hi all I have germinated some trich's, loph's & soon to be ario's and pelecyphora and I just want some advice on how long they should be left with lid on after germination? (I am using takeaway containers)
I have done some research but I find a lot of the information conflicting, how long can they (various species) last in the takeaway containers?
one of my containers has developed a slight green algae (its pretty minimal but its there) I am using washed and sterilized prop sand...

some advice would be greatly appreciated

I have been told they can be left in zipper bags for 12 months.

I guess it all depends on fungi etc. I wonder if you took the lid off for a day to let it dry out a little if it would stop the algae growth.

depends on how fast they are developing. the Trichocereus are doubtless going to grow alot faster than the pelecyphoras, arios and lophs you have for example, and can be weaned off the high humidity a lot faster. in fact its probably beneficial to prevent them becoming elongated and leggy in the monsoonal conditions. basically it is important to maintain high humidity and to prevent drying out in the initial stages of development, after which you gradually reduce the humidity and ultimately acclimatise the seedlings to normal air conditions.

I have ario retusus and fissuratus seedlings that have been covered for 3 months+ now. they are starting to develop tubercles but are still tiny.
i kept seedling Epithelantha micromeris covered for more than 5 months, gradually poking a few holes in the plastic, then a few more in the weeks to come and so on and so on and now they grow under normal air conditions, but still in the propagator.

I have heard Blossfeldias can last covered for 2 years as they as so tiny.
i never worried about the algae, as soon as you reduce the humidity it disappears, although a problem with this i have heard is when you grow Aztekiums and blossfeldias which actually grow slower than algae and and is resultingly smothers the seedlings.

This should be in the propagation forum, I would move it but I don't think I can.

San Ranbow,

I think the source of your confusion is due to different climatic conditions. Each article you read or persons personal exprience is specific to their location. The length of time the seedlings need to be kept in high humidity will depend on the species and to a lesser degree sub species. The temperature range, humidity, air pressure, light intensity and even uv exposure will all contribute to the time required. To give an exact time is impossible due to this.

The green growth you speak of is harmless provided it grows slower than the cacti. If the growth become as tall as the cacti it will begin to compete for nutrients and more importantly light. As betty said above by removing the lid and allowing the surface to dry every now and then, helps prevent it building up.