>> I actually do mess around with the first part of the pro mix that I add to the potting soil and then I just add more promix.

Great, that removes any risk that the changeover will be so abrupt as to interfere with capillary "connectedness".

>> Does hydrogen peroxide help anaerobic soil.

I read that in many places, and finally read it somewhere that REALLY seemed to know what they were talking about. And it makes sense. 2 H2O2 --> 2 H2O + O2.

>> the odor told me it was anaerobic.

The nose knows.

>> I decided to hit it with some H2O2. A day later the soil smelled very fresh again. Is this soil now usable??

Maybe or probably. Has the water evaporated enough that the mix is light and filled with air again?

Maybe the H2O2 only killed enough microbes that they aren't fermenting enough to stink enough for you to detect.

Either way, I would first remove enough water to let the air back in! And turn it and spread it around enough so that the fermentation products (root-hair poison!) can evaporate.

I think the careful answer is that you should FLUSH away the fermentation products, then drain and dry it so it's aerobic again.

The more careful answer would be that it only stunk if enough bacteria grew in it to produce enough acid and alcohol for a human nose to detect. That's kind of a lot of microbes. Did you want fairly sterile seed-starting mix, or just potting soil? I would not worry about using it as p;otting soil, with good drainage.

Now my drainage fetish comes out full-force.

ANY mix will go anaerobic or hypoxic if the mix is water-logged. If the voids fill with water, there is NO air. If the voids MOSTLY fill with water, air can't diffuse through channels into the lower inches of the mix. Again, no oxygen. Dead roots. Soil bacteria fermenting instead of oxidizing humus and releasing nutrients. Mycorrhiza suffocating instead of helping roots absorb water and nutrients.

Either never water containers enough to saturate the mix, or provide adequate drainage so that excess water drains away. That's as important to a plant as never holding your head completely underwater for longer than 5 minutes.

I like to add bark nuggets or chips or shreds to open up peat-based mixes. Others like coarse Perlite.

I actually like a fairly fine mix for germinating seeds. My favorites are Gardener's Supply Germinating Mix, and Metro Mix 300. The former is much easier to purchase than the latter in my area. Some of the other Metro Mix types are great for transplanting, but I find them too "chunky" for seed starting. The Gardener's Supply mix is my old stand-by for seed-starting. Have been using it for several years, and have had no need to put something finer on the surface. I use bottom-watering only until the plants are large enough to transplant, and have never had a problem.

I've used the GS mix in cell packs, APS systems, and various other seed-starting methods. It's worked well with all types/sizes of seeds.

Linda

Linda, you must have mastered the art of NOT over-watering.

That one still escapes me.

Rick:; I grow about 1200 seedlings every year for our Master Gardeners group. Never a problem with damping off or other issues. Steady bottom watering is the key. Nothing gets top watered until well into larger pots and put outdoors.

You really need to consider something like Gardeners Supply APS. There is very little chance of overwatering. I do use a lot of 1020 trays with capillary mats an cell packs as well. Just so everything is evenly moist; the mats do not need to have standing water on them to be effective.

Gosh, this thread is freaking me out! I was not prepared to winter sow. So when it came time for me to sow and I went shopping for planting medium there wasn't much to choose from. I didn't panic because I read on Wintersown.org to just plant in what you have. I ended up with Scotts potting mix with moisture control. When I actually went to sow with it I didn't like the texture. So I went back out shopping hoping to get ProMix. Still couldn't find any. Got some Miracle Grow moisture control potting mix and one bag of Miracle Grow organic potting mix. I mixed the Scotts and the organic MG. Put it on the bottoms. Used the MG on top. I did my first 50 some jugs this way.

Then I was reading that Miracle Grow potting mix was NOT GOOD for winter sowing. Well, not much I could do at that point about what had been done.

I was finally able to find some ProMix. So I put some MG on bottom and Promix on top for my next batch of sowing. Geeeze, now I'm starting to freak out about that. I'm going to be super bummed if I messed up another 40 some jugs!!

I keep telling myself NOT to overthink this stuff! Rick, you are making that very hard

I started using cotton flannel in 1020 trays last year and doing some bottom watering. That helped, and itg especially helped that the flannel wicked away what would otherwise have been excess perched water in the bottom half of the cell.

But it was mixing in bark a year or so before that, that stopped my seeds from rotting and stems from damping off. That in initial delightful success made it "my way" and I'm slow to set aside an innovation that made a night-and-day difference for me. I'm still too proud of it!

I think it also helped that I stopped using a bag of Miracle-Gro seedling mix that, I swear, was like finely powdered peat. Recently I bought a local mix form Steubers that looked about 20 times better than that peat powder.

So maybe the better mix and cotton capillary mat would work by themselves if I never watered the cells until water came out the bottom. After all, a seed-starting cell can't accumulate toxic levels of salt the way a permanent container can. But I think it may take a few thousand seedlings for me to actually break the over-watering habit.

I know the bigger chunks are "wasted space" as far as root hairs are concerned.
I only add a little, finer, bark to Petunia and Alyssum cells.

As far as I know, I'm the only person who thinks bark is better than sliced bread for seedlings. Containers and heavy clay in raised beds, sure, I'm not crazy to use it there.

If I start weaning myself away from it now, I might eliminate the bark-and-overwater habits by the time I retire. But then finances will drive me to start using bark again.

Jennifer,

If the two different kinds of mix are reasonably similar in ingredients and coarseness, I wouldn't be too concerned about them not wicking water back and forth. That probably won't be a problem.

I certainly do over-think everything - that's my style and one of the main joys in my life.

I don't know wintersowing, but aren't there drain holes, and something to keep excess rain off? If the mixes drain reasonably well, shouldn't that drain well enough to let air back into the mix?

If you're still worried, maybe cover them during heavy rains to keep them drier.

Next year, if the mix you buy doesn't look like it drains well, you might add Perlite or grit or anything coarse to help its drainage.

By all means, for sure and certainly, please go by your experience and not by the perhaps wacky way I work around my own eccentricities.

Boil down everything I said into "seedling mixes should drain well enough to let excess water out and air in".

I think the more experienced people just avoid over-watering!

(Now this IS over-thinking, but if you're still worried, sit the jugs on top of something water-absorbent like a cotton sheet. That will wick excess water out of the jugs and help it drain away, even IF the mix is so fine that it tne4ds to get water-logged.)

Well, I did put like a million holes the the bottoms of my jugs! My husband was like "I don't know much about all this stuff but that seems like over kill" And then I have them in crates with holes too.

They do seem to drain very well. But I confess when we had three days of super rain early this week I did cover them for part of it.

Next year I will make my own soil mix and I will feel much better about that.

>> And then I have them in crates with holes too.

I think that kind of elevation is good for drainage. The jugs will never sit in a puddle. And the plastic of the jug makes good contact with the plastic of the crate, so water should form a continuous capillary layer right down to what the crate sits on.

If you want to go crazy, put a little cotton cloth as a wick under each jug ... but better just not to worry.

Al (Tapla) suggested once that you can check a large container for excess perched water by tilting it. If much water drains out the low corner, maybe it was a little waterlogged.

Or hold the jug up around eye level, then move it rapidly down to waist level and stop it as fast as possible. If the inertia of the water makes any "keep going" and much trickles out the bottom, maybe there was some excess in the jug.

Of course, I'm suggesting these mainly to amuse your husband!

But you could tell him it's an inertial damping maneuver, and if he's a Star Trek fan, you might blow his mind.

Or de-dampening.

Jennifer, I've belonged to GWeb for a long time, and most of the wintersowers there use Miracle Grow, though usually not the moisture control one. Most nurseries don't seem to keep the professional potting mixes (ProMix, Fafard, MetroMix) on display. Most only have MG on display for sale to customers. But if you ask what they use for their own growing, it's always a professional mix. If you ask, I've found all of them willing to sell me a bag or bale. Another good place to find them is hydroponics stores.

My real problem with watering is absolute negligence. I let things die of thirst way too often. This year my coleus cuttings have barely limped through alive due to repeated drying and leaf drop. I repotted them, adding some expanded shale and I see a noticeable improvement. Expanded shale retains moisture, retains oxygen, drains well. It's only been a few weeks but so far I'm impressed by what I see.
Expanded shale
The thread "Expanded shale" in All Things Gardening forum

Karen

Sometimes my winter sow seeds are better off because I can't mess with them

Mine, too. Mother Nature is a much better plant mom than I am.

Karen

By the way, you can always get the soil-less mixes at a hydroponic store.

Karen,

I found it helpful, just starting to set up a minimal spray irrigation system on a $15 Gilmore wind-up timer. It will run the sprayers for 10-90 minutes and shut itself off. Since it isn't battery based, I trust it. Sine it isn't hard-wired to 120 V household AC, it doesn't cost $175.

I just have to twist it and walk away. I remember much more often, when it is so easy. And by watering thoroughly (gradually and without puddling or runoff), it can go longer between waterings.

I just started last summer, and it has been a big help even only partially set up.

But there is up-front cost. And I can't set it to water every third day while I go away for a week.

One side benefit is that, now that I've run some 3/4" and 1/2" black plastic lines around the house, I have a hose fitting EVERY where I might want one. No dragging hoses, and no long hoses needed. Even when I just want hand-water one spot, there is a short length of hose and a hand sprayer near every bed.

(I bought some hose repair fittings and cut my longest hose into several short lengths.)

Yes, I have a timer like that.

My outdoor stuff fares much better than the indoor ones. Outside, bigger containers, and as such they hold moisture well. It's those blasted small, shallow things inside under lights. I don't want to overwater, and I ignore them way too long.

And except in severe heat and drought like last summer, my in-ground plants do well. My clay holds water well on it's own. And I've been ammending it with my homemade compost for almost 30 years.

Karen

Ohhhh, indoors plants. The only reason I don't have that problem is that my light shelf is in m y bedroom, and I fuss with those every day.

My few house plants die mercifully quick deaths. Once I had a cactus die of thirst!

Karen,Is that expanded shale something like chicken grit?I would like to get hold of some.I didn't get a chance to read all that thoroughly .Always open to trying something different ,if it isn't expensive.I don't like to put more into growing supplies than buying plants at greenhouse..
sNs..

sewNsew: I've never seen or used chicken grit so I don't know much about it. And this is my first try with expanded shale but I can see definite improvement in my pathetic coleus since using it. So far I'm kind of impressed. This is the brand I found locally at a hydroponics store.
http://wormsway.com/detail.asp...

There is discussion of it here.
The thread "Expanded shale" in All Things Gardening forum

Karen

Chicken grit is just crushed granite. It only holds a little water on its rough surface

Expanded shale, clay and slate (ESCS) are "puffed" so they are filled with bubbles and channels. Like porous Perlite, or vermiculite that's hard-as-rock. It's much lighter than soil, especially when dry.

They hold much more water than grit, but still improve drainage because they are hard little grains.

I think they improve aeration partly because they are coarser than clay, silt or sand, and also because they suck water into the inside of each grain, pulling it out of the air spaces between grains and clods.

I think they come in all different sizes, some as big as pebbles.

They have a trade association, the "ESCS Institute" with a lot of literature.

http://www.escsi.org/default.a...
http://www.escsi.org/ContentPa...