When do you start sun hardening seedlings

[Zedo]

To everyone who sent me seeds this year... and cacti. Thankyou. 

 

The seedling are going great great in my little green house but I'm unsure when to take them out and let them enjoy the sun. I don't want them to die.

 

so their about 5-8mm in height. When should I do what? 

 

First pic is the seedlings..well some. And the second is the cacti I got from 3 terrific individuals in front of the Hopi blue corn which is going strong too. 

 

 

[bardo]

This is only my third year of growing cacti from seed, my second year was quite successful so i have taken it up a notch this year, must be at least a thousand of them, Most definitely not a pro and never use lights (i hate coal power electricity and have limited solar)

Man just slowly open the tubs or what not, slowly bring them to full open conditions, i usually start with a chinese container than pot them up into small pots in a plastic tub then slowly open it, once no lid is on them and looking fine i bring them into brighter conditions, i am still a little worried and go the cautious path, tho some i exposed to full open conditions earlier are some of my biggest and strongest cacti, trial and error for your region. I have been potting them out of the chinese containers after about 12 months from sowing, is this the right thing to do or not i don't know tho i have been pretty successful so far, just don't worry to much cause there is plenty of seed available to enthusiast such as us. I start them under shade cloth and they get about 3 hours of direct light a day.

As a side note i am listening to Paul McCartney Ram, shit that's a good cd, a little satanic but enjoyable to listen to all the same : )

[Zedo]

Yeah I was leaning towards just taking them out for a small amount of time each day and extending the period, but was sorta worried too much movement may not be good. 

[nrivers]

I have just learnt from trial and error mate. They are pretty forgiving and usually tell you if you are doing something wrong

[Trevyn]

Does some time on a graft make it safer to put in full sun (more water uptake and size) or is it more a time based thing?

[Spanishfly]

when they start looking like miniatures of the adult - and not blobs of green jelly.

[Change]

I prefer not to expose seedlings to full sun untill they are the size of the smallest 2 in your second picture. Generally speaking i do this in winter so they can adjust when the sun isnt so strong.

 

6 hours ago, Trevyn said:

Does some time on a graft make it safer to put in full sun (more water uptake and size) or is it more a time based thing?

 

That depends on if the graft is growing in full sun or shade. The key is minimizing the shock by not exposing them to condition that will stall there progress. 

As Nrivers has said, they are really forgiving, If you move them into full sun to fast and they burn, youll see the damage and have plenty of time to move them back into shade. 

Because cactus use C4 photosynthesis they dont have major issues with loosing water via transpiration like C3 plants do. I think the major factor is progressivly increasing the plants exposure to UV rays so they dont burn. This is why i do it in winter, rather than trying to move the cactus around to increase there exposure i let the sun and seasons do the work for me.