How Soil Temperature Affects Water Use In Summer

At A Glance

Rising soil temperatures increase evaporation, affect root activity and change how efficiently plants use water during summer. Managing heat buildup through mulching, shading and condition-based watering can improve water efficiency and plant health. Automated irrigation systems can support you further by monitoring conditions and managing different watering requirements for a variety of crops, delivering water at appropriate times throughout the season. 

Want to try it yourself? Buy products from the Harvst WaterMate range or build your own irrigation system that suits your growing space.

The Link Between Soil Temperature, Plant Growth and Water Use

If you’ve found yourself watering more frequently this summer, you’re not the only one. Across the UK and parts of the USA, recent heatwaves have brought prolonged periods of high temperatures and dry soil, putting increased pressure on vegetable gardens, allotments, greenhouses and polytunnels. 

Extreme heat events are becoming more common, creating new challenges for gardeners trying to maintain healthy crops through the warmest months of the year.

You probably pay close attention to factors that increase heat, but you might be overlooking conditions below ground. Soil temperature can rise significantly during hot weather, affecting moisture levels in the root zone. 

As soil dries out, water evaporates more quickly and plants may struggle to access the nutrients they need. The relationship between soil moisture and temperature, therefore, plays an important role in maintaining healthy growth and supporting crop performance.

So, does soil temperature affect plant growth in summer?

The answer is yes, as intense sunshine frequently alters soil moisture and temperature. This is most noticeable on raised beds, as well as in containers and spaces with lighter soils. That’s why it’s helpful to understand how soil moisture and temperature interact, so you can make better watering decisions and maintain healthier plants throughout the summer growing season.

How To Manage Soil Temperature To Improve Water Efficiency

Understanding how soil temperature influences water use is only part of the picture. You also need to know how to respond when the temperature starts climbing. 

A few well-thought-out measures can help you reduce moisture loss and create more stable growing circumstances. Let’s take a look:

1. Mulching To Reduce Heat Build-Up

To reduce increased soil temperature effects on plants, one of the simplest things to do is to mulch. Applying a layer of organic mulch helps shield the soil surface from direct sunlight. Materials such as compost, straw, leaf mould and well-rotted organic matter create a barrier between the soil and the air, helping the growing plants stay cooler for longer. 

Mulch also improves soil quality over time as it breaks down. This makes it a practical long-term approach to improving growing conditions while reducing the impact of warm soil water loss during summer.

2. Shading Soil During Heatwaves

Sheltered gardens, such as greenhouses and polytunnels, can trap heat throughout the day, causing soil temperatures to rise significantly above outdoor conditions. This creates conditions that place extra strain on sensitive crops. 

Temporary shade netting can help moderate temperatures around growing areas by reducing the intensity of direct sunlight without significantly limiting the light needed for photosynthesis. This approach is useful for young seedlings or crops such as lettuce and spinach, which are often more vulnerable to sudden temperature increases. 

Positioning shade over the soil surface can also help retain moisture for longer periods, reducing the frequency of watering during extreme heat.

3. Watering Based on Condition, Not Routine 

Your current watering habits are likely based on convenience. Watering every evening or every other morning can feel like a sensible routine, but weather conditions rarely follow a predictable pattern. 

A cool, cloudy week places very different demands on plants than periods of intense sunshine. Continuing with the same schedule regardless of conditions can lead to unnecessary watering in some situations and insufficient watering in others. 

Instead, take a few moments to assess the growing environment before you reach for the hose. Check the soil texture, recent rainfall, wind exposure and crop maturity, as these all provide useful clues about current watering requirements.

How Can Using Technology Support Smarter Water Management?

Let’s say you have the right knowledge to water your plants effectively, but you don’t have enough flexibility or consistency to put this into practice. 

This is where technology can support your growing process. When it comes to managing soil moisture and temperature, it can help in 3 key ways.

By Monitoring Soil Moisture Levels 

You don’t always have to conduct manual checks to monitor your soil moisture and temperature. Modern irrigation systems use sensor inputs and automated controls to respond to changing growing conditions throughout the season.

Systems such as Harvst WaterMate Smart Irrigation Controller use programmable watering schedules with sensor compatibility to help you adjust watering according to conditions. 

For example, when temperatures rise during a heatwave, you can adjust watering schedules to support plant health. On the flipside, when the weather is colder or overcast, you can reduce watering to avoid unnecessary water use.

This method gives you greater visibility into how summer soil conditions are changing around your crops while reducing the guesswork of summer watering. In greenhouses and polytunnels, where temperatures can fluctuate quickly, responsive irrigation management can help you maintain steadier growing conditions.

By Responding to Changing Summer Conditions 

Summer doesn’t affect every crop in the same way and that’s where technology can help. Fast-growing crops such as cucumber and tomatoes can have very different water requirements from root vegetables or leafy greens, particularly as plants move through different stages of growth. Similarly, a newly planted crop may require regular watering to establish strong roots, while mature plants often benefit from deeper, less frequent irrigation.

This creates a challenge if you’re managing mixed planting, as applying the same amount of water across an entire greenhouse or an allotment can lead to uneven results.

Harvst’s WaterMate system supports multiple watering zones, allowing different areas of a growing space to be managed independently. This makes it easier to accommodate crops with varying requirements and helps you tailor irrigation to the needs of your individual growing areas. 

To see a real-life example of how multi-zone irrigation can be implemented within a productive growing space, watch this YouTube video 

HUGE Polytunnel Upgrade | HARVST WaterMate Pro Automated Irrigation System

By Maintaining Consistent Moisture With Automated Irrigation

Summer watering isn’t only about supplying water. Your timing also plays an important role in how effectively your plants are watered. Watering during the hottest part of the day can increase evaporation, while inconsistent watering intervals can create unnecessary fluctuations around the root zone.

Automated irrigation systems deliver watering schedules at specific times without requiring manual intervention. Early-morning watering, for example, gives plants access to moisture before temperatures begin to climb, while scheduled irrigation can help you maintain suitable conditions when you’re away from your garden.

For smaller growing spaces, the WaterMate Mini provides a complete irrigation system designed for greenhouses, grow houses, cold frames and vegetable plots. It can operate from a water butt or main supply and support automated watering through programmable controls. In larger spaces, the WaterMate Pro offers greater capacity and flexibility. 

If you want to see a real installation, watch this video that shows how automated irrigation can be integrated into productive growing environments and demonstrates how scheduled watering fits into everyday garden management.

Setting up a Harvst Watermate Pro | Solar Irrigation | A Garden That Can Look After Itself 

Explore Smarter Water Management with Harvst 

As temperatures rise, it’s all the more important to protect the soil surface, improve soil structure, adapt watering practices and monitor summer soil conditions. These actions all contribute towards healthier crops and more efficient water use. Each element supports the next, creating a growing environment that’s better equipped to cope with summer heat.

If you’re looking to develop a more reliable watering system, Harvst offers solutions and growing tools for all kinds of growing spaces. Whether you’re looking for a wireless humidity sensor for your compact greenhouse or want to build a solar-powered irrigation system for a larger off-grid garden, the Harvst range offers several options to manage your growing space more efficiently.

Explore the WaterMate range or build a system that matches your setup.