The Term Harden off

[Shawna]

Some of the orchids i grow i have read that after the Pseudobulbs have matured to let them harden off. Does that mean withhold watering or what is the meaning of harden off?

[Roberta]

What type of orchid did this refer to? I have head the term applied to Cattleya flowers... when they first open, they may somewhat flop. The temptation when they first open is to bring them inside right away, but the flowers are likely to present better and last longer, if they stay out in nature a little longer - the flower stems become harder. Maybe someone has a different approach, but my interpretation of the term generally is, that when it looks like it is ready to do something, leave it alone for a bit longer if it is your intention to change something in its environment.

[Ray]

To me, “hardening off” refers to getting the plant tissues stabilized in the current environment. If anything, it means pampering the plant while it gets there, not withholding anything. One exception might be reducing nitrogen application.

Newly grown plant tissues are soft and supple, and quite exposed to pathogens and “the elements”. Over time, they will develop waxy cuticle layers that protect the tissues, which also makes them a bit firmer.

In the case of newly deflasked seedlings, they have been living in a sterile, stable environment, so will need to adjust, especially to fluctuating humidity levels, and that process is also called “hardening off”.

[Shawna]

I can't really remember specifics right now but i think it was in the cattleya family right before they flower or so that it would aid in producing flowers besides the temperature drop. Also after catasetum plants have finished flowering. Maybe just giving more direct sunlight at a certain time. I can't seem to find the articles i was reading about it.