"Wylie Wilde" wrote ...
I live in Melbourne which experiences mild winters- hardly any frost in the
suburbs. But the summers are a scorcher- and we experience 40C days- and
the average temperature for the week can be 30C+. thats what? about 111F-
120F?

We're experiencing Summer right now- if you want to visit- I wouldn't
advice it- its way too freaking hot!!!!!

Some of the Dahilas have been scorched by the heat and the leaves have
turned burnt.

They are in an exposed part of the garden - facing the west and get 8+
hours of hot sun.

(Sometime in the future- when i have the time and "family" political
power- I will plant some trees in the front nature strip to block the hot
sun)

Sorry to bump into the uk gardening section- like this. I posted similar
messages in rec.gardens and aus.gardens but got little response.


I suspect your problem is water, or lack of enough to keep up with the
plants transpiration (sweat). Besides the heat, you also have that strong
Melbourne sun which is stronger than our hottest summer sun even in the
shade. :-)
If you really must grow dahlias then you need to tackle both these things.
They need to be out of your direct sun, especially in the middle of the day,
that's an open aspect but in just no direct sun. You will also need to take
care with the watering to make sure they have enough. Is the soil water
retentive or easily drained (sandy)?
Shade from trees might not improve matters as the trees would take up water
too and make that problem worse.

There are shade cloths about too which you can use to good effect by
building a pergola over the plants and covering it with the shade cloth.
Comes in different shade %'s.

--
Regards
Bob
In Runnymede, 17 miles West of London