seed mix question

Baytown, TX(Zone 9a)

I am new to starting my seeds this year indoors.
I have Peat & Vermiculite on hand and would like to see if anyone can give me a soil mix recipe of any kind to make my own versus buying the store bought mix.
I have these two products in a large batch and would like to use these, if I can.
Any help and/or suggestions are greatly appreciated.

This message was edited Mar 7, 2014 9:31 AM

Everett, WA(Zone 8a)

Both peat and vermiculite can crumble easily and become powdery if you work them around too much. So be gentle.

I hope the peat fibers are fairly long and coarse. If it is fine and powdery, it tends to get compacted and leave very room in the mix for air. If that happens, DON'T OVER-WATER or you'll drive all the air out and the roots will not get enough air. they will slow their growth or drown and die.

Add lots of coarse stuff to make a peaty mix better aerated and less soggy. "As much as you can afford", might be good, but 20-30% is better than 10%.

When you come right down to it, roots need plenty of air more than they need plenty of water. It's easy for roots to drown and rot, but hard for them to dry out so much that they take lasting damage.

If the vermiculite is very coarse, good, it will help "open up" the mix and let water out (faster drainage and less water retention) and let air in (roots don't drown).

But vermiculite holds a LOT of water. That means that, if you overwater, it will stay over-watered forever and your seeds and roots will rot.

Maybe the vermiculite will help you learn to NOT over-water. Add just a little water, and the vermiculite will absorb some and re-release it as the roots need it.

Better than adding vermiculite to peat is adding very coarse Perlite to peat. That can't ever crumble, and zero water can perk into the centers of the grains. This way, if you over-water by a little, the roots will only have to drink up a little water to unclog the openings and let air in. But this is a risky business: its like a man drowning in a phone booth full of water, trying to get his nose above water by drinking as fast as he can!

I like screened pine BARK even better than Perlite. I can get it as coarse as I want (2-3 mm or 1/10th" to 0.15 inch). In fact I like to substitute medium-fine bark for very fine peat. My bark drains faster and is better aerated than anyone's peat, unless they buy real classy professional mixes like Pro-Mix or Sunshine.

I use around 80% to 90% screened bark, and only a little professional peat-based mix to assure wicking.

If you have screened crushed rock available, mixing some coarse, gritty crushed rock with your peat will help it drain and help let air in. But sand (even so-called "coarse sand" is too fine to help. You want "grit" with particles bigger than 1 mm, like around 0.1".

2 mm is OK and 2.5 mm or 3 mm is great.

BB-size is getting to be bigger than ideal for small containers (0.18" or 4.6 mm).

P.S. When you plant very fine seeds like petunia or alyssum or lobellia, they have to be on the SURFACE or they will never emerge. Your seedling mix surface for fine seeds must not have cracks, crevices or openings that the seed falls into.

If your mix has a rough surface, sprinkle a little FINE vermiculite or peaty powder on top, just enough to "fill the cracks" and keep seeds from disappearing below-ground.

One genius uses a single layer of thin toilet tissue on top of the cell or flat for that purpose, and says the rootlet can push right through it. I hope to test that myself.

Once seedlings emerge, I try to make sure that my top layer is all coarse bark shreds. That acts like a surface mulch, preventing evaporation from below, but presenting a DRY surface to the seedling stem where it is vulnerable to fungus, rot or damping off.

This message was edited Mar 14, 2014 3:34 PM

This message was edited Mar 14, 2014 3:38 PM

Columbus, OH

Rick's advice to use a dry surface medium helped the survival of my seedlings substantially.

Everett, WA(Zone 8a)

Thanks, Celene!

One thing I've learned helps recover from over-watering.

Set the pots or trays on top of a water-absorbent mat with a soft, or fuzzy surface that can touch the soil THROUGH the holes in the bottom of the pot or cell. Like a cotton towel, or folded Tee shirt.

Once the absorbent fabric touches the water-logged soil, it creates a capillary "bridge" that sucks water out of the soil until the towel is as wet as the soil (and gravity helps a little, too.

rather than keep changing the towel when it gets soaked, you can dangle the towel or Tee shirt over the edge of the shelf and let it hang down and drip into some pan or tray.

Now gravity and evaporation will keep the towel from becoming water-logged, so it will pull ALL the excess water out of the cells, letting air back into your soil and letting the roots avoid drowning.

I leave a pad of cotton flannel in the bottom of all my seedling trays, all the time, for continuous protection against my bad watering habits.

Excess water drains down out of the soil and into the 1020 tray underneath, where I can suck it out with my trusty turkey baster.

In fact, the flannel pad lets me bottom water uniformly without floodig the tray. I just water until the mat is soggy, but there is no standing water. The mat carries water evenly to every cell, where it wicks upward just enough to maintain moistness, but never fill the soil's air pockets.

Post a Reply to this Thread

Please or register to post.

Upload Images to your reply

    You may upload up to 5 images