Expected weather for this month:

Dry, settled start to the month with above average temperatures throughout

With Easter behind us and the temperatures heading steadily upwards to produce regular grass growth, it's all systems go. It is surprising how quickly the ground can dry up in May. Heavy clay and clay loam soils will begin to crack if left to dry out, and this is the last thing you want to happen to a natural turf tennis court. It will be imperative to get some water on the courts to prevent the soils drying and the grass plant suffering from heat stress. The key is to ensure the soil profile is watered enough to cope with the evapotranspiration rates (amount of water lost), which on a warm day can be as much as 6mm. 

It may also be a sensible option to raise the height of cut to help the grass plant tolerate any dry periods; just raising the height by 1-2mm will help.




Key Tasks for May

Rolling will be a priority; it is important to build up the rolling frequencies and gradually increase the weight to achieve maximum consolidation. However, it is important to note that we do not want to over roll or adversely compact the soil to the detriment of root growth, surface water drainage and active microbial populations.

Firstly, roll across the court followed by rolling down the length of play. Timing of this operation is vitally important. Trying to roll when soil conditions are wet or too dry will not achieve the desired effect. Ideal rolling conditions would suggest the soil be in a state of plasticity or "plasticine". 

Other regular tasks include:

  • Initial marking out of the grass courts, using the 3,4,5 method to ensure the lines are square and accurate. Ensure you use approved line marking paint for the line marking machine. 
  • Feed the sward with a spring/summer fertiliser product to maintain colour and vigour.

Mowing will be one of your main tasks during May, ideally at least 2-3 times a week, or even daily if you have the time and resources. However, this frequency will be dependent on a number of factors - grass growth, sward type, level or standard of facility, resources (staff and machinery).

Cutting height should be coming down towards 8-9mm (tournament height). Inspect the sward before mowing to remove any debris. Stones or sticks can damage bottom blades and cutting cylinders. Poorly adjusted mowers will result in poor presentation and damage to the grass plant, making the plant more prone to disease.

Fertiliser treatments and turf tonics can be continued in accordance with your annual programme. If you haven't got a fertiliser programme, have your soil tested; try an independent soil analysis company for an impartial set of results. Apply a spring fertiliser when conditions allow. Fertilisers can be applied in liquid or granular forms.

In May, you would be using a 13:5:10 fertiliser or similar or, towards the end of the month, apply a slow release fertiliser to see you through June and July. However, the choice of material and how well it works can be dependent on factors such as soil type, weather etc., with moisture and soil temperature being the catalyst for growth.


Whilst conditions remain unfavourable to granular applications, it is liquid foliar applications which are more likely to elicit a response form the plant, particularly when warmer spells of weather are forecast. Adding a small quantity (50 ml per 100 l tank volume) of a high quality liquid humate, such as Maxwell HumiMax, will further chelate the fertiliser, enabling it to pass into the plant leaf more readily for increased absorption and uptake efficiency.

Potassium is a plant nutrient traditionally favoured for autumn winter applications; however, potassium is absolutely critical to the efficient operation of plant stomata, the pores on a leaf’s surface which open and close in response to water demand. For this reason, a steady adequate supply of potassium during the spring and summer helps grass plants to better regulate water usage, increasing resistance to drought pressure.

Research is also increasingly understanding the importance of silicon applications as a preventative nutrient, which will strengthen plants resilience to a range of environmental and pest stresses.

Seaweed is another vital tool in the armoury when it comes to improving uptake of fertilisers and helping plants to resist stress, which should be regularly applied to all turf areas.

Wetting Agents

Utilisation of a penetrant and polymer wetting agent programme, which will drive water away from surfaces and into rootzones, where it can subsequently be stored more efficiently to be utilised by the plant, is a sound strategy for the majority of sports turf locations. Research the market and invest in high quality solutions. Prevention of dry patch with applications prior to symptoms is the most effective strategy.



Traditionally, the end of May presents a good time to spray for weeds in turf areas, applying herbicides immediately prior to, or during, periods of strong active growth. Again, adding a small amount of a liquid humate (50 ml per 100 l tank volume) will significantly aid herbicide uptake and efficacy.

Leather jackets and chafers are fairly prevalent at the moment. Merit can still be applied if people have it in stock, but it can be tricky to get a good kill when the grubs are at this stage of development.

As soils warm up, there may be some symptoms of plant parasitic nematode activity. There are two categories of nematode which will infect grass plants; Ectoparasitic which migrate along the outside of roots and feed accordingly on root cells and Endoparasitic nematodes which enter the root tissue and feed on the plants in these areas.

Be vigilant for the following symptoms:

• Yellowing and thinning of the turf

• Reduced turf vigour

• Premature wilt

• Turfgrass that is slow to recover from stress

• Turfgrass that does not respond to fertilisation

There are no legal chemical treatments; with entomopathogenic nematodes providing the only authorised cure. This situation is not going to change, but nematodes can be utilised successfully when applied correctly as part of a multi-faceted integrated approach. In the face of upcoming and projected further restrictions in other similar areas of the industry, there are a number of lessons to be learned from the withdrawal of insecticides within the sports turf industry. Now is a good time to reflect and prepare by seeking out avenues to embark on facing the upcoming challenges from the position of enhanced knowledge, understanding and proactive preparation.

Microdochium patch may also pop up as temperatures increase, particularly if the warmth occurs in conjunction with humidity and moisture on the leaf for prolonged periods. Systemic fungicides can be considered but only as a last option. IF grass is growing well and then the disease may well just bubble under the surface and the grass will outgrow it.

Please note: More information on these and many others can be found here: https://www.pitchcare.com/useful/diseases.php

Continue to keep on top of machinery maintenance:

  • Inspect and clean after use
  • Remember to check air filters
  • Inspect and reset mowing blades on cylinder mowers to ensure they remain sharp

Pitchcare provide a range of courses suitable for tennis clubs. In most cases, the courses can be held on site using the club's own equipment and machinery.

Some of the courses available are:

  • Chainsaws - CS30 and CS31
  • H&S Refresher Training on Combined Turf Care Equipment; Tractors and Trailers; All Mowers (Ride-on and Pedestrian)
  • Machinery Courses on ATVs; Tractors: Brushcutters/Strimmers; Mowers (ride-on and Pedestrian)
  • Pesticide Application (PA courses)
  • Stem Injection of Invasive Species (Japanese Knotweed etc.)
  • Basic Trees Survey and Inspection

More details about all the courses can be found on our new Grounds Training website, or you can email Chris Johnson for information.

Drainage: Inspect drainage outfalls, channels and ditches. Ensure that they are working. Renew or repair any damaged or problematic drainage systems.

Tennis structures: Inspect stored posts, nets, seating and notice/score boards. Replace with new equipment if required. Repair any damaged fencing.

Litter: Inspect and remove debris from playing surface - litter or any wind blown tree debris, twigs and leaves.