LTH Meter – House Plant Journal

LTH Meter

Light | Temperature | Humidity Meter

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Measuring and Interpreting Light

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Back Story

Very early in my houseplant journey, I realized the term ‘bright indirect light’ was a meaningless catch-all phrase that didn’t give you any concrete way of assessing the light your plant was getting.

People gave vague guidelines like high, medium, low light or attempted to categorize light by window direction, as if everyone had exactly the same sized windows and external obstructions.  These vague directions made it difficult to set your expectations on how well your plant will grow.

That’s why I started measuring indirect light.

Our eyes can easily see if the sun is shining directly on a plant but it’s the INDIRECT light (or ‘diffused’, ‘ambient’) that we have difficulty assessing.

When I started measuring light, I realized that there could be a 10x difference in the measurement only a few steps away from a window – and our eyes just cannot detect this difference – it doesn’t FEEL that different!

So I compiled a table of many popular “bright indirect light” houseplants and suggested light levels that would yield good growth:

One last problem: convincing houseplant owners that getting a light meter would be the most helpful tool they’ll ever use.

The light meters currently on the market were bulky and awkward to use or very expensive for just one function.

I wanted a meter I could easily carry in my pocket that looked great.

I wanted an accurate light meter that worked for both natural light and white LED grow lights.

I wanted device that could also measure temperature and humidity – other important factors in plant growth.

I knew I had to create it myself:

After two years of design, development and testing, the LTH Meter was born.


Features of the LTH Meter

1 – Convex Mirror
Correlate your visual surroundings with the light measurements

2 – Light Sensor
Measures light in FC (foot-candles) or lux

3 – Temperature/Humidity Sensors
Measures temperature in °C or °F and humidity in %

4 – Display
Shows measurements for light, temperature and humidity in real-time (refreshed every 0.5 seconds)

5 – Wrist Strap
Sturdy, custom woven wrist strap