How Important Is Soil Temperature?
Plant care involves more that fertilizing and watering them. Right from the start, putting plants in unhealthy soil will affect their growth, and many factors affect soil health. So, how important is soil temperature?
Soil temperature is extremely important because it affects nutrient absorption and water evaporation rates. Cold soil can quickly become waterlogged, and extremely hot soil can slow the growth rate and dehydrate plants. Plants typically thrive in 65-75-degree soil, but it varies by climate and plant type.
It’s important to keep a soil thermometer on hand, as the soil doesn’t always match the ambient air temperature. Follow along as we explore how important soil temperature is and highlight the factors that affect it.
Why Is Soil Temperature Important?
Soil temperature is one of the most important parts of your plants’ success for many reasons, including:
1. Root Growth
Root health should be a priority. Roots become dormant in extremely cold soil and become stressed in extreme heat. However, there’s a lot more nuance to it than that, and that’s why understanding soil temperature is so important. How hot or cold the soil is will largely affect the root's growth rate and structural development. Roots grow best in the 65 to 75 degree Fahrenheit range.
This moderate temperature range helps roots easily uptake water and key nutrients, like nitrogen and potassium. Once the soil temperature exceeds 80 degrees, the roots may shrink, and the growth may slow. Similarly, root development slows when the soil temperature falls below 50 degrees Fahrenheit. Soil temperatures change with the seasons, and it’s part of the life cycle of plants.
2. Seed Germination Success
Seed germination poses problems for many people who wonder what went wrong. If this has given you a lot of trouble, there’s a good chance it was because of the soil temperature. Temperature affects how quickly seeds germinate, but it’s more complicated than that. For example, if you plant seeds in cold soil, they may eventually rot and suffer from fungal diseases.
That’s because water lingers in cold soil much longer than it does when it's warm. Mold and fungi thrive in cool, damp soil, and they can easily target your seeds. Conversely, seeds can absorb water and germinate much faster in warm soil, as they’re less vulnerable to rot and disease. You will notice a much higher success rate when you plant seeds in soil that is between 68 to 86 degrees Fahrenheit. It’s important to measure soil temperature and check the weather forecast before planting seeds.
3. Nutrients And Microbes
Healthy soil contains many microbial organisms, also known as microbes, and they’re the unsung heroes in any garden. These microbes recycle, unlock, and produce key soil nutrients that your plants need to grow and thrive. Microbes feed on decomposing plant matter and other organic waste, then recycle it. Soil temperature not only affects microbial activity, but it also impacts nutrient availability.
Microbes can process organic matter and release nutrients more easily when the soil is between 60 and 85 degrees. The microbes will slow down once the temperature drops below 60 degrees, which can affect your plants. Conversely, microbes can easily die when in 100-140-degree soil. In that case, you may want to introduce some shade to help the soil cool down in that part of your garden. Otherwise, your plants will suffer from nutrient deficiencies, and the roots will struggle to absorb water.
4. Evaporation Rate
How quickly water evaporates from soil is just as important as how quickly roots absorb water. When water evaporates quickly, the roots cannot absorb nearly as much moisture. If it takes too long to evaporate, the plants won’t receive enough oxygen. A slow evaporation rate can also waterlog and smother the roots, leaving them vulnerable to root rot.
Waterlogged soil is just as bad as overly dry soil, so you must find a happy medium. The evaporation rate will reach an unhealthy level when the soil temperature exceeds 90 degrees Fahrenheit. You can slow the evaporation rate by adding peat moss, compost, and mulch during the summer. If the soil becomes waterlogged, you must aerate it and stop watering the affected plants until they recover.Â
What Affects Soil Temperature?
Everything from the sunlight and ambient air temperature to your soil’s color can affect its temperature. Most people realize that soil temperature correlates with the day’s weather. That said, how and why these factors affect soil temperature can get complicated.
Sunlight
Nothing affects soil temperature more than sunlight. Naturally, your soil will get much hotter, much faster if it sits in direct sunlight on a hot day. The angle of sunlight is a major factor, as soil in partial shade won’t heat up as quickly. Keep in mind that dark soil gets hotter much faster because dark surfaces absorb more heat. Soil doesn’t heat up nearly as quickly when it sits in the shade. Pay attention to the sun’s angle and intensity at different times of the day when planning your garden.
Surrounding Vegetation And Cover
Barren soil heats up much faster than covered soil, which can affect everything from root development to evaporation rates. Grass, weeds, flowers, crops, and other plants shield the soil from sunlight and heat. Groundcover plants also protect soil from extreme temperatures and reduce evaporation rates. This is true even in direct sunlight, as its rays can’t easily penetrate the soil’s surface. Adding plants to your garden can help reduce the soil temperature when your yard sits in direct sunlight.
Ambient Air Temperature
Sunlight may penetrate and heat the soil, but ambient air temperature also plays a big role. Ambient air temperature is a big part of what you feel when spending time outside. It won’t deeply penetrate the soil, but it does affect topsoil temperature. Throughout spring, your soil is typically 10 degrees cooler than the ambient air temperature. Conversely, soil temperature often exceeds air temperature during the summer, especially between July and August. Check the soil temperature on particularly hot summer days and change your care routine accordingly.Â
Summing It Up
Soil temperature is just as important as soil acidity and your watering habits. That’s because soil temperature affects root growth, seed germination rates, nutrient availability, and the water evaporation rate. Ideally, you should take your soil’s temperature on particularly hot or cold days and adjust how heavily you water your plants.
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Nick Durante is a professional writer with a primary focus on home improvement. When he is not writing about home improvement or taking on projects around the house, he likes to read and create art. He is always looking towards the newest trends in home improvement.
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