Stainless Steel Soil Thermometer by Smart Choice Review

I bought this to more precisely time the application of “Halts” crabgrass preventer this spring. Crabgrass seedlings begin to grow when there are several days in a row of upper layer soil temperatures of 55 degrees F or higher. The crabgrass preventer works for about 4 months. If you put it on too soon, you extend the period of crabgrass emergence in August. If you put it on too late, you start the season with emerging crabgrass. You can put on 2 applications per year, but Halts interferes with the planting of new grass seed which most people do in the fall to overseed and repair damaged areas.

The thermometer is well made. Constructed of stainless steel it should not corrode when exposed to moist soil. I tested its accuracy comparing it to several other thermometers and it was accurate. It equilibrates/stabilizes after just a couple of minutes when moved to a new location.

Accuracy

Determining the Probe Sensing Area

I did the above experiment to determine what part of the probe was the active sensing portion of the thermometer. I found that it wasn’t the tip of the probe or the entire probe, but instead was the distal/last 2 inches of the probe. Therefore, if you want a reading at a specific depth you should insert the probe at a depth 1 inch greater than that you want to measure so that the last 2 inches of the probe are centered at your target depth (1 inch above and 1 inch below target depth). If you were to insert it only 1 inch deep then 1 inch of the sensing portion of the probe would be reading air temperature.

Other Options

After getting the thermometer I began to wonder if people provide this information via something like a weather report and guess what? They do. Here is a report from Rutgers on New Jersey Soil Temperatures:

https://www.njweather.org/maps/nj-statewide-soil-temperatures-10cm

You can view the report at 5cm, 10cm, 20cm and 50cm depths at various location around New Jersey. The same type of report is available for pretty much anywhere. Below is a sample report at 5cm (2 inches) depth on 3/16/2019.

Still, it doesn’t hurt to have your own thermometer because there are local variations due to differences in shading, wind exposure, etc. If you have your own outside thermometer or rain gauge you know what I mean.

Below is a video review of this thermometer I uploaded to my YouTube channel “Arnold Solof”.

Conclusions

The thermometer works well and helps you time gardening tasks to allow you to get the most bang for your buck from the products you purchase and optimizing the results for your gardening efforts.

It is available on Amazon but its price fluctuates widely between 15 and 25 dollars. I paid about $20 for mine.