Sunburn questions

[Tree]

Hi, With summer approaching I have some questions regarding cactus sunburn :confused: :

1)After being slowly adapted, what would be the most sunlight you would expect the following cactus to handle:

T. pach, T. scope, T bri and L. will

2)What would be ideal sunlight for these?

3).Apart from the cactus type, is age, size, or both a factor to adapting to the sun?

4).How does grafting effect the resistance to sunburn for a Loph?

-Would a grafted pup be any more or less resistant soon after grafting?

-How would a couple of pups that are the same age compare, where one was grafted for a year and the other just rooted?

5).How do cactus seedlings and pups cope with sunburn in the wild?

Your comments are much appreciated

Thanks

[Stonehenge]

I would like to hear an answer myself because I'm not sure my results are the same as everybody elses. I find that t pach can take full sun all day and so can t bridge and t peru. Lopho can take it but mine never got used to the sun. I've seen others that did but not mine. My hoodia love the sun. The pups on plants outdoors do just fine. The main thing is if you have an indoor plant it has to adjust to the outside over a period of 1 to 2 weeks or you will have burn.

Stoney

[t st tantra]

my loph did not handle full sun well at all,but it has grown really well under 50% shade cloth with very little direct sun.

my trichs sit in full sun up to 43C with no problems,if you have problems your plant is probably not healthy.

seedlings are best out of full sun and when large enough introduce them to sun under a partly shading plant for a couple weeks.i dont yet know what size is best for that.

t s t .

[gerbil]

loph. seedlings seem to be very sensitive to bright light, have some 36w fluro tubes about 5-10cm from the top of a yates humidity dome (which has paper on it to filter light) and just a tiny bit of direct light got through and burnt the seedling. Yet Trichocereus seedlings haven't shown any signs of burning even when they did recieve some direct light.

What i'll be doing for summer, is covering the inside of those humidity domes with a dark fly screen, and put it in partial sun, then gently ween them off. My guess will be heavily filtered light, say 20-30%?

5).How do cactus seedlings and pups cope with sunburn in the wild?

My guess is that if they germinate in an area where they will get badly burnt, they wouldn't survive well, if at all. But i'm no expert on wild cacti.

[ 20. September 2003, 17:52: Message edited by: gerbil ]

[Tree]

Thanks for your replies - Good info:)

A couple more Qustions:

a)How quickly does a cactus burn appear?

b)Do you need to cover cacti up during a random heatwave. eg where daily temps are over 40deg for a few days?

Thanks again, take care.