pieces and no perlite that I can see. They both drain pretty well (small test). I planted some Linda (mini-dwarf) seeds using the cactus mix. I also added some TomatoTone gramular fertilizer to the mix. From what I can see, this "Cactus mix" could be duplicated easily with regular Miracle-Gro Potting Mix + a good dose of perlite. For my wife's cactus, I usually mix approximately equal volumes of sand, regular potting mix, and perlite. If I were to use it for seed starting, I think I'd want to at least double the peat addition. I usually get into trouble from over watering by the one month mark, so we'll see if this helps.

[Cranraspberry]

I’ve been having pretty good luck with my “enhanced” seed starting mix concoction. When I have the fan running all day I think it might dry out almost TOO fast! But no more damping off/mold/overwatering issues to date. Just started my pepper and eggplant seeds in the same mix, we’ll see how that goes.

[Old chef]

Hello
Anyone ever use Pittmoss? it is Peat free

Old Chef

[zeuspaul]

I had a 2 CF bag of groundcover bark that was about two years old. I sifted some with a #4 or #5 sieve. I ended up with a lot of stuff that looked like peat moss. The larger bark (1/4+/- inch) nuggets might act a bit like perlite making the combination a good base for a starting mix.

I purchased three more bags of the same product from Lowes. Five bucks for two cubic feet of a potting ingredient is a very good price. After opening a bag I was surprised to find a bag full of shredded wood nothing like the bark nuggets in my old bag of the same named product.

I did some research and read reviews and I hear the same complaints. I searched Lowes and Home Depot for other bark products even for larger sizes to no avail. HD did have a bark product of a larger size but reading the reviews it is also shredded wood

I am very disappointed. Bark has been a primary ingredient in my container mixes and I was looking forward to also using it in my starting mixes. Hopefully this is temporary.

Also to add to the mix I purchased 2 CF of perlite from HD for $18 (free shipping). Using a #4 or #5 sieve I sifted the perlite and ended up with a lot of the smaller sized perlite.

The bark fines and the fine perlite are good additions to my starting mixes.

[GoDawgs]

Last year I started using Happy Frog potting mix for seed starting and it's working really well. It's probably not fine enough for some people but I like it. It's working just fine this year so far. My local feed and seed carries it.

https://www.groworganic.com/products/ha ... om-foxfarm

The old favorite mix I had used for years changed with lots of larger bark chunks and twig pieces added. No thanks!

[Greatgardens]

So far, my Schultz Cactus Potting Mix is doing great. Plants are just now at the first true leaf stage, and they are nice and green, and look great. I also think that part of the reason is the addition of Tomato Tone to the mix. I've got a dozen plants doing well, and germination was great, too. (I do cover the seeds with a small amount of Vermiculite.) If things keep going well, I'll post some pics after the plants are a bit larger.

[AKgardener]

I use sunshine mix #4 this time around I dont know if its the mix or the seeds but Im having mix on things.. peppers no problem herbs no problem cucumbers no problem.. my only issue is matter have arnt popping ip if they do there is only one leaf or there helmet heads.. and when and if they make it i pot them up in the same mix and well lets say I never got to have my winter mater cause the plants are just dying...first year I struggled this bad so I bought alaska earth soil called the company so double check if I can use it indoors and for my seed starting they said yes and told me to add worm casting as well.. so today Im tranfering stuff and praying my maters take off

[Cranraspberry]

I planted out some seedlings today, and the difference between all peat starting mix and peat+coir+pine fines was huge! The combo mix was very crumbly even when moist, but cells with the standard starting mix in the same tray were very wet and the peat was a homogeneous clump, even when there were no roots. I’m definitely going to continue cutting peat-based mixes, but the next batch will be heavier on peat since the batch I have now dries out a little too fast I think. Wish I had taken some pictures!

[CrazyAboutOrchids]

I've switched around a few times trying different products but came back to what's always worked best for me. I start my seeds in Fox Farms Light Warrior. When I pot them into their first cups, I mix Fox Farms Happy Frog with a bit of Ocean Forest. When I do my second pot up, it's that mix stuck into all Ocean Forest.