Hi All,

A very late and slightly abridged blog this week, it took me 3 hours to type the first 2 words because I was prepping all the very useful data that’s been sent in, so thanks to Aine, James, Paul, Wendy, Adrian and Sean, it’s both invaluable and appreciated as hopefully you’ll see later down the blog.

Last week I said I couldn’t see a consistent signal for warmth and here we are sitting in the third lovely warm day on the trot, so it shows how tricky forecasting is because the only 3 things I got right about Easter were that Good Friday was a wash out, high pressure will be in charge and it’ll be dry and getting milder, but I didn’t say warm, so hands up I didn’t see the warmth building as much as it did. That said I’m very happy to make this type of mistake because you don’t moan as much as if I said it’ll be dry and it yaks it down  🙂


I get a number of comments most weeks on this blog and again I really appreciate your feedback, but one thing I ask, no product or company names please because it isn’t an advertising portal for product, be that someone else’s or the company I work for, for that matter. The aim of this blog is non-commercial, sharing of information within our industry, full-stop.

Imitation is the best form of flattery they say..

Whilst I’m on the subject of content, as you know I’m very happy for you guys to reproduce anything I put on the blog, whether it’s circulating it to your club or linking to it, no problem there. For the trade though using the data I publish is a no no, so when I see other companies using the GDD data I’ve collated, I’m not chuffed. Either pack it in or acknowledge where you nicked it from, you know who you are….tut tut.

General Weather Situation

Ok, whinging over…..

Kind of a short one today because we’re already half-way through the week so I’ll really focus on the end of this week and the outlook because our weather is set to change.

Looking at Thursday and Friday for that matter we have another two cracking days, almost a shame to be sat inside isn’t it when everything is looking so fresh and the sun is out ?

So on both days we see early morning cloud cover burn off through the morning to give plenty of sunshine and temperatures probably peaking on Friday in the high teens and possibly low twenties in the Costa Del Sud of the U.K (Andy R please wear a hat and use your factor 30 down in the sunshine capital of England 🙂 ) As intimated above we have a change on the way and that takes place overnight Friday into Saturday morning when cool air pushes in from the north-west. The two graphics below highlight the temperature change from, Friday to Saturday.


Maps reproduced courtesy of Meteoblue

Close of play Friday then we see some light rain and cloud cover pushing into the south-west of England and Wales and moving north to affect north-west England later into the night and Scotland early doors Saturday. As we go into Saturday morning that cold air pushes in and brings wintry showers to north-west Scotland and a big drop in temperatures. Further south it looks sunny again but feeling cooler as the winds freshen. That rain lingers over the north-west coast of Scotland and Ireland for Saturday, elsewhere it’ll be bright and sunny with a strong / moderate westerly / north-westerly wind. Sunday looks like being a much wetter day with the arrival of rain, some heavy into west Ireland and Scotland during the morning. Through the day this sinks slowly south but the heaviest rain may affect Wales and the north of England, further south and north it’ll be dry and bright again until later.

Weather Outlook

So how are we set for next week ?

Well not bad really depending on where you are located, as that low pressure slinks away over Monday we start to build temperature again, particularly in the central and south of the U.K. Further north, a new low will bring cooler, windy, unsettled conditions and the risk of rain, some of it heavy, through Monday to Wednesday.  This rain will be chiefly confined to north-west Ireland, England and Scotland, with it staying dry and warm further south. As we approach Thursday we begin to lose that warmth with the winds switching round to the north / north-east. High pressure looks to stay in charge though so turning dry, but cool for the end of next week.

Agronomic Notes

GDD Data – End of March

Thanks to Wendy for putting this together, this is how we compare year on year till the end of March. Aside from the long winter that included March 2013, March 2015 shows the lowest GDD total since we began charting this in 2010.


So the data confirms a slow start to the year, but because it’s been drier on the whole I think many people will take this over a milder, wetter spring when we have growth surges and poor cutting conditions causing lots of clippings.

Looking across the U.K from 3 sites we can see that the poor spring GDD totals y.t.d were mainly due to a period of non-existent growth between mid-January and the end of February, that’s when the tracking of the cumulative GDD is flat in nature. (see below) You can clearly see when we got growth in March and the burst of growth at the very tail end of the month because all 3 traces show a sharp incline indicating good daily GDD totals.


I also charted the data from Ireland (Cheers Aine) and the differences across Ireland are quite marked particularly in the far south west (Valentia) where the milder (and wetter) airstream means it always gets off to a better start than the rest of Ireland.


Aside from Co. Kerry, we have Cork next up in terms of highest GDD total across Eire, followed by Wexford (Johnstown Castle), Gurteen (Co. Tipperary), Dublin and ClareMorris in Co. Mayo, the lowest of the 6 locations in terms of total growth for the year to date. To put it in perspective Valentia achieved the same GDD total on the 11th of February as Dublin did on the 31st of March !, that’s some difference across a country. Comparing to the same point in time with 2014, Dublin, Wexford and Claremorris are behind last year, Cork is ahead and Valentia and Gurteen are pretty similar.

Warm days and cold nights don’t equal good growth on fine turf…

A statement of the blindingly obvious you might say, but I’ve tried in this week’s blog to put some science behind it and analyse how this type of day actually relates to grass growth or more precisely the potential for growth. Using hourly temperature data from the 6th and 7th of April, (cheers Sean) I charted this out against GDD, so we can see how each hour relates to actual grass growth. (see below)

GrowthProfile060415 GrowthProfile070415

The first fact to highlight is that although these days hit a maximum air temperature of 17.6°C and 16.3 °C respectively, the average air temperature for the 6th and 7th April was 7.6°C and 7.3°C respectively, because of the cold nights. (-0.2°C and -1.7°C)

If we look at the growth profile in green that shows GDD, we know that once this hits 10 we have good growth and you can see that this occurs for 5 hours on the 6th and only 4 hours on the 7th, so really good growth is limited to this time. That isn’t the whole story though because although at this point it’s warm enough for good growth, the plant is experiencing reasonably high E.T stress (we’ll be nudging a daily E.T total of 4mm by Friday I reckon) so this will be growth-limiting, as will daily wear and tear, which also peaks during this time period.

So the maximum potential for grass growth is only present for about 4-5 hours of a given 24 hour period, when we have a combination of cold nights and warm days.

The handbrake for growth in the spring is often low night temperatures and this is the case again in 2015. If we plugged in a minimum night temperature of 10°C, the GDD is positive for a 24 hour period and granted the grass plant won’t be photosynthesising 24 hours a day because of light availability, but you can clearly see the difference in hours of the day growth is possible.



Very dependent on which part of the country you’re in because we have a good window this week for foliars, with the warm air temperatures during the day facilitating good response and bypassing the cold soil. Come next week, the north of the U.K and Ireland will be wetter and unsettled, whereas further south up until later on next week, foliar’s still remain a good choice.

Early Spring Stress


As you can see from the Meteoturf module on Headland Weathercheck (set up for my home location), the forecasted weekly E.T loss from today is 17mm, which is much higher than of late and indicates that areas will begin to dry out quite quickly now, particularly in the surface. So it’s a good time to make sure that moisture is uniformly distributed through the rootzone by making your wetting agent application  and ideally I’d be mixing in a biostimulant because it helps the plant when we go through this type of period. (Assuming they’re all tank mixable that is)

Pathogen Activity

With the warmth in the day and some moisture late last week it’s no surprise that some Microdochium nivale is waking up for its first spring cycle and so I’ve had reports of copper blotching on greens, not scarring, but just sitting there. Fortunately the dry outlook should knock this on the head, but it may be more of an issue in the north and Scotland where more moisture is expected. If you can generate sufficient growth, you can grow it out, but as I’ve explained above, when we have cold nights, this isn’t always possible.

Ok that’s it for this week, normal Monday blog from next week.

All the best.

Mark Hunt