|
Home > Archive > UK gardening > June 2005 > Light levels and plants
You are viewing an archived Text-only version of the thread.
To view this thread in it's original format and/or if you want to reply to
this thread please [click here]
| Author |
Light levels and plants
|
|
| Alla Bezroutchko 2005-06-26, 6:25 pm |
| I seem to be confused about the terms describing light levels. Perhaps
someone can help me with that? The generally used terms are "full sun",
"partial shade" and "full shade". I thought that "full sun" means that
the plant receives direct sunlight for the whole day, "full shade" means
that the plant gets no direct sunlight, and "partial shade" is
everything in between.
Do I misunderstand it? My camellias that are supposed to be okay in
partial shade got sunburned, and lavender, which is supposed to require
full sun, is thriving even though it does not get any direct sunlight in
the afternoon. What am I missing?
BTW, will heathers like a place that gets direct sunlight in the morning
and is shaded by a hedge in the afternoon?
Alla.
| |
| Nick Maclaren 2005-06-26, 6:25 pm |
| In article <42bee91e$0$345$ba620e4c@news.skynet.be>,
Alla Bezroutchko <alla@scanit.be> wrote:
quote:
>I seem to be confused about the terms describing light levels. Perhaps
>someone can help me with that? The generally used terms are "full sun",
>"partial shade" and "full shade". I thought that "full sun" means that
>the plant receives direct sunlight for the whole day, "full shade" means
>that the plant gets no direct sunlight, and "partial shade" is
>everything in between.
Pretty well, yes.
quote:
>Do I misunderstand it? My camellias that are supposed to be okay in
>partial shade got sunburned, and lavender, which is supposed to require
>full sun, is thriving even though it does not get any direct sunlight in
>the afternoon. What am I missing?
That plants that dislike hot, sunny conditions can suffer from
'sunburn' even in full shade. I was out of the country during
the hot spell (have I missed summer?) but it sounds as if that was
enough to do it.
My Tropaeolum speciosum in partial shade was doing much better than
those in full shade, but the past week turned it chlorotic whereas
the others have not changed colour. It would doubtless recover
unless we go back to those conditions.
quote:
>BTW, will heathers like a place that gets direct sunlight in the morning
>and is shaded by a hedge in the afternoon?
Many heathers will take all the sun that this country ever gets, and
more. Others will dislike hot conditions. That sounds fine.
Note that, except on very rare days (a few days every few years),
the sun in the UK never approaches the intensity of even places like
the Mediterranean and the USA, let alone the high-altitude, dry
tropics.
Regards,
Nick Maclaren.
| |
|
| In article <42bee91e$0$345$ba620e4c@news.skynet.be>, Alla Bezroutchko
<alla@scanit.be> writes
quote:
>I seem to be confused about the terms describing light levels. Perhaps
>someone can help me with that? The generally used terms are "full sun",
>"partial shade" and "full shade". I thought that "full sun" means that
>the plant receives direct sunlight for the whole day, "full shade" means
>that the plant gets no direct sunlight, and "partial shade" is
>everything in between.
>
>Do I misunderstand it? My camellias that are supposed to be okay in
>partial shade got sunburned, and lavender, which is supposed to require
>full sun, is thriving even though it does not get any direct sunlight in
>the afternoon. What am I missing?
Partial shade is often used to mean the dappled shade caused by a
lightly foliaged tree like a birch - in other words, not full sunshine,
but filtered sunshine most of the day - this is more what the camellia
would like, not full sun for part of the day.
quote:
>
--
Kay
"Do not insult the crocodile until you have crossed the river"
| |
| Hazel 2005-06-26, 11:25 pm |
|
"Alla Bezroutchko" <alla@scanit.be> wrote in message
news:42bee91e$0$345$ba620e4c@news.skynet.be...
quote:
>I seem to be confused about the terms describing light levels. Perhaps
>someone can help me with that? The generally used terms are "full sun",
>"partial shade" and "full shade". I thought that "full sun" means that the
>plant receives direct sunlight for the whole day, "full shade" means that
>the plant gets no direct sunlight, and "partial shade" is everything in
>between.
>
> Do I misunderstand it? My camellias that are supposed to be okay in
> partial shade got sunburned,
Am I not correct in thinking camellias should not be subjected to the
morning sun, perhaps this is why they got burned ?
Hazel
| |
| Nick Maclaren 2005-06-27, 12:25 pm |
| In article <4GGve.4084$ZR1.2799@newsfe2-gui.ntli.net>,
Hazel <ann@garbage.net> wrote:
quote:
>
>
>Am I not correct in thinking camellias should not be subjected to the
>morning sun, perhaps this is why they got burned ?
That is a different effect. Camellias can take some frost, but sun
on frozen material will often kill it - and camellia buds are quite
sensitive to frost.
Regards,
Nick Maclaren.
| |
| Alla Bezroutchko 2005-06-27, 12:25 pm |
| Kay wrote:
quote:
> Partial shade is often used to mean the dappled shade caused by a
> lightly foliaged tree like a birch - in other words, not full sunshine,
> but filtered sunshine most of the day - this is more what the camellia
> would like, not full sun for part of the day.
I don't have much dappled shade, but I have a lot of space that gets
sunshine part of the day and is shaded for the rest of the day, some in
the morning, some in the afternoon. So what should I plant, shade
tolerant or sun loving things?
Alla.
| |
| Nick Maclaren 2005-06-27, 12:25 pm |
|
In article <42bfabf3$0$334$ba620e4c@news.skynet.be>,
Alla Bezroutchko <alla@scanit.be> writes:
|>
|> I don't have much dappled shade, but I have a lot of space that gets
|> sunshine part of the day and is shaded for the rest of the day, some in
|> the morning, some in the afternoon. So what should I plant, shade
|> tolerant or sun loving things?
Most plants that thrive in the UK are shade tolerant - they have
to be! Don't plant true sun lovers, because they won't thrive
(and some can't handle the UK's dim light at all), but there are
relatively few of those commonly grown in the UK. Similarly,
there are few plants that can't handle UK sunlight (or that in
Belgium), but some will burn slightly once every few years.
Note that there are far more that will suffer from drought or
waterlogging.
Regards,
Nick Maclaren.
| |
| Alla Bezroutchko 2005-06-27, 12:25 pm |
| Nick Maclaren wrote:
quote:
> Most plants that thrive in the UK are shade tolerant - they have
> to be! Don't plant true sun lovers, because they won't thrive
> (and some can't handle the UK's dim light at all), but there are
> relatively few of those commonly grown in the UK. Similarly,
> there are few plants that can't handle UK sunlight (or that in
> Belgium), but some will burn slightly once every few years.
Thanks to everyone who tried to enlighten me. I guess I will just try
planting things best I can and see what will grow and what won't.
Alla.
| |
| Chris Hogg 2005-06-27, 6:25 pm |
| On 27 Jun 2005 07:05:17 GMT, nmm1@cus.cam.ac.uk (Nick Maclaren) wrote:
quote:
>In article <4GGve.4084$ZR1.2799@newsfe2-gui.ntli.net>,
>Hazel <ann@garbage.net> wrote:
>
>That is a different effect. Camellias can take some frost, but sun
>on frozen material will often kill it - and camellia buds are quite
>sensitive to frost.
>
>
>Regards,
>Nick Maclaren.
I've seen this said too often for it to be a myth, but what's the
explanation? My understanding of frost damage is that ice crystals
within the cells expand as they form (as does all ice), so rupturing
the cell and killing it. But why should sunshine on frozen foliage
cause damage? Surely the damage is done by the freezing process, not
the thawing. And I don't buy the suggestion that the ice crystals on
the leaves concentrate the sun's rays in some way, producing scorch,
unless someone can cite some well-documented and reliable research
that proves it.
--
Chris
E-mail: christopher[dot]hogg[at]virgin[dot]net
| |
|
|
quote:
> Thanks to everyone who tried to enlighten me. I guess I will just try
> planting things best I can and see what will grow and what won't.
>
> Alla.
I would agree with that, work with nature and the conditions you have, not
against it.
Hazel
| |
| Nick Maclaren 2005-06-27, 6:25 pm |
| In article <vng0c1t6ctuse3naoj3vv263uqeb1dg0gr@4ax.com>,
Chris Hogg <me@privacy.net> wrote:
quote:
>
>I've seen this said too often for it to be a myth, but what's the
>explanation? My understanding of frost damage is that ice crystals
>within the cells expand as they form (as does all ice), so rupturing
>the cell and killing it. But why should sunshine on frozen foliage
>cause damage? Surely the damage is done by the freezing process, not
>the thawing. And I don't buy the suggestion that the ice crystals on
>the leaves concentrate the sun's rays in some way, producing scorch,
>unless someone can cite some well-documented and reliable research
>that proves it.
The 'best' explanation that I heard was that it is actually heat
damage :-)
Because the water is fixed, it is not available for cooling the
cell walls (by convection, evaporation or otherwise) and so they
overheat and are damaged that way. I neither believe nor disbelieve
this explanation. But, if it is not true, it is well-argued, and I
cannot think of another one.
Yours in perplexity.
Regards,
Nick Maclaren.
| |
| Janet Baraclough 2005-06-27, 11:25 pm |
| The message <vng0c1t6ctuse3naoj3vv263uqeb1dg0gr@4ax.com>
from Chris Hogg <me@privacy.net> contains these words:
quote:
> On 27 Jun 2005 07:05:17 GMT, nmm1@cus.cam.ac.uk (Nick Maclaren) wrote:
quote:
[vbcol=seagreen]
> I've seen this said too often for it to be a myth, but what's the
> explanation?
Surely it's only cammelia's flowers/flower buds that are spoiled by a
combination of sun on frost? Not the roots/stems/leaves.
Janet.
| |
| Dave Poole 2005-06-28, 6:25 pm |
| Janet Baraclough wrote:
quote:
> Surely it's only cammelia's flowers/flower buds that are spoiled by a
>combination of sun on frost? Not the roots/stems/leaves.
Quite right, it is extremely rare for a Camellia's foliage to be
damaged by sun *unless* it is dry at the root. The old
recommendations were to grow them close to west facing walls, which
helped protect the expanding buds and yet allowed the plants to get
sun later in the day. These hold as true today as they did 50 years
ago. Exposure to early morning sun in winter and early spring damages
the flowers and expanding buds only. Dappled or light shade isn't
essential and given sufficient moisture, Camellias grow very happily
exposed to full sun in the UK at least. In fact, if you can arrange
for the plant to get full sun at all times except during winter and
early spring mornings, you can be sure of a magnificent flowering
virtually every year.
Dave Poole
Torquay, Coastal South Devon UK
Winter min -2°C. Summer max 34°C.
Growing season: March - November
| |
| Chris Hogg 2005-06-28, 6:25 pm |
| On Mon, 27 Jun 2005 20:53:28 +0100, Janet Baraclough
<janet.and.john@zetnet.co.uk> wrote:
quote:
>The message <vng0c1t6ctuse3naoj3vv263uqeb1dg0gr@4ax.com>
>from Chris Hogg <me@privacy.net> contains these words:
>
>
>
>
> Surely it's only cammelia's flowers/flower buds that are spoiled by a
>combination of sun on frost? Not the roots/stems/leaves.
>
> Janet.
Yes you're right, but my query still stands. For leaves read petals.
--
Chris
E-mail: christopher[dot]hogg[at]virgin[dot]net
| |
| Mike Lyle 2005-06-28, 6:25 pm |
| Chris Hogg wrote:
quote:
> On Mon, 27 Jun 2005 20:53:28 +0100, Janet Baraclough
> <janet.and.john@zetnet.co.uk> wrote:
>
to[vbcol=seagreen]
sun[vbcol=seagreen]
quite[vbcol=seagreen]
>
> Yes you're right, but my query still stands. For leaves read
petals.
When the buds get frozen during the night, direct sun thaws them too
quickly, and the cells bust.
--
Mike.
| |
| Nick Maclaren 2005-06-28, 6:25 pm |
| In article <3idgt9Fkvs0qU1@individual.net>,
Mike Lyle <mike_lyle_uk@REMOVETHISyahoo.co.uk> wrote:
quote:
>Chris Hogg wrote:
>petals.
>
>When the buds get frozen during the night, direct sun thaws them too
>quickly, and the cells bust.
I am unable to match that to any of the physics, chemistry or biology
that I know - while that may be due to my ignorance, it also may be
that the explanation you have just given is erroneous. I can certainly
witness that it is the commonly supplied one, but that does not make
it correct.
Regards,
Nick Maclaren.
| |
| Mike Lyle 2005-06-28, 11:25 pm |
| Nick Maclaren wrote:
quote:
> In article <3idgt9Fkvs0qU1@individual.net>,
> Mike Lyle <mike_lyle_uk@REMOVETHISyahoo.co.uk> wrote:
petals.[vbcol=seagreen]
too[vbcol=seagreen]
>
> I am unable to match that to any of the physics, chemistry or
biology
quote:
> that I know - while that may be due to my ignorance, it also may be
> that the explanation you have just given is erroneous. I can
> certainly witness that it is the commonly supplied one, but that
does
quote:
> not make it correct.
OK, I couldn't derive a theoretical basis, especially since water
expands as it freezes -- I toyed with the idea that maybe water
migrating out of the cells gradually might be less damaging than a
sudden rush for some reason I couldn't fathom. So what _does_ cause
it? Is it about freeze-drying?
--
Mike.
| |
| Nick Maclaren 2005-06-28, 11:25 pm |
| In article <3idrkiFku44rU1@individual.net>,
Mike Lyle <mike_lyle_uk@REMOVETHISyahoo.co.uk> wrote:
quote:
>
>OK, I couldn't derive a theoretical basis, especially since water
>expands as it freezes -- I toyed with the idea that maybe water
>migrating out of the cells gradually might be less damaging than a
>sudden rush for some reason I couldn't fathom. So what _does_ cause
>it? Is it about freeze-drying?
I posted a possible explanation earlier, but I am unconvinced by it.
I think that it may be a freeze-drying phenomenon, of sorts, but
really don't know.
Regards,
Nick Maclaren.
|
|
|
|
|