A sheer curtain over the blinds could help. I don't think the moving of the blind slats makes all that much difference, but that's my opinion.

The way to tell low light versus medium/high is:

Get a piece of white paper. If you seen no distinct shadow, that is low light. If you can make out a shadow, but the shadow is not sharp/crisp, that is medium light. A sharp distinct shadow is high light.

I don't have much experience with cacti since my east and west windows don't get the sun required for them, but the south window should be great, I would think. I'll let others weigh in. That's weird that your aloe plant didn't like it.

To clarify: place your hand over the white paper as you test the light in various locations of the room. Sorry, I left that part out.

Found with Google search, hope this helps.

What is a sunny (direct sun) location?

• Within 2 feet of a south- or southwest-facing window.
• Window sills flooded with sunlight.
• A sun room (If you have one, lucky you!)

What is a bright (indirect sun) location?

• Within 4-5 feet of an east- or west-facing window.
• 3-5 feet from a window that faces south or southwest.
• Any place where the sun shines into a room for several hours.

What is a partially shaded (low light) location?

• An east-facing window where the morning sun shines into the room for only a few hours. Morning sun is cooler than afternoon sun, so you don't have to worry about overheating your plant.
• At least 3-5 feet away from a window that faces south or southwest.
• Directly in front of a north-facing window gives a plant low-to-medium light intensity.

What is a shady location?

• More than 6 feet away from a south- or southwest-facing window.
• Hallways, staircases, and corners of rooms.
• Near windows that are shaded by trees.

Just to add this, if you can read by the light it will be OK for low light plants. ZZ plants do better in bright light. Sun burning is usually caused by placing a plant unaccustomed to direct sun into direct sun with out acclimatization ( for plants that will take full sun that is). If you could move your plants back from the window sill that would help some too. Sheer curtains as mentioned above are a way to cut down on the bright sun shine.

Make note of where the sun light is at the varying times of day, then you can figure which plant to put where according to their preferences.

thanks guys. I live in Ontario Canada. its just all this mumble jumble of lighting and plants is very complicated. when they say a plant needs low medium or high light... how does one define medium light accurately? I know most foliage plants u buy...dracaenas, pothos, ivy, philos, spaths, sans, zz, parlor palm, bamboo palm, dwarf scheffs, even coffee nana the list goes on with common indoor plants all need medium light. now ive been using a light meter on my cell phone walking around inside my living room at various spots away from windows like the interior of my living room where I wanna decorate with indoor plants the most rather then clutter my south-south west window sills of plants.. ive read on many websites if I go by foot-candles (which my phone light meter does) then medium light as a rule is approx. 75-150 ish foot-candles for more then a few hours daily...mind u early in the day and later in the day as the sun sets or rises one wont have 75-150 FC reading lol. but yea many of my spots in the interior of my room have readings from 75-150FC and as stated by many websites that's approx. medium light. even tho the interior locations in my apartment look dark to me..human eyes don't judge light good at all as we see different light then plants do.. even tho the interior locations look dark when I use my phones light meter I get readings of around 80-150 FC sometimes a lil higher! so im guessing if my light meter in a "dark" area still reads a higher FC like 80-150 ish reading I can go ahead and put a medium light plant there and save my hot blazing sunny window sills for amaryllis soon in stores, and my cacti, and my aloe, and my date palm seedlings and my lemon tree seedlings and my mango tree seedling im gonna start lol free plants r the best lol

jay83, I agree with your mumble jumble comment. Measuring light intensity indoors (read as my SE exposure apartment) depends on many factors such as time of day, angle of sun, cloudy, overcast or clear skies, season of the year, foliage on or off trees, even the walls (flat or eggshell paint absorbs light while my satin finish bathroom wallpaper reflects it). Guidelines are just that - guidelines. Let the plants be your guide, observe their growth habits, make corrections when needed, but most importantly, enjoy them.

jay83, I just reread your opening post about being in a basement apartment with a SSW exposure. I am on the 5th floor of a high-rise, 63" vertical windows, SE exposure. NY capitol region, no interference from trees or other structures. Location makes a difference. To quote my Grandmother, "if they're healthy and growing where they are, then they're happy".

Jay - I have two light meters that I use determine light levels around my home and outside. I also live in Ontario.

Foot-candles/typical lux meters are a helpful tool, but only tell a small part of the story. They give an instantaneous reading only that is helpful for human vision. I'm also unsure of the accuracy of your phone's light sensor (my lux meter is designed for that purpose).

What you really need is a meter that reads PAR (wavelengths of light that plants use) with DLI (how much light is received in a whole day). I use mine very frequently.

Low/medium/high light is a generic range that gives just a starting point. Each plant light requirements is relatively unique but obviously enveloped by what that species generally requires.

Given what you currently have, here is what I would describe, provided this amount of light is given for most the day:

2000-4000 fc = full sun

1000-2000 fc = partial sun

400-1000 fc = partial shade to bright shade

100-400 fc = shade

0-100 fc = full shade

Of course, a spot could be extremely bright for part of the day, but that doesn't count as a full sun location.

Here are two graphs of essentially equivalent light (nearly full sun) in DLI outdoors on my roof vs indoors with a timer:

X axis is hours, Y axis is PAR DLI (logrithamic).

Of course, even with light readings you still need to watch the plants closely and adjust accordingly.

Light meters are powerful and very helpful tools, just not used that effectively (or understood well) outside of professional greenhouses.

Just get your plants accustomed to the light by gradually moving them closer every few weeks. When you buy a new plant, put it away from direct sunlight. Leave it there for a month. Gradually move it closer and closer to the window. But you need to do this very gradually. The leaves on your plant grew with the light they were getting at the time they grew. The newer leaves will grow to deal with the light you are giving it now. Its not complicated.

Think about going to the beach for the first time after a winter indoors. You know you need sunblock, a hat or whatever. You would suffer a terrible sunburn if you didn't. By the end of the summer, you can go outside without a problem or protection. By then you have a nice tan which protects your skin. Plants are the same. Just do it gradually.

Jane