Lawn Care Experts

May 2018 Lawn Diary

May Lawn Care Diary by Lawnsmith

This Month in a Nutshell

If you managed to get your moss raking done last month then this month should be easier on your back!

Summary 'to do' list for now through May:

  • Fertilising
  • Weed Control
  • Aeration
  • Top Dressing
  • Repairs and Seeding

A trying April!

A tough month for lawn care for quite a few of you with low temperatues.

Soil temperature is one of the main factors influencing growth and seed germination. Air temperature is important to us but for grass, soil temperature, from the surface to 4" down is the important bit and where seeds and roots lie. Temperature controls germination of seeds, uptake and response to fertiliser and therefore growth. Many of you will have done fewer cuts than normal in April which is typical of a slow cold start, but this also means the grass has less need for fertiliser therefore taking longer to green up and seed has poor germination rates.

So, how to proceed. If grass growth, greening or recovery after raking or scarifying is your main concern then it will occur but more slowly and later than normal. All will come good as temperatures rise. The main issue will be for none germinated seed whether from over seeding or starting a new lawn. As seed is pretty resilient stuff, once conditions improve it will get going as long as the birds haven't got to it first.

The next issue is whether or not to continue watering if you've seeded? Well, the bad news is that watering adds to the cooling effect so if you've been diligent with your watering you've unintentionally contributed to the problem! So, perhaps less watering until it warms but don't back off too much as once the seed germinates it mustn't dry out otherwise it dies.

The Weather

May Forecast courtesy of the Met Office:

UK Outlook for Sunday 29 Apr 2018 to Tuesday 8 May 2018:
Northern and western parts of the UK should be mainly dry on Sunday and Monday, except for the odd shower. In the south and east it is likely to be changeable with showers or longer spells of rain and stronger winds. Temperatures will be close to average but along North Sea coasts it will feel colder with easterly winds. Mixed conditions will then continue through the first week of May with brisk winds and spells of rain at times, perhaps with some snow over the Scottish mountains. Some drier and sunnier spells too. Temperatures will remain close to average throughout, but at times it will feel colder with a greater risk of frost overnight, especially in the north.

UK Outlook for Wednesday 9 May 2018 to Wednesday 23 May 2018:
Mixed weather conditions are mostly likely to continue into early May, with showers or longer spells of rain, interspersed with drier and brighter interludes. A more settled spell may develop for a time in early May, especially in the north. Thereafter, there are some signs that from mid-month it may become drier and settled more widely across the UK, although confidence in this aspect of the forecast is low. Temperatures are likely to be variable during this period as is often the case at this time of the year, averaging out close to normal. However, if a drier and more settled spell develops, then temperatures may become warmer than average.

As always it's advisable to consider the weather and ground conditions before undertaking any lawn care jobs and treatments. Heat, drought, frost and excessive rainfall all require some adjustment to your lawn care regime though without a crystal ball we can all get caught out on occassions.

Mowing the Lawn

A late start to mowing for most but do keep on top of it as rain and wet ground could make mowing difficult. Therefore mow at every opportunity - if you miss a week you can guarantee the weather will stop you mowing until the grass is up to the window cill! Depending on conditions adjust your mowing:

  • If the ground is wet 'squeegee' the lawn first and then mow in the afternoon to allow the grass drying time
  • Keep the cut on the high side if growth is slow due to soggy cold ground or dryness
  • Be careful with the turns if the ground is soft
  • Lower the cut when growth picks up

For the future, if mowing to preserve moisture then you need to mow as high as possible:

  • Grass is 85% water - removing grass therefore removes water
  • Long grass creates a barrier between drying sun and wind and moist soil
  • Long grass keeps the soil cooler
  • Long grass traps more dew and with low night time temperatures at present there are heavy dews about giving the lawn a daily drink
  • If the mower instructions allow mow with the box off. If you have set the mower to just take the top off then these fine clippings will disappear in 24 hours returning valuable moisture to the lawn. CAUTION: If weeds are seeding (flowering is not a problem) then best keep the box on.

You also need to mow with sharp blades to minimise loss of water through jagged cuts with blunt blades.


For the mowing season you need to do two things: keep it clean and keep it sharp. If the grass is damp it can easily build up inside the mower so always give the mower a good brush, scrape or hose down after every use. Secondly, if you do a lot of mowing, then be prepared to sharpen or swap blades mid-year to maintain a clean cut.

Fertilising the Lawn

If you haven't already fertilised the lawn, this month is still a good time to apply a spring feed if conditions are suitable. If you're doing any other lawn maintenance then put your lawn fertiliser in afterwards.

There are a variety of Lawnsmith® Fertilisers that can be applied at this time of year. Being granular and slow release they offer gentle growth, a high degree of grass safety and are perfect for getting the grass revitalised and in condition. The choice is simple and based around your soil and your enthusiasm for lawn care:

  • Getting a fertiliser into the lawn that contains potassium will help greatly with the moisture control functions of the plant. If you fancy adding some extra then spraying our soluble SOLUGREEN fertiliser through a knapsack or watering can gets it straight into the leaf where it does the most good.
  • Dry (not liquid) or Granular Fertiliser MUST be slow release
  • Only use granular products (pellets 1mm to 4mm in size) as these have reduced scorch potential. Powdered products have a much higher scorch risk.

Spreading Fertiliser Videos Spraying Videos View Fertiliser Range

Weed Control

The weeds are also a little behind schedule so don't rush to apply anything just yet. Chances are the end of May and all of June will be the best time to apply weed killer to the whole lawn either by knapsack sprayer or watering can and get a good result.

If you've been diligent with your weed control and have few weeds then keep at it with a combination of spot treating individual weeds with a Ready to Use Weed Killer or manually removing any obvious large weeds.

See Weed Identification for more detail and control methods.

Watch the Video See Weed Killers

Moss Control

Normally it's getting a bit late to start a full moss control programme, but the cold conditions may mean moss removal has had to be delayed. Be patient, you can rake anytime growth is good so late May or even June! The main problem with renovation in early summer is that it may turn hot and dry (chance would be a fine thing!) which in turn will mean problems with recovery and getting seed to germinate if the area cannot be watered. As a last resort it can always be postponed until autumn.

Caution - weeds are now flowering and seeding so any damage from raking/scarifying may result in a few extra weeds. So, be gently with the raking and make sure you over seed bare areas and have a supply of weed killer on hand just in case.

Please also note you may cause some transient grass burn to the lawn if applying a ferrous sulphate based moss killer in dry conditions. In dry conditions pop the sprinkler on the lawn for just 10 minutes before treatment to give everything a soaking. Perhaps treating at the end of the day would also be beneficial. Do NOT apply ferrous sulphate on new seedlings.

Finally, it is worth reflecting that getting too heavy handed with the lawn in spring might not be such a good idea. At Lawnsmith we have always promoted raking, moss control and light scarifying in the spring with more invasive scarifying and thatch removal for the autumn. Though this strategy helps avoid a spring weed invasion it is not much consolation if a hard winter left you with more moss than grass and once it's removed you're left with a lot of bare soil! If this is the case then keep at it, over seed, fertilise, perhaps adjust some lawn care practices and your grass will improve and moss invasion will be less.

See Lawn Scarifying & Raking for procedures.

Watch the Video Moss Killer Products

Watering the Lawn

Normally I only recommend watering if you have put new grass seed or turf down, or prior to applying ferrous sulphate if conditions are dry. I've always believed that a properly fed and cut lawn will ensure deep roots and good colour in all but the driest summers. So, if you are going to water please read Watering the Lawn, it'll help you get the most out of watering and prevent some unwanted side effects such as red thread.

Aeration & De-compaction

As discussed in Lawn Aeration Advice, aeration is highly beneficial if done properly. Using lawn aerators such as a rolling aerator or aerator sandals makes it relatively easy. At the least you should be looking to use a fork on the most trafficked areas around clothes lines, path-to-lawn entry points, kid's goal mouth and postman's shortcut. Add grass seed to any worn areas after aeration then fertilise.

The benefits may not always be obvious but a well aerated lawn will stay greener longer in dry weather, utilise showers more readily and allow excess water to move through the soil more easily. Spring through summer is the ideal time to be spiking with aerating sandals, roller or garden fork. Even when the surface is getting firm light aeration or pricking, perhaps only 1cm deep will open the surface to better accept the briefest shower.

Please note that it is now too late to be slitting or using a hollow tine aerator unless you can irrigate. These increase drying of the soil so if conditions dry you are just compounding the problem.

Watch the Video See Aerators

Raking & Scarifying

Raking out moss if grass growth is good will help your lawn. Be gentle and keep damage to a minimum as there are zillions of weed seeds now waiting for a bare patch in your lawn! Heavy scarifying for thatch should be left until August or September as the procedure is far more invasive though it is better to do it now if you weren't able to do it last autumn.

Watch the Video See the Scarifier

Repairs & Renovations

Renovation requires water to help the grass repair and recover so only undertake renovation if you can water if conditions are or become dry. Any seeding or turfing done after this month will require regular watering or rain to establish.

Pests & Diseases

Spring is often a disease free time for lawns with red thread only occurring as humidity levels rise from May onwards. This means that if it warms AND rains you could be in for an outbreak. High nitrogen levels reduce the severity considerably so a good dose of fertiliser should be applied at the first signs.

Dry weather and therefore drying soil will make fairy rings, dry patch and dry soil conditions more obvious. If your lawn has these conditions a wetting agent such as YUCCA WETTA will go a long way to reducing the severity of the problem enabling good grass growth.

Chafer Beetles may also start to be seen around the garden. A very common insect throughout the UK and Europe hatching in May to June - hence the name June Bug! If you see large numbers have a read of our Chafer Grub advice as this may indicate a forthcoming lawn problem. Unfortunately, there are now no pesticides available for the control of chafer grubs in the lawn and we've yet to hear from anyone who has had success with nematodes.

View Yucca Wetta

Rolling the lawn

Consider this appropriate for the finest of lawns to consolidate any areas raised by worm activity and frost heave. Do this any time into May on relatively firm ground. Please note that rolling will not level a lawn, top dressing will.

Top Dressing

Top dressing is an advanced lawn care procedure to reduce thatch and smooth the lawn surface. If you are not a lawn nut then I suggest you don't need to bother!

If you are, then as soon as you've got some good grass growth lower the mowing height and get your first top dressing done. Application rates and frequency will vary depending on your goals and type of lawn so please read our top dressing advice.

The New Lawn

With dryer months it may be wise to put this off until autumn unless you can water the area regularly. Having said that, the warmer temperatures are great for germinating grass seed but you do need daily watering or rain.

View Grass Seed Blends

Lawnsmith Products from this Diary:

Thanks for visiting the Lawn Diary

Have a great month


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