Direct Light, Indirect Light, etc

7 years ago

Tis the season for moving plants back outdoors and gradually acclimating them from indirect to more direct lighting. (Well not quite time for me yet actually, average last frost here is mid-May.) Anyway, I have found that the terminology for outdoor lighting is somewhat un-intuitive so I am working on making a table of lighting conditions to understand them better and would appreciate some help filling it in. What I have done is just listed a series of terms I have read through my research and if you can help provide a definition to fill in the blanks that would be great! (A generic example would also be helpful.) My hope/goal is that this will eventually become a useful guide for other beginners like me so I have taken the liberty to include some general advice I have read in other posts as well.

First a Quick Question

Can you begin acclimating plants earlier in the season when there is still a frost risk by bringing them back inside at night? Or is it generally a better practice that once the plant goes out it stays out?

Lighting Conditions

(Please feel free to add any others you can think of and I'll work on figuring out the forum's edit feature to add them to the list!)

  • Direct Light: I think I have this one pretty well covered--sunlight is directly hitting (lighting up) the leaves of the plant - or - to think about it differently, the plant is casting a shadow. (Example: A plant in the middle of a wide open field.)

Indirect Light: At the most basic level, this is light that does not directly hit the plant (kind of a circular definition if you ask me). What this really means is light that is reflected onto the plant, say from the ground or a wall. Imagine being in a dark room and shining a flashlight on the wall at an angle. There will be a very bright region (direct light) and not so bright regions on the periphery (indirect light). Some of the light may even reflect onto the ceiling. (Example: A plant against a North facing wall where the light is reflected off the ground or an opposite wall. Another example: Light from the Moon.)
Bright Indirect Light: Without fancy analytical devices, it is difficult to determine light intensity. A bit of a shortcut is that bright light will create sharp shadows, while dull light creates fuzzy shadows. (Still working on this one.)
Filtered/Dappled Light: This is kind of a transient lighting condition created using leaves, mesh screens, windows, shade cloths, etc. Generally plants in this condition are considered to have indirect light even though direct light may strike the plants (through gaps in the canopy or between the wire grid of a mesh screen). I think the basic idea is that as the day progresses or the wind blows, the time a specific part of the plant receives direct light is minimized such that the plant as a whole is indirectly lit.
Shade: Shade seems synonymous with...

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