May 2021 Lawn Diary
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:
- Weed Control
- Top Dressing
- Repairs and Seeding
Driest and frostiest April for 60 years!
An extremely tough month for lawn care with low temperatures and next to no rain, then lovely drying sun right through to the last week of the month. Some showers about at the end of April and the long range forecast below predicts more variable May weather more ideal for gardening.
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 now temperatures are on the up if there is adequate soil moisture. 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 though regular watering by hose may be needed. So a reminder for watering; you need to keep the seed damp until germinated. If it dries out within a few hours of watering you will stop the germination cycle so frequent light watering is essential.
May Forecast courtesy of the Met Office:
Sunday 2nd to Tuesday 11th May
Showery conditions with temperatures well below average continuing into the start of this period. Each day, showers will develop fairly widely but most areas will also see some decent sunny spells. Nights will continue to be cold with some overnight frosts. Showers are likely to continue to fall as snow over high ground in the north. Into next week, a gradual transition to more unsettled conditions is likely though the timing and details of this transition is uncertain. This brings an increased likelihood of spells of more persistent rain and stronger winds at times. Temperatures are likely to remain below average overall though there are signs that they could recover back closer to average with a reduction in the extent of overnight frosts.
Tuesday 11th to Tuesday 25th May
Confidence is very low for this outlook as is typical of late spring. A mixture of sunny/clear spells and showers, especially likely at first, but an increased chance of more unsettled weather with stronger winds and longer periods of rain arriving from the Atlantic compared to normal. Temperatures probably starting off cooler than average, but will most likely be around to above average overall.
A slightly late start to regular 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.
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 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:
- 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.
- Once the base granular feed is applied you can 'Top-up' with our soluble feed Solugreen as and when required throughout the season
The weeds may also be 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 to get the best 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.
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 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 starting to flower and seed 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. Weedol weed killer is the only weed killer that allows use after 2 months of seeding.
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.
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. Unfortunately, as many of you have learned, summers such as that of 2018 can cause serious damage particularly to older lawns. If you often end up with dead grass patches after dry spells a new lawn might be your best option. Anyway, 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.
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.
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.
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.
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.
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 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.
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.
*Lawnsmith product categories from this diary:
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