V_coerulea wrote:
I seem to have a little problem with potinaras, some slc's and Blc Oconee
and where Oconee is a direct parent. I get burning on the leaves
particularly any new growth in anything less than 20% shade. I leave up 20%
shade over a 20X20' section of the greenhouse during winter. That section
increases to 60% in mid-summer, some gets 40% and the rest is 20% at that
time. Most of my catts get full light in the morning and 20% shade from noon
on at this time of year. Most species are in full sun. As I increase shade
the above mentionned hybrids seem to have less problem with leaf burn. I
live below 33o latitude in the southern US where the sun is strong even at
this time of the year. I guess my main question is: Are these hybrids that
sun sensitive everywhere? Should I look for just that right spot or forget
growing them here? Thanks for your input.
Gary

Look for the right spot. If you are growing in a greenhouse during the
summer, remember that the roof will filter 10% or more of the light.
Adding a 60% shade cloth will reduce the available light to only about
30%. If you increase the light intensity during the summer (reduce the
shade density) and match the orientation of the plant, you should
actually need very little shade during the winter. I have a
translucent insulation in the roof, but no shade on the windows for my
catt hybrids during the winter in Missouri.

I move mine outside the first week of May. The sun starts out with a
more southerly orientation, and lower in the sky. By midsummer it gets
intense. While they are under trees, they get no shade until after 10
a.m. in midsummer, some don't get any shade for another hour. They are
shaded by the trees for 3 to 4 hours, then get afternoon sun. When
they are acclimated to the higher light levels, they don't burn, unless
I change their orientation to the sun or move a plant that may be
shading a portion of the leaf (bikini burn).

I will tell you, it is not easy to acclimate a mature plant to those
conditions. Most of my plants were purchased as small seedlings and
have always lived under bright condition. Their growth is lighter and
firmer than most mature plants I have purchased. Hybrids bought as
mature plants will sunburn and bear careful watching. I put them on
the most protected end of the tables. When the new growth develops
under brighter light, they handle the increased intensity much better
than the old growth. But they may look rough for 2 or 3 years, while
the plant is growing under the brighter light.

Not sure where "here" is exactly in your case. The intensity of the
sunlight will vary with the altitude, humidity, and cloud cover.

Happy growing, Nancy