Beating heat stress this summer

These essential summer guidelines help stay ahead of heat stress, disease pressure and wear, ensuring pitches remain resilient when conditions are at their toughest.

As July heat, unpredictable rainfall and relentless fixture demands put natural turf under maximum pressure, even small weaknesses in the rootzone, irrigation strategy or mowing regime can quickly escalate into major surface problems.

The next few months brings a mix of prolonged dry spells, sudden thunderstorms and high humidity - conditions that expose weaknesses in the turf system and test even the best prepared surfaces. Heat stress, increased evapotranspiration and relentless wear combine to push surfaces to their limits.

Start below the surface

Summer is when earlier decisions either pay off or catch up with you. If there’s compaction or poor drainage lurking in the rootzone, hot weather will expose it. Restricted pore space limits both water infiltration and gaseous exchange, leaving roots unable to access moisture and oxygen when demand is highest. The result is shallow rooting, reduced stress tolerance, and surfaces that deteriorate rapidly under pressure.

Where possible, lighter spiking operations can help maintain air exchange without causing excessive surface disruption. Solid tine aeration at 75–100mm depths, carried out at appropriate intervals, keeps the upper rootzone functioning without the recovery time associated with deeper hollow coring.

For surfaces with persistent drainage issues, wetting agents become increasingly valuable. Soil hydrophobicity - where organic coatings on sand particles cause water to bead and run off rather than infiltrate - is exacerbated by dry conditions. A well timed wetting agent programme ensures moisture moves evenly through the profile rather than creating localised dry spots.

Moisture meters are especially useful in July, helping identify areas drying faster than others and preventing chronic dry patch formation.

A Dollar spot outbreak on a green. 

Irrigation: strategy matters

With water restrictions increasingly common across the UK, irrigation must be efficient and deliberate.

• Water early morning to reduce leaf wetness duration and disease pressure.
• Use pulse irrigation on hydrophobic areas - short cycles improve infiltration.
• Aim for deep and infrequent watering where possible to encourage deeper rooting.
• After thunderstorms, reassess moisture levels; saturated surfaces followed by heat can create ideal disease conditions.

Irrigation and wetting agents work best together - one manages volume, the other manages distribution.

Rethink your mowing heights

There’s always pressure to deliver tight, fast surfaces, but dropping too low during extreme heat weakens the plant. The relationship between cutting height and root depth is well established: reducing leaf area limits the plant’s photosynthetic capacity, which in turn restricts carbohydrate production and root development. During periods of heat stress, this creates a downward spiral that’s difficult to reverse mid season.

Even a couple of millimetres extra provides greater leaf area for photosynthesis and offers natural shading to the crown, helping moderate soil temperatures at the surface. The visual difference is minimal, but the physiological benefit can be significant.

Mowing frequency also warrants consideration. Removing no more than one third of the leaf blade at any single cut reduces stress on the plant.

During rapid growth periods, this may mean more frequent mowing rather than taking off excessive material in a single pass.

Sharp, well maintained blades are essential as torn leaf tips increase moisture loss and create entry points for disease.

Adjust your nutrition programme

Summer isn’t the time for aggressive nitrogen applications. High nitrogen availability promotes lush, succulent growth that’s more susceptible to heat stress, disease, and wear damage. Backing off and focusing on potassium helps harden cell walls, improve drought tolerance, and build overall stress resistance.

A ratio shift towards higher potassium relative to nitrogen - often moving from spring ratios of 3:1:2 (N:P:K) towards summer ratios closer to 2:1:3 or even 1:1:2 - supports this transition. Spoon feeding light, regular applications can maintain colour without forcing growth.

Foliar micronutrients such as iron, manganese, and magnesium are well suited to summer conditions, helping maintain colour and photosynthetic efficiency without pushing excessive leaf growth.

Biostimulants, including seaweed extracts, amino acids, and humic substances, have gained traction in recent years. While responses can be variable, there is growing evidence that these products support root development, improve stress tolerance, and enhance nutrient uptake efficiency. They’re not a replacement for sound agronomic practice, but they can be a valuable addition to a summer programme.

Quick checks for rootzone health

• Probe depth: Aim for consistent rooting >80mm
• Moisture meter: Identify hydrophobic zones early
• Surface hardness: Rising readings often signal compaction
• Smell test: Anaerobic odours = poor air exchange

Manage wear intelligently

Fixture congestion leaves surfaces with limited recovery time. While the schedule can’t be controlled, the response to it can. Moving goalmouths between fixtures, rotating penalty spot and centre circle locations where regulations permit, and varying training areas all help spread wear more evenly across the surface.

Communication with coaching staff is essential. Understanding training intensity, session duration and specific drill locations allow grounds teams to anticipate wear patterns and plan recovery windows accordingly. Many clubs now use GPS tracked training data, which can be extremely helpful for predicting high stress zones.

Growth covers and germination sheets can accelerate recovery in high wear areas by creating a favourable microclimate for seed establishment and plant growth. Used strategically during gaps in the fixture schedule, they can make a meaningful difference. However, overuse can create soft, humid conditions that favour disease, so judgement is required.

Stay vigilant on disease

Warm, humid conditions are ideal for fungal pathogens. Dollar spot (Clarireedia spp.), brown patch (Rhizoctonia solani), and anthracnose (Colletotrichum graminicola) all become more prevalent during summer months, particularly when night temperatures remain above 15°C and humidity is high. After summer storms, even Microdochium can appear in sheltered, slow drying areas.

Maintaining plant health through balanced nutrition and appropriate irrigation provides the first line of defence. Stressed turf is susceptible turf. Avoiding excessive nitrogen, ensuring adequate potassium, and preventing prolonged leaf wetness all contribute to an environment less favourable for pathogen development.

Cultural controls play a significant role. Morning dew removal - switching, rolling, or mowing - reduces the duration of leaf wetness. Improving air circulation through selective pruning of surrounding vegetation, where practical, also helps surfaces dry more quickly.

Regular scouting remains invaluable. Walking the surface daily and looking closely catches problems early, when intervention is most effective.

When fungicide intervention is required, product selection, timing, and application technique all influence efficacy. Rotating between different FRAC groups helps avoid resistance development.

Get the basics right, stay vigilant, and don’t be afraid to make adjustments as conditions change. Summer rewards those who prepare - and punishes those who don’t!

Don’t overlook the team

Summer stretches staffing capacity. Heat, long days and fixture demands can lead to rushed decisions. Prioritising essential tasks during heatwaves, rotating staff to avoid fatigue and ensuring daily surface walks all help maintain standards when workloads peak.

Renovation is essential

Even with the best preparation, summer takes its toll. The most effective end of season renovation programmes are those planned well in advance. Getting materials ordered, contractors booked, and timelines confirmed now avoids unnecessary pressure when September arrives.

• Order seed and topdressing materials by mid August.
• Confirm contractor availability before pre season friendlies begin.
• High wear areas may require deeper aeration, heavier topdressing, or localised rootzone amendment.
• Areas that have performed well might need only light renovation.

Seed selection deserves careful thought. Cultivar performance data, such as that provided by BSPB Turfgrass Seed, allows evidence based selection rather than relying on habit or price alone. Disease resistance ratings, wear tolerance, and recovery speed all vary considerably between varieties.

Take a look at the May/June 2026 issue of Pitchcare, where ICL discuss why density should drive seed selection on elite pitches and how it impacts stability, recovery and playing quality. Click HERE