What's the difference and when should one be used in preference to the
other? As I understand it, both perform the same function - that is to
improve drainage; should the former be used with cuttings and the latter
with more established plants (i.e. if you're repotting)? My father appears
to use them interchangeably but I reckon that, if they could both be used
for identical tasks, then why would they both be sold? I was potting on some
mystery plants (mystery because they were something new I'd bought and I'd
lost the packet and brain fog means I forget my own name sometimes!) and I
didn't know which to use, so I used vermiculite simply because we had more
of it.

So could someone please explain the difference to me (Monty Don only appears
to use vermiculite - I was hoping he'd use perlite for something so I could
fathom it out for myself)?

Thanks

--
In memory of MS MVP Alex Nichol: http://www.dts-l.org/

My understanding is that Perlite does not hold nutrients/water well and so
it's main role is to aid aeration and drainage, whilst Vermiculite holds
some water/nutrient and so also helps keep the compost moist and buffer
nutrient levels.

In article , Henry writes

My understanding is that Perlite does not hold nutrients/water well and so
it's main role is to aid aeration and drainage, whilst Vermiculite holds
some water/nutrient and so also helps keep the compost moist and buffer
nutrient levels.




Vermiculite is 'organic'

Http://www.vermiculite.net/

but then Perlite seems to be as well

http://www.vermiculite.net/


I prefer vermiculite as it doesn't leave quite so many gaps in the
medium as Perlite. Perlite doesn't half blow around rather like that
expanded polystyrene packing stuff. Or worse still the insides of the
dogs' bean bags !!
--
Janet Tweedy
Dalmatian Telegraph
http://www.lancedal.demon.co.uk

On Fri, 8 Apr 2005 01:32:20 +0100, "Miss Perspicacia Tick"
wrote:

What's the difference and when should one be used in preference to the
other? As I understand it, both perform the same function - that is to
improve drainage; should the former be used with cuttings and the latter
with more established plants (i.e. if you're repotting)? My father appears
to use them interchangeably but I reckon that, if they could both be used
for identical tasks, then why would they both be sold? I was potting on some
mystery plants (mystery because they were something new I'd bought and I'd
lost the packet and brain fog means I forget my own name sometimes!) and I
didn't know which to use, so I used vermiculite simply because we had more
of it.

So could someone please explain the difference to me (Monty Don only appears
to use vermiculite - I was hoping he'd use perlite for something so I could
fathom it out for myself)?

Thanks

Vermiculite starts life as a relative of mica, which is flash heated
to a few hundred degrees C, when the water bound in the crystal
structure instantly turns to steam and expands the mica-like sheets to
give the result you see. The name comes from the latin 'vermis' - a
worm.

Perlite starts life as a volcanic glass, which is crushed and then
also flash heated but to a rather higher temperature than vermiculite.
The glass softens and water within the glass converts to steam and
foams up the glass. Not sure whether it's an 'open' or a 'closed' foam
structure though, i.e. whether the pores are interconnected and open
to the outside world, or whether they're just a mass of sealed
bubbles.

IME, vermiculite has an alkaline pH. I used to use it in potting mixes
for heathers but didn't understand why the foliage was getting
chlorotic (yellow), until I tested the pH of the vermiculite. I now
only use perlite.

Vermiculite can get quite soggy, but perlite doesn't to nearly the
same extent, so I suppose the argument that it retains moisture better
than perlite is probably true. But I also feel that vermiculite can
inhibit drainage, especially in potted plants, due to the flat platy
nature especially of the larger particles, and after it's been around
for a while. OTOH I am quite happy with the idea that vermiculite
retains nutrients better than perlite, due to what is known as its
'ion exchange capacity', whereas I doubt that perlite has an exchange
capacity of any consequence.


--
Chris

E-mail: christopher[dot]hogg[at]virgin[dot]net

I find perlite is best mixed when mixing your own potting compost potting
compost to aid drainage & use vermiculite to slightly cover my seedlings
instead of compost.

--
Thanks Keith,Nottingham,England,UK.
"Chris Hogg" wrote in message
...
On Fri, 8 Apr 2005 01:32:20 +0100, "Miss Perspicacia Tick"
wrote:

What's the difference and when should one be used in preference to the
other? As I understand it, both perform the same function - that is to
improve drainage; should the former be used with cuttings and the latter
with more established plants (i.e. if you're repotting)? My father
appears
to use them interchangeably but I reckon that, if they could both be used
for identical tasks, then why would they both be sold? I was potting on
some
mystery plants (mystery because they were something new I'd bought and
I'd
lost the packet and brain fog means I forget my own name sometimes!) and
I
didn't know which to use, so I used vermiculite simply because we had
more
of it.

So could someone please explain the difference to me (Monty Don only
appears
to use vermiculite - I was hoping he'd use perlite for something so I
could
fathom it out for myself)?

Thanks

Vermiculite starts life as a relative of mica, which is flash heated
to a few hundred degrees C, when the water bound in the crystal
structure instantly turns to steam and expands the mica-like sheets to
give the result you see. The name comes from the latin 'vermis' - a
worm.

Perlite starts life as a volcanic glass, which is crushed and then
also flash heated but to a rather higher temperature than vermiculite.
The glass softens and water within the glass converts to steam and
foams up the glass. Not sure whether it's an 'open' or a 'closed' foam
structure though, i.e. whether the pores are interconnected and open
to the outside world, or whether they're just a mass of sealed
bubbles.

IME, vermiculite has an alkaline pH. I used to use it in potting mixes
for heathers but didn't understand why the foliage was getting
chlorotic (yellow), until I tested the pH of the vermiculite. I now
only use perlite.

Vermiculite can get quite soggy, but perlite doesn't to nearly the
same extent, so I suppose the argument that it retains moisture better
than perlite is probably true. But I also feel that vermiculite can
inhibit drainage, especially in potted plants, due to the flat platy
nature especially of the larger particles, and after it's been around
for a while. OTOH I am quite happy with the idea that vermiculite
retains nutrients better than perlite, due to what is known as its
'ion exchange capacity', whereas I doubt that perlite has an exchange
capacity of any consequence.


--
Chris

E-mail: christopher[dot]hogg[at]virgin[dot]net

Difficult to pin down when to use perlite and when to use vermiculite,
because I will only use perlite nowadays. Vermiculite is OK inasmuch
as it provides some aeration to the compost, holds on to nutrients and
is water retentive. However, I find it much too water-retentive and
its aerating properties are limited when compared with perlite. It is
far easier for a vermiculite based compost to become soggy and stale.
As to its ability to hold on to nutrients, I tend to use composts
which contain a certain amount of loam, which is far more reactive in
terms of ion-exchange. So no great advantage there.

Used alone, perlite is the better medium for rooting cuttings and
encourages far more vigorous root growth from the outset. The
particle size and shape is such that it promotes faster rooting
compared with vermiculite and being both chemically inert and
pH-neutral, it can be used for all plants. Not so vermiculite.
Perlite is water-retentive to a degree, but does not hold such
quantities as to become completely saturated since its highly porous
nature allow for almost equal amounts of air and moisture to be
retained. Again, the particle shape and size prevent 'panning' within
a compost as it ages. I used to use a small amount of vermiculite to
cover seeds until I discovered that crushed perlite gave better
results.

I suppose its a matter of choice based upon one's own growing
techniques. However, having used both in commercial and domestic
situations, there is no doubt in my mind that perlite is the better
medium .... for me at least.

BTW both are acceptable to the Soil Association and therefore
compatible with organic gardening techniques.

Dave Poole
Torquay, Coastal South Devon UK
Winter min -2°C. Summer max 34°C.
Growing season: March - November

Dave Poole wrote:
Difficult to pin down when to use perlite and when to use vermiculite,
because I will only use perlite nowadays. Vermiculite is OK inasmuch
as it provides some aeration to the compost, holds on to nutrients and
is water retentive. However, I find it much too water-retentive and
its aerating properties are limited when compared with perlite. It is
far easier for a vermiculite based compost to become soggy and stale.
As to its ability to hold on to nutrients, I tend to use composts
which contain a certain amount of loam, which is far more reactive in
terms of ion-exchange. So no great advantage there.

Used alone, perlite is the better medium for rooting cuttings and
encourages far more vigorous root growth from the outset. The
particle size and shape is such that it promotes faster rooting
compared with vermiculite and being both chemically inert and
pH-neutral, it can be used for all plants. Not so vermiculite.
Perlite is water-retentive to a degree, but does not hold such
quantities as to become completely saturated since its highly porous
nature allow for almost equal amounts of air and moisture to be
retained. Again, the particle shape and size prevent 'panning' within
a compost as it ages. I used to use a small amount of vermiculite to
cover seeds until I discovered that crushed perlite gave better
results.

I suppose its a matter of choice based upon one's own growing
techniques. However, having used both in commercial and domestic
situations, there is no doubt in my mind that perlite is the better
medium .... for me at least.

BTW both are acceptable to the Soil Association and therefore
compatible with organic gardening techniques.

Dave Poole
Torquay, Coastal South Devon UK
Winter min -2°C. Summer max 34°C.
Growing season: March - November

Thanks, Dave - I always try to garden organically and biologically whenever
possible. I now consider myself well and truly educated; just didn't want to
be using the wrong thing at the wrong time.

--
In memory of MS MVP Alex Nichol: http://www.dts-l.org/

Janet wrote:

I find that Perlite is good for encouraging rooting on semi hard and
softwood cuttings, but for hard wood cuttings they seem to do better on
gritty, sandy compost. Perlite doesn't seem to encourage them to produce
roots.

Fully agree Janet - I take very few hardwood cuttings nowadays and
therefore forgot to mention that for them, a denser compost seems to
be better. Its down to ensuring that the cut surfaces are in good
contact with compost so that as the sap starts to rise into the buds,
moisture can be easily drawn into the stem.

Dave Poole
Torquay, Coastal South Devon UK
Winter min -2°C. Summer max 34°C.
Growing season: March - November

"Dave Poole" wrote in message
...
Janet wrote:

I find that Perlite is good for encouraging rooting on semi hard and
softwood cuttings, but for hard wood cuttings they seem to do better on
gritty, sandy compost. Perlite doesn't seem to encourage them to produce
roots.

Fully agree Janet - I take very few hardwood cuttings nowadays and
therefore forgot to mention that for them, a denser compost seems to
be better. Its down to ensuring that the cut surfaces are in good
contact with compost so that as the sap starts to rise into the buds,
moisture can be easily drawn into the stem.

Dave Poole
Really pleased someone started this thread as I have been using vermiculite
on seeds with no regard to its PH and shall stop right away! I bought the
bag originally to run some propagating experiments but was not happy with
the results so I thought I would use it up on seed pots. I do use perlite to
loosen up cuttings mixtures so I have it to hand. shows it pays to research
good ideas before going ahead!

--
Charlie, gardening in Cornwall.
http://www.roselandhouse.co.uk
Holders of National Plant Collection of Clematis viticella (cvs)

In article , Dave Poole
writes
Janet wrote:

I find that Perlite is good for encouraging rooting on semi hard and
softwood cuttings, but for hard wood cuttings they seem to do better on
gritty, sandy compost. Perlite doesn't seem to encourage them to produce
roots.

Fully agree Janet - I take very few hardwood cuttings nowadays and
therefore forgot to mention that for them, a denser compost seems to
be better. Its down to ensuring that the cut surfaces are in good
contact with compost so that as the sap starts to rise into the buds,
moisture can be easily drawn into the stem.

Dave Poole


David have you heard of this new RHS advice that you should NOT cut the
tip from a cutting? Normally I would take out the soft tissue at the tip
of the stem but apparently the advice now is to leave it alone because
it's too much shock for the plant's system (apparently)
I assume you still take out any flowering buds if you haven't been able
to choose a cutting without.

janet
--
Janet Tweedy
Dalmatian Telegraph
http://www.lancedal.demon.co.uk

In article , Janet Baraclough
writes
The message
from Dave Poole contains these words:

(snip perlite/vermiculite wisdom)

Thanks for a brilliant and illuminating post which I've printed to keep.

Newer urglers might like to search the group's google archives for
Dave Poole's old posts going back many years; many of which are absolute
gardening classics.

http://groups-beta.google.com/

Janet.





Oh I so agree Janet! Whatever some of the others say I think we are
extremely lucky on this newsgroup to have such a fund of knowledge and
so freely given ad well.

How long before garden-banter assumes it as its own?

Janet
--
Janet Tweedy
Dalmatian Telegraph
http://www.lancedal.demon.co.uk

On Sat, 9 Apr 2005 20:12:42 +0100, Janet Tweedy
wrote:


David have you heard of this new RHS advice that you should NOT cut the
tip from a cutting? Normally I would take out the soft tissue at the tip
of the stem but apparently the advice now is to leave it alone because
it's too much shock for the plant's system (apparently)
I assume you still take out any flowering buds if you haven't been able
to choose a cutting without.

This was something I was taught while training but I've never seen any
gain from removing the soft tips (unless I want another cutting ;~])
so I stopped doing it years ago.

=================================================

Rod

Weed my email address to reply.
http://website.lineone.net/~rodcraddock/index.html

Rod wrote:

David have you heard of this new RHS advice that you should NOT cut the
tip from a cutting?

This was something I was taught while training but I've never seen any
gain from removing the soft tips (unless I want another cutting ;~])

I rarely pinch out the tips until the cuttings have rooted, but must
say that having taken many hundreds of thousands of cuttings over the
years, I've never noticed any 'shock' as a result of removing the
growing tips. As an unscientific experiment some years ago, I did
trays of lavender, phlladelphus and fuchsia - two for each type, one
with the shoot tips and one without. They were given identical
conditions (well, for the relevant plant type) and rooting took place
more or less simultaneously.

Dave Poole
Torquay, Coastal South Devon UK
Winter min -2°C. Summer max 34°C.
Growing season: March - November