cactus

[periwinkle]

i went away and my mum thought it would be a could idea to put my cactuses outside some of the mamillaria ones have got yellow spots any ideas?
thnx

[jonukas]

It could possibly be sunburn, if the sun is very hot after a shower, the raindrops act like little magnifying glasses.
If you are ever going away again don't worry about your cacti, just water them before you go and they will be fine for a fortnight, you 'll be surprised how long they can survive without water, don't forget, they are desert plants and in their natural habitat they can go a hell of a long time without water. In winter my cacti get NO water from October till March without any ill effects, if you do water through Winter it can cause rot. Good luck, Jonukas