soil temperature vs air temperature; what is soil temperature; best soil thermometer

Ground Temp Vs Air Temp: Everything You Need To Know For Gardening

Knowing details and comparing ground temp vs air temp is mandatory for every gardening enthusiast. Do you know soil temperature vs air temperature is a constant battle of difference? That means ground temp and soil temp constantly are different from each other.

While this difference exists, the care regime of plants and trees needs to change following the change of specific temperatures. For example, sometimes, the soil temperature is higher while the air temperature is higher.

This article will discuss everything you have to know regarding ground temp vs air temp. In addition, we will talk about how you can measure them with or without a thermometer, and we will also show you specific care regimes that you have to undertake according to the soil temperature vs air temperature.

How Does Temperature Affect Plant Growth?

Let’s take a Christmas cactus, for example. If you keep the plant in a room where it is bright all day long and the temperature is pretty high, the plant’s flower will never bloom. So there is certain daylight and temperature required for Christmas cactus to bloom its flowers. 

You have to place the plant in a dark room at least 12 hours a day, and the optimum temperature should be 50°F to 55°F for the flower buds to form. 

Not only in the case of Christmas cactus, let’s talk about papaya plants. Papaya is a warm area fruit. For the plant to grow properly and bear fruits, the optimum temperature has to be between 70°F to 90°F. And for the root to remain healthy and develop strong, the soil temperature must be above 60°F. Anything lower would cause the papaya plants to have improper growth.

ground temp vs air temp; temp difference in shade; constant ground temperature

What is Soil Temperature?

To put it very simply, the temperature of the soil is called soil temp. In a more technical term, finding out the internal energy or the soil’s heat can be described as soil/ground temperature. If the definition is so easy, why would you need such descriptive discussion about it? That’s because there are a lot of factors included here.

Why Knowing Soil Temperature is Important?

Variation of soil temperature is directly related to a plant’s growth. So, if you don’t know about the soil temperature before planting a seed or a plant, it will face many issues if the temperature is not precise. 

In the case of seed germination, a few crops are considered cool crops. For example, spinach, lettuce, and radish are cool crops that require 550 to 650 F for germination.

Then there are warm-season crops that need a higher temperature for germination. The best examples would be lobelia, tomato, and petunia. These plants require 650 to 750 to germinate.

Let’s find out the minimum required and optimum soil temperature of a few commonly grown plants-


  Minimum Soil Temperature Required (°F)

Optimum Soil Temperature (°F)



65° to 95°



65° to 75°



85° to 95°



65° to 85°



75° to 85°

You can go a bit over the bare minimum requirement. But if it exceeds the maximum temperature or does not cross the minimum required temperature, the seeds of these plants will not germinate.

How to Measure Ground Temperature?

You can seek the help of a soil thermometer for determining the temperature of a specific spot within a 2-inch soil depth. Then, you can go even more profound. The temperature is designated as either 0C or 0F. 

A soil thermometer is pretty cheap. You can even use the thermometer for cooking purposes. It’s the same sort of thermometer. 

Are there any average soil temperatures?

You can never determine average ground temperatures. You can only choose the current ground temperatures. Even there is a temp difference in shade.

So, it’s possible to get accurate results on how hot the soil is, but you can’t determine the constant ground temperature.

According to, the average ground temperature of the earth is around 570F. But, the ideal ground temperature for most of the plants grown around the world is between 650 to 750F. 

What is Air Temperature?

Knowing how hot or cold the air is can be identified as air temperature. To be a bit technical, determining the kinetic energy of the gasses present in the air is known as air temperature.

Why Knowing Air Temperature is Important?

Higher temperature evaporates the soil moisture content and humidity from the air. When air exceeds its heat capacity, colder air from other sides fills the void and turns the scorching heat into radiant heat.

So, places with a lot of heat can also have a lot of wind. Also, you can determine the direction of weather by assessing the change of temperature in the air. For example, warm soil temperatures or soil water content may not indicate when it will rain, but the same thing in the air can.

The following table shows the optimum air temperature for daytime and nighttime to ensure maximum growth for plants.

Growth Time

Optimum Air Temperature (°F)

Day time growing

70°F to 80°F

Night time growing

60°F to 68°F

How to Measure Air Temperature?

There are a lot of methods with which you can measure the range of air temperatures of a particular place. The 4 main instruments that you can use to measure air temperature are –

  • Bulb Thermometer
  • Infrared Thermometer
  • Thermoelectric Thermometer
  • Spring thermometer

Using any of these, you can precisely determine the air temperature of a specific place.

How to Warm Soil for Early Planting?

In areas with colder weather, it will take a lot of time to wait for the soil to get warm enough to start planting. So, garden enthusiasts often use a method to ensure the artificial increase of soil temperature. However, this method is not suggested in areas where the basic soil temperature regime will not take much time to warm up.

But if you are all about early planting, you should follow these steps- 

First, select the area where you want to plant the seeds or the plant among so many soil types. Choosing the place is essential because no matter how warm you make the soil if it is not perfect for the plant, it will not grow.

Now, cover the soil with a sheet of plastic. Leave it for at least 6 weeks; the faster you apply this method, the earlier you can start planting. 

After 6 weeks, take the sheet off, clean the place, take the weed out. The soil is now ready for planting. Of all the ways to increase soil temperature, this is the most effective and least time-consuming method. Following this method will help you reach optimum soil temperatures for planting.

Another method of heating the soil is through thermal conductivity. You have to jump-start the soil using soil heating cables. With this method, you won’t require the waiting of 6 weeks.

Our Recommendation

We have discussed many things; now, we mentioned a few necessary tools for certain work. Of course, you could get them anywhere, but we recommend the best tools needed to ease your problem.

Soil Warmer Cable

soil temp vs air temp; best soil warming cable

For warming up the soil in no time, you can use this soil warming cable. This is an actual product, but if the wires are not fit for the job, you might end up on the earth, but it won’t warm up the soil. 

For warming the soil up correctly, you need the best cables you can buy. The line comes with an automatic activator that activates the cable electricity supply whenever the temperature starts to go below 74 degrees. In addition, it’s 24′ long, so you don’t have to worry about connecting the cable to a power supply. 

Soil Thermometer

best soil thermometer; soil temperature thermometer

To check the soil temperature, what you need is a soil thermometer. Yeah, you will need a temperature cable to warm the soil up, but to know how warm the ground needs to be, you have to determine the existing soil temperature first. 

So here’s the best soil thermometer for you from Smart Choice. Smart Choice is a well-known brand that has been producing thermometers. However, unlike most soil thermometers, this one can be used indoors and outdoors planting.

Indoor Outdoor Air Thermometer

ground temperature vs air temperature; best air temperature thermometers

Air thermometers are becoming digitized. There are still analog air temperature thermometers, but people are switching to digital thermometers because of the complication they impose. So, here’s the best outdoor air thermometer for you, Newentor Weather Station.

It’s a screen that looks like a digital wall clock. In clocks, the time and date are focused. As it’s not a clock but a thermometer, the temperature, humidity, wind speed, and overall weather forecast for the next 8 hours can be seen on the thermometer screen. It’s a handy device to keep at home.


1. Is ground temperature higher than air temperature?

It’s a straightforward variation. During the daytime, the air is hotter, and the soil is cooler. But at night, the soil is hotter, and the atmosphere is cooler. As soil density is more than air, the air heats up and cools off quickly. But soil absorbs the heat and radiates the heat starting from sundown.

2. How does soil temperature affect air temperature?

After sundown, when the soil starts to radiate the heat it absorbed through the day, the heat is radiated into the air. Thus, the air can also become hot at night.

3. What is the relationship between air temperature and soil temperature?

The relationship between soil and air temperature is straightforward yet complicated. The warmer air temperature evaporates the soil moisture and dries it up. But, on the other hand, after sundown, the heat radiating from the soil heats up the air for a certain amount of time. 

4. Is soil temperature more important than air temperature?

In the case of planting, yes. Soil temperature is slightly more important than the air temperature. But that does not mean air temperature is not taken into account. So, technically, soil temperature and air temperature are almost equally important.

Final Words

To perfect your gardening skills, you will need an understanding of the Ground Temp Vs Air Temp concept, and we have discussed everything about it above. 

Another skill you need to master is how to improve the soil structure. One way you can improve your soil’s status is by adding compost. 

I have written an article on preparing compost and using it in your garden. Here it is: How to Use Compost in The Garden for Highest Yields.

Picture of Robert Silver

Robert Silver

Robert Silver is a writer, speaker and certified master gardener who has been sharing his landscaping experiences through personal blogs. Taking it to the next level, Robert Silver has come up with this to shine a light on new planters and experts, discussing plants, landscape projects and much more. He has published numerous research articles on horticulture that have helped many people attain fruitful outcomes.