Sphagnum and peat, part II.

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Sphagnum and peat, part II.

Post by kl.. » Fri, 20 Mar 1992 13:06:12

OK, now that I'm caffienated, I'll continue.

Now you're at the Garden store, looking at bales of stuff labeled
"Peat" and "Genuine Sphagnum Peat" and "Compressed Sphagnum" and
maybe even a little bag labeled "Milled Sphagnum" that costs a
small fortune.  What do you buy?  Just to confuse the issue
further, there's also some stuff labeled "peat moss".

Of course, it depends on what you want it for.  Do you want
to keep your seedlings from damping off?  Milled Sphagnum.

Double potting?  or lining a terrarium?  Or making a topiary
form?  Or doing air-layering?  Compressed sphagnum, long-strand
sphagnum or coarse-chopped sphagnum.  (the name it goes under is

Adding organic matter to soil when you haven't got access to
compost?  Shifting the soil pH to a more acid level?  Peat,
of whatever persuasion.

What the %^&%^ is "peat moss"?  Theoretically, it's sphagnum,
long strand, chopped or milled, but it could be just about anything.
I've even seen partially decayed sedges sold as "peat moss" (yes,
that sign came down after the manager and I had a little discussion...)

Peat is the cheapest to buy.         You might pay $1.50
for a bag the size of a 50 lb dog food sack.  It'll be heavy, and
is often sold by weight.  A lot of the weight is water...   Poke a
hole in the bag, and you'll get what looks like good black dirt.
K-Mart and such usually run spring specials offering equal size
sacks of compost or peat.   I've used it on occasion to fill a
planter (mixed with sand and what passed for "soil" in that yard).
Homemade compost fills the bill for that quite nicely, and is
LOTS cheaper.     (my Scots ancestors would be proud...)

Milled sphagnum comes in small bags usually, and costs an arm and a leg
and another arm.  Weighs nothing.  Looks like dust.  Dump cold water on
it and watch it float.  Inhale it and sneeze for the next 3 years.
Dump HOT water on it, and you've got a lovely seed germination medium.
Plant on sterile any-soil, then cover the seeds with a thin layer of
milled sphagnum.  You don't need to wet it in this instance, since it
will soak up room temp water in a day or so.  The sphagnum keeps the
seeds constantly moist, yet is porous enough to allow good oxygen
penetration (an absolute requirement for germination), and has natural
antibiotic activity to keep down the nasties that will try to turn your
seedlings into their dinner...  Worth the cost, IMHO, though I mill my

I have about 1/4 of a bale of compressed long strand sphagnum that
I bought maybe 10 years ago.  It was an undoubted extravagance, but
I knew I'd use it over time.  A bale comes in a bag about the size of
2 50lb dog food sacks, and usually weighs in at about 20 lbs.
Start uncompressing the stuff, and you get enough to fill 5 55 gallon
garbage cans (believe me, I've done it at the greenhouse often enough).
Last time I looked at the price around here, it was about $15/bale.
I use it for lining gift terraria, for double-potting plants, for
air layering, and I also rub it on a screen and collect all the little
pieces to make my own milled sphagnum.  Oh yes, I'm trying to get some
_Nepenthes_ (Malaysian pitcher plants) cuttings to root, and they're
in that.  Have been for a year.  They've JUST initiated roots.  The tops
are fine, though, and part of the reason is that they've been in sphagnum.

Long strand sphagnum is just whole, dried sphagnum plants.  If you pick out
one strand, it'll look about like coarse chenille.  It won't soak up cold
water readily (I usually put what I think I need in a bucket, then
dump boiling water on it -- by the time the moss is cool enough to handle,
it's fully saturated.  Pick up a handful and let it drain.  It holds an
incredible amount of water.  Squeeze it and you'll get more water out
of the moss than you will out of a kitchen sponge.   Great stuff.  Very
versatile, and alas, no substitutes seem to be anywhere near as good.

BTW, expect to see "straw" and leaves in a bale of sphagnum.  Won't hurt.
You shouldn't see more than 1-2% though.

Kay Klier   Biology Dept  UNI