Just for fun I decided to compare 4 homemade potting soils by criteria in a
Fine Gardening article, which unfortunately wasn't explicit enough on a few
points, so I'm not sure I did the tests as she had in mind. Anyway, here's
what I did, and I'd be interested in how people would interpret the results.
For porosity,I was supposed to fill a quart jar w/ "dry potting soil", tho
later in another test on response to watering she says not to judge
peat-based mixes just out of the bag, but to wet it beforehand. She didn't
say this about the porosity test, so I'm not sure what I was supposed to do.
I left the peat dry.
Then I was supposed to fill the jar w/ as much water as I could before
overflowing, hopefully at least 2 cups, then tip the jar and see how much
drains out w/i a few minutes. This sounded like immediately tipping, but a
picture caption reads"ideally... add about 2 cups of water...a few minutes
later you can drain off about 1 cup" , which made it sound like it sits for
a few minutes, so I then put that water back in, let it sit for a few
minutes, then tipped it again.
A website mentioned that a cup of water should flow thru a quart of mix per
minute, so after draining off the above water I put the mix in a quart-size
flowerpot and added another cup to see how much would come out in a minute.
Here are the results:
sample 1: immediate runoff: 1c runoff after sitting a few minutes: 1/2 c
amt of water draining off in 1 minute after adding 1c: bit more than 3/4c
sample 2:immediate runoff: 1c runoff after sitting a few minutes: 3/4 c
amt of water draining off in 1 minute after adding 1c: 3/8c
sample 3:immediate runoff: 3/4c runoff after sitting a few minutes: bit
more
than 7/8c
amt of water draining off in 1 minute after adding 1c: bit more than 1/2c
sample 4:immediate runoff: 7/8c runoff after sitting a few minutes: close
to 1c
amt of water draining off in 1 minute after adding 1c: close to 3/4c
1:equal parts soil, sand, perlite, and peat
2: equal parts soil, compost, sand, perlite
3: equal parts soil, compost, perlite, peat
4:equal parts soil, perlite, peat, bagged composted manure
All ingredients were screened thru 1/4 mesh.
I'm planning on filling large containers with this mix to grow basils,
Vietnamese coriander, and
culantro (8 to 30 gal containers)
Any opinions, say on which is best and second best?
Thanks
Peg Daniels
peg-gary@mindspring.com
Just for fun I decided to compare 4 homemade potting soils by criteria in a
Fine Gardening article, which unfortunately wasn't explicit enough on a few
points, so I'm not sure I did the tests as she had in mind. Anyway, here's
what I did, and I'd be interested in how people would interpret the results.
For porosity,I was supposed to fill a quart jar w/ "dry potting soil", tho
later in another test on response to watering she says not to judge
peat-based mixes just out of the bag, but to wet it beforehand. She didn't
say this about the porosity test, so I'm not sure what I was supposed to do.
I left the peat dry.
Then I was supposed to fill the jar w/ as much water as I could before
overflowing, hopefully at least 2 cups, then tip the jar and see how much
drains out w/i a few minutes. This sounded like immediately tipping, but a
picture caption reads"ideally... add about 2 cups of water...a few minutes
later you can drain off about 1 cup" , which made it sound like it sits for
a few minutes, so I then put that water back in, let it sit for a few
minutes, then tipped it again.
A website mentioned that a cup of water should flow thru a quart of mix per
minute, so after draining off the above water I put the mix in a quart-size
flowerpot and added another cup to see how much would come out in a minute.
Here are the results:
sample 1: immediate runoff: 1c runoff after sitting a few minutes: 1/2 c
amt of water draining off in 1 minute after adding 1c: bit more than 3/4c
sample 2:immediate runoff: 1c runoff after sitting a few minutes: 3/4 c
amt of water draining off in 1 minute after adding 1c: 3/8c
sample 3:immediate runoff: 3/4c runoff after sitting a few minutes: bit
more
than 7/8c
amt of water draining off in 1 minute after adding 1c: bit more than 1/2c
sample 4:immediate runoff: 7/8c runoff after sitting a few minutes: close
to 1c
amt of water draining off in 1 minute after adding 1c: close to 3/4c
1:equal parts soil, sand, perlite, and peat
2: equal parts soil, compost, sand, perlite
3: equal parts soil, compost, perlite, peat
4:equal parts soil, perlite, peat, bagged composted manure
All ingredients were screened thru 1/4 mesh.
I'm planning on filling large containers with this mix to grow basils,
Vietnamese coriander, and
culantro (8 to 30 gal containers)
Any opinions, say on which is best and second best?
Thanks
Peg Daniels
peg-gary@mindspring.com
Ok.....you were testing the percolation rates of your different mixes,,,
That test ought best be performed , I think, using the containers you
will be using to put the cliantro/basil in..... this will give you good
idea if drainage holes are adequate.
just get all the different mixes into the containers, get them soppping wet-
till your sure they- 're thoroughly wet, the wait till they stop
dripping( i guess they will have to be suspended somehow ,so as to determine
this.
Once they all stop dripping add a predetermined amount of water to each
container- enuf to cause drainage out thte bottom of the mix>>. take your
measurement yes the mixes should have already been wet for this to work,,
peat is notorioiusly ddry out of the bag- taking hours or days to wet
depending on what yoa got to go w/ it to help it out.... That's alot of
work,,, I can say w/ cerainty that most of your recepis will perc ok, less
yuour soil is like mine( high sodium)
gypsum bill
Personally, I'd go with #4 except replace the peat (no nutrient
value; low pH) with compost and add some coarse sand:-)
I don't generally use much soil in my potting mixes, but I'm not
growing food type crops, either - depends on what your soil is.
Object with potting soil is that the water you put in drains out
almost immediately, while wetting the mix because soggy roots will
kill plants and so will too dry a mix. So, you want a mix that
retains moisture, but has sufficient porosity that water drains
through fast. I use granite grit instead of perlite, but if you
can't get grit, perlite will do. I don't like it because it tends to
float to the top of the mix after a while.
You can also replace the peat element with pine bark fines or pine
bark mulch - many nurseries pot in pine bark these days. Peat, IMO,
is not a marvelous additive to potting soils - yes, I know most
bagged mixes are peat based - but it tends to degrade and become a
rather mucky mess after a while, plus if it dries out, it's very hard
to re-wet. If all you can get are bagged mixes, you have to live
with it, but if you're mixing your own and have access to compost,
leaf mould, etc., there is no reason to use it. It adds nothing to
the mix for the plant except acidity for those plants to require
that.
Marge Talt, zone 7 Maryland
mtalt@hort.net
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basils,
Thanks so much!
Peg
