Soil Temperature & Garden Pests: What Lies Beneath

July 18, 2025

When thinking about soil temperature in the garden, we often focus on seed germination and plant health, without digging deeper into the variety of factors that play significant roles in soil health, and in turn, plant growth. Beneath the surface, a whole other world is at work, including the emergence, activity, reproduction, and consequences of garden pests.

Understanding how soil temperature influences these unwanted guests can help you get ahead of infestations and protect your plants before damage sets in.

Why soil temperature matters for pest activity:

Controlling pests prevents your garden from becoming overrun with plant fatalities and poor crop growth. For gardeners, recognising common garden pests and understanding the damage they can cause to your garden is crucial for your outdoor space to thrive. Here are a few examples of common garden pests:

Aphids: Small, soft-bodied insects that tend to gather on plant stems and leaves. These pests suck the sap from these plants, causing curling or yellowing of the leaves. They also secrete honeydew, which can attract more pests such as ants and promote the emergence of fungal diseases.
Slugs and Snails: Slimy creatures that feed on the plants' leaves, leaving behind scattered holes and leaf damage. They can cause severe harm to young seedlings and delicate leaves. These pests can more often than not be spotted during the evening when conditions are cool and damp.
Beetles: These pests also feed on the foliage of various plants, resulting in chewed-up leaves and holes scattered around the leaf surface. Beetles are also known to target fruits, leaving them contaminated and inedible.
Wireworms: As larvae of click beetles, they thrive in cooler soils, most active in soils between 8 and 10 °C. They feed on plant roots, seeds, and bulbs. Preventing plant emergence and weakening roots. Their main victims include crops such as potatoes, carrots, and maize.

Many common garden pests live most or sometimes all of their life cycle within the soil. The temperature of the soil plays a crucial role in determining how and when these pests emerge, begin feeding, and cause plant chaos!

Unlike air temperature, which can fluctuate regularly, soil temperatures change more gradually, so conditions can remain stagnant for longer periods. therefore, if the environment is optimal for pest emergence, monitoring soil temperature can become even more vital for the success of your outdoor space.

Although some species have their specific preferred temperature range, Temperatures between 10 and 24°C are generally optimal for supporting pest growth and development. This is when regular soil checks and management are most vital. This range of temperature supports various biological processes crucial for these creatures' life cycle, including plant and crop growth, typical availability of soil moisture, and increased availability of soil nutrients. Understanding the relationship between soil temperature and pest activity is crucial for effective pest management.

Monitoring soil temperatures can help predict pest outbreaks and implement effective interventions. It acts as a valuable tool for pest and disease control. Here are some ways monitoring soil temperature helps growers:

Early detection of pests and diseases: Soil temperature monitoring can help growers identify if there have been any changes to soil moisture as well as temperature, as many pests thrive in warm and moist conditions. Monitoring your soil using tools like specialised thermometers provides growers with increased knowledge of what areas of their soil are at higher risk of developing a pest outbreak.

Inform gardeners when it is best to begin laying barriers or traps before pests emerge.
Rotate crops or avoid planting in vulnerable areas of your garden during high-risk periods, such as spring and summer.
Encourage gardeners to monitor soil moisture once the temperature is within the area of high risk, to stay ahead of large outbreaks of pests and diseases.

Track soil temperatures with confidence:

Monitoring soil temperature accurately is key to understanding your garden’s health, and a dedicated tool like a Soil Thermometer makes it simple. Our soil thermometers deliver precise, real-time readings from beneath the surface, helping you stay in tune with your outdoor space at a glance. For an even more accurate view, our Sun and Shade Bundle allows you to track multiple soil conditions simultaneously, giving you a fuller, more reliable picture of how your soil is performing across different areas of your garden.

CM3011 Soil Thermometer

Sun and Shade Soil Thermometer Bundle

FAQs:

What pests are influenced by soil temperature changes?
Many garden pests, such as vine weevils, wireworms, root-knot nematodes, and even slugs, time their activity based on soil temperature. Knowing when the soil warms up helps predict when these pests will become active.

How can I use soil temperature to prevent pest infestations?
By tracking soil temperature, you can anticipate when pests are likely to emerge and take preventative actions, like setting traps, or delaying planting before infestation begins.

How often should I check my soil during pest season?
During early spring and autumn are key times for the emergence of pests, therefore, it's a good idea to check daily or every few days, especially after warm spells or rainfall.

Can soil temperature affect the effectiveness of pest treatments?
Yes. Many biological treatments, like nematodes are only effective within specific soil temperature ranges. Applying them too early or too late can reduce their impact.

Where in my garden should I measure soil temperature for pest monitoring?
Check areas where you've had pest issues in the past, as well as where you plan to grow vulnerable plants. It's helpful to measure in both sun-exposed and shaded beds for the full picture.