Peat - as a starting medium

[huntsman]

Has anyone tried peat exclusively as a starting medium?

I've had great results with peppers and was hoping 'maters would be the same...

[brog]

I`ve had good luck with peat, but you have to have it wet-wet wet, then lightly sqeeze it in your hand when filling your planter,( better to let it set over nite wet.). After planting I bottom water ever 2 days with planter covered with cling wrap- clear plastic or glass. I have better luck when I mix 1 part sand and 2 parts peat. I ALWAYS cover my seed with one quarter inch of sand and let the sand dry out when the seed come up, continue bottom watering ( damp not wet) as needed, take planter out of water as soon as top of sand becomes damp. keeping sand dry keeps out disease. Good luck Bill

[huntsman]

Hey Bill -

Nice idea with the sand. Just normal soil I guess?

[dice]

Peat pellets are exlusively peat. Some people use them:
http://amars-world.com/?attachment_id=4778

Once peat dries out completely, it takes awhile for it to soak up
water again (somewhat hydrophobic). Where you find peat moss
used in professional commercial seed-starting mix, a wetting agent
(like yucca extract, or some synthetic equivalent) is often added.

It also has virtually zero nutrition, so if your seedlings are going
to be under lights or in a cold frame or greenhouse for several
weeks before transplanting, they will probably need some mild
fertilizer. I had reasonably good results last year sprouting seeds
in pure coir (similar to peat, holds water better, no nutrition), then
potting up into 3/4 coir, 1/4 earthworm castings once they had a
true set of leaves.

There are cheaper seed-starting fertilizers than earthworm castings,
but using that for a seedling nutrition source guarantees that you are
not going to burn your seedlings with excess fertilizer (and I have a
worm bin where I recycle kitchen waste, etc, so that reduces the cost
of the earthworm castings for me). 1/4 strength liquid fish emulsion, fish+kelp, or simply liquified kelp are often used for this too (fish can
attract small animals, so something to be wary of).

The 1/4-inch of sand on top mentioned by brog prevents gnats (tiny flies)
from laying eggs in your seed-starting mix. (Gnat larvae will chew on
fine root hairs.)

I like to do the initial wetting with mild hydrogen peroxide solution (like
3% drugstore hydrogen peroxide mixed 1 part to 10 parts water). The
hydrogen peroxide will all have reacted with organic matter in the seed
starting medium by the time the seeds sprout, and that kills damping off
fungi that may sprout from spores as soon as the peat, coir, or other
seed-starting medium is moistened.

[huntsman]

Hey dice -

So, when I first stand the seedling trays and grow mix in water, that's when I do the H2O2 solution? What about subsequent waterings?

[RayR]

Straight Peat Moss is typically very acidic depending on where it is harvested. Wouldn't you want to add some lime to balance the PH like premixed peat based seed starting mixes?
I guess it would help to know the typical PH of the peat from the manufacturer first.

[huntsman]

I'm in darkest Africa, Ray - that kind of info is seldom noted, but I get your point. Is there anything I can add from a packet....and how much would I add?

That's exactly why I posed this thread - my peppers love peat, but I wasn't sure about 'maters...

[RayR]

I don't know, Peat Moss is harvested in different parts of the world and PH can vary greatly.
A quick search shows that there are Seven species that grow in southern Africa
I guess the fact that your peppers do well in the straight peat that you have available means the PH can't be that low. Maybe it has already been PH balanced in the form you are buying it?
Peppers and Tomatoes have similar requirements, so you could experiment with Tomatoes and see what happens.

[huntsman]

Oh, ok.

I had this idea that peppers and 'maters grew in very different soils, but that might have been a case of misunderstanding in the first place. :-)

[dice]

Originally Posted by huntsman

So, when I first stand the seedling trays and grow mix in water, that's when I do the H2O2 solution?

Yes.

What about subsequent waterings?

Probably not needed unless it is a very wet and humid environment
and you see mold growing on top of the seed-starting medium.

Once you pot up into 3-4" containers, you want to skip the hydrogen
peroxide after that. Any beneficial bacteria and fungi are needed to
break down organic compounds in mild organic fertilizers, etc, and
hydrogen peroxide would kill those as well as pathogenic fungi that
cause damping off. (I add a microbe spore mix to the seedlings when
potting up into 3" pots that has mycorrhizae, beneficial bacteria, etc
in it, so I definitely do not want to kill those off with hydrogen peroxide.
I want them to get a headstart on populating the media around the roots
of the seedlings before they ever go into the garden.)

I find descriptions of pH for peat moss ranging from 3.0 to 5.5. Some
wood ash in the peat or water would adjust pH up, but wood ash is very
fast acting, and it is easy to overdo it. It would probably be wiser to
sprinkle a little dolomite lime into the peat and mix it in, maybe a cup
or two to a wheelbarrow full of peat, or a pinch of it in a 3" pot. Dolomite
lime breaks down slowly enough that it will probably not dramatically
affect the pH that the seedlings see, only nudge it upward a little.

[fortyonenorth]

Dice - correct me if I'm wrong on this...

I don't think the pH of peat would be an inhibiting factor for the relatively short time your plants will be in containers prior to transplanting. Adverse pH (high or low) limits availability of soil nutrients. If you're using very small amounts of liquid ferts and/or foliar applications, this shouldn't be an issue. Dolomite lime takes three years to fully break down. So, as others have pointed out, any added lime will have almost no immediate effect.

Having said this, I don't think peat is an ideal seed starting medium - unless your growing blueberries or something similar. If you have access to a bona fid seed starting mix, there are going to be far fewer potential issues.

[RayR]

I think you guys are underestimating the effect that lime has on the acidity of peat, Here's a good read on that subject.

Peat + Lime + Water = instant chemical reactions

[fortyonenorth]

I didn't read through the article - and maybe this was mentioned - but lime's effect on pH is subject to many factors. Chief among these is the type of lime. Hydrated lime will act much quicker than Dolomite, for example. But, I wouldn't recommend using HL in a seed starting mix. Screen size (i.e. how fine the lime is) is another contributing factor to how quickly it will act. And, I agree, there is an immediate chemical reaction. With **typical** dolomite lime, the 3-year figure is the conventionally accepted term for complete breakdown.

My main point was, if a good seed starting medium is available and affordable, why use peat? If you desire a peat-based mix, I would suggest using a pre-mixed potting soil perhaps with the addition of extra perlite. In most cases, the potting mix will be pH adjusted and include yucca extract or another wetting agent.

[RayR]

The study that was done showed that between 24-48 hours after liming the peat (they used chalk and ground limestone) the PH of the brown peat went from 4.5 to 7.4 and the black peat went from a PH of 6.5 to 8.0. That's pretty fast.

I agree that the type of lime will be a factor, Dolomite has a good amount of Magnesium in it and that slows down the acid neutralizing effect of the Calcium.
Ditto on using something that is already around neutral PH like seed starting mix or potting soil. Even compost would be good. Huntsman like he said is in deep dark Africa, so I don't know what is available to him.

[huntsman]

Thanks dice -

Good info as always.

Just for clarity guys, I'm not limited to peat at all, but as I have about 50kg of peat (when dry) I wanted to know my options. ;-)