Seedlings - a nice shade of red

[Duns]

I have a tray of mixed cacti seedlings that were sown in September 2017 and kept on a windowsill in the house. When I got my new propagator and 2 led grow lights I moved them into the greenhouse (heated to 3 - 5C) placed in the propagator (set to 20C) with lights set to operate from 6am to 8pm.

They have now turned a pinky/red colour which I presume is due to insufficient light and, or, temperature. Is there an hope for recovery once conditions are improved or are they a lost cause?

Any advice would be gratefully received.

John

[habanerocat]

Not a lost cause.

Have a read of the BCSS see raising leaflet. Pages are a bit mixed up.

http://www.society.bcss.org.uk/images/C ... atemix.pdf

Red is often a sign of stress, perhaps in your case too much light. I'd also consider dropping the temperature a few degrees. From now on it may start getting very hot inside the propogator. You'll need to keep a close watch.

[Duns]

Many thanks Habanerocat - I will reduce propagator temperature and reduce the grow lamp duration and see if that helps.

John

[MikeT]

Red colour is not due to too little light. Too strong sunlight could turn the plants red, but propagator lights (plus January sunlight) shouldn't be a problem. At propagator temperatures, the seedlings will want plenty of water - the red colour may be stress from being too dry at those temperatures. Keep going with the propagator but keep the seedlings well watered.

[Duns]

Thanks Mike - will do.

John

[iann]

Propagator lights, depending on strength, can certainly turn cactus seedlings red. Red is certainly from some sort of stress, but usually high light or low temperatures rather than just lack of water. 3-5C is pretty chilly for most cactus seedlings and would contribute to the colour. 20C is also not particularly warm and they'd probably grow better a bit warmer.

Slightly reddish colouring, which tends to appear brown in combination with the natural green, is not a problem. Bright red, scarlet, and shading to pink, is too much and you should try to reduce the stress that is causing it. No reason for it to be immediately fatal, but longterm it is asking for trouble. Growth has probably been set back and might have to be patient for them to get moving again. Colouring varies between species, but generally a dark green shading to a slight reddish tinge is good. Some species stubbornly refuse to go red even when stressed, others go quite strong red in very modest light. Some of the densely-spined Mammillarias go red and there's very little you can do to stop it until they grow a good covering of their own:

[Duns]

Thank you very much Iann for your advice and associated explanation - very helpful.

Combined with the advice from Habanerocat and Mike my plan is formulated

1 Reduce lighting - the propagator is in a position of good light in the greenhouse.

2 Increase propagator temperature to say 23C

3 Check moisture every day and water as necessary.

Thank you all once more.

John