It is a digital moisture sensor that tests a potted plant's soil once per second. As it becomes drier, it changes its blinking pattern to let you know when to water the plant. If you are like me, I forget to water my plants on a regular basis. I am busy and I tend to neglect my houseplants until they are desperately thirsty. Then for a few weeks I am remorseful and water them too much.
The Thirsty Light is designed to prevent underwatering by blinking its low power LED light when water is need. It is also designed to avoid overwatering - unless it is blinking, it probably doesn't need water.
It was not as useful in a flowerpot that needs to stay constantly moist. By the time the light blinks, the plant is already too dry. I tried it in a potted azalea that was always showing signs of wilting, since there were several plants in a small pot with a lightweight potting soil that didn't hold enough water. If I waited until the light came on, the azaleas were really wilted. The company's Web site does mention that it should not be used for plants needing constant moisture.
The sensor can be used two ways. You can leave it on and put it in a flowerpot. Just put the 4-inch sensor in the soil and aim the light in a direction that you will be able to see it when it starts blinking. It doesn't do any good to have it hidden by foliage. It is small and green - it's not very noticeable, unless it is blinking.
Move it around from pot to pot testing the soil in each one to see if the plant needs to be watered. It will measure the soil moisture in as little as one second and then you move to the next plant.
The probe is testing the electrical conductivity of the soil, which is influenced by the amount of salt in the soil. A soil that has a lot of dissolved fertilizer in it may read wet when the soil is actually dry; therefore, watch the plants for any wilting when you first start using the probe to see how accurate it is on your plants.
Potting soil dries out from the top and down. The sensor will read the moisture depending on how far it is pushed into the soil. If you want the sensor to be sensitive to drying out, don't stick it too far into the flowerpot. You can fine-tune the sensor for a plant's moisture needs depending on how far into the soil you place the probe.
The only maintenance required is an occasional wipe down of any mineral salt buildup as well as an eventual battery replacement. Before the batteries go dead, the light blinks in a new pattern to let you know they need to be replaced.
I would love for the company to make a version of the Thirsty Light to use outdoors in my lawn and flower beds. Another place that I would like to measure the moisture is in my compost pile, so a long probe version would be nice.
OK, let's move outdoors for a minute. I was at a garden writer's trade show a couple of years ago when I talked with a lady that I did not know. At the end of our time together she gave me a small gift box. Later when I opened it, I found a unique garden gift idea. It was several sets of round 1 1/2-inch mirrors glued back to back with 2 feet of braided fish line and another pair of mirrors on the other end.
I put them all on a small ornamental tree in my front yard and was surprised at how much attention they receive. They reflect beams of sunshine into my house to brighten up any room. They also run streaks of light across the yard and onto the house which keeps the cat across the street busy watching out the window. They have turned an unnoticed tree into a kinetic light sculpture.
They are a simple, inexpensive decoration that usually blends in and isn't obtrusive. But when the sun is out and there is a little breeze, the beams of sunshine bring excitement into the landscape. The small mirrors and string are available at craft stores and it only takes a few minutes to glue them together. The only needed maintenance is an occasional untangling as the wind sometimes blows them over other branches, inhibiting them from hanging down or move freely.
I would not have thought that such a simple gesture would bring so many people some happiness. I leave them up year-round. In the winter when the leaves are off the tree and the lights are up, they reflect them too. In the summer when the tree is fully leaved, the beams of light have to sneak out between the leaves. I haven't noticed if the birds are afraid of them, or if they even pay attention to the light.
Go and spread the light.
E-mail questions to Jeff Rugg, Kendall County unit educator, University of Illinois Extension at jrugg@uiuc.edu.
