May 5th, 2026

Hi All,

The month of May is I think one of the most beautiful months of the year in terms of the countryside. The verges are in full flow with Cow Parsley (Keck in Leicestershire). Campion and Stitchwort fighting for space amongst grass and Nettles. Everything looks so fresh, especially if you were lucky enough to pick up some rain over the weekend. We had 9.2mm and it must be something curious to this profession of growing grass, I had the kitchen door open listening to the sound of the rain falling and that smell of freshness. Every plant in my small garden appeared to be saying 'Thank goodness for that'.

Lots of insects around currently I noted yesterday, as I plied my wears fly fishing at Rutland Water (this time more successfully), lots of buzzers and newly-emerging Crane Fly blowing off the pasture onto the water. This cobweb clearly shows the evidence of how a warm, dry spring is so good for insects, including Butterflies. Saw my first Swifts yesterday, the last to arrive and the first to go of our beautiful contingent of summer migrants, including Sand and House Martins (and Swallows). It's a pity this government doesn't have the courage of their convictions to ban Tick and Flea spray for Dogs which contain the strong insecticide, Imidacloprid. This chemical which we all know from its time as Merit Turf, is still available for use to spray on dogs and then of course the owners take them for a swim in rivers, lakes and the sea, releasing it into the ecosystem and wiping out aquatic organisms. Amazing really when there are plenty of alternatives that don't impact on the environment so harmfully.

Now last week I talked about my hunch that we would see a change in the weather with more rain in the forecast and I am glad to say that hunch looks to be correct. Them there 'Cut-off' low pressure systems play such a significant part in our weather.

GFS 7-Day projection - tropicaltidbits.com

So that 'Cut-Off low pressure system has dragged the jet stream position further south from its dominant April position of much higher over the U.K. A lower jet stream position means it opens the way to cooler and more unsettled weather. So you can see how important the role of this low pressure system is and for me, just looking at the long-term projections gives us this clue, long before your forecast app has a sniff of a weather change.

So this week's prognosis is cooler, especially so on Wednesday when the wind turns round to the NW and puts day-time temperatures only just breaking into double figures. Thereafter, temperatures recover but nicely into the higher teens. Now then there is plenty of cloud cover this week, which means night-time temperatures will stay in the 5-7°C range and that means we will have some nice, consistent growth through the week after the rodeo ride of April (more on that later).

As we move towards the weekend, we will see low pressure begin to push rain into Scotland from the west and then a southerly-orientated low will drift in over the weekend to bring much-needed rain to the southern half of the U.K. See how it fits, a lower jet stream position means more potential for southerly rainfall. As this low pressure drifts off into The North Sea early next week, its trailing edge will pull down those NW winds again, so we look to stay cooler and unsettled into next week, with more rainfall for all areas throughout the week. Now just a mention of the fact that at the very end of the GFS projection (ECMWF not updated yet so can't use), it is showing high pressure and warm / hot temperatures building from the 17th, 18th May onwards. Now it all could change, but one to keep an eye on. For Denmark, after the commencement of summer last week, this week and indeed next (at the moment) seems to offer similar weather to the U.K & Ireland, sunshine and showers, with nice night-time temperatures to ensure consistent growth. A tonic for them after the very long winter.

April temperature & moisture stats - Prodata Reports - The Oxfordshire, Thame, U.K

Now, I posted these stats last week from my default presentation, but I know they're pretty representative of many clubs / facilities in the southern half of the U.K.

April temperature & moisture stats - Prodata Reports - Ayr, Scotland

Further north, looking up to the west of Scotland we can see a more balanced weather picture from a rainfall perspective, with an almost neutral soil moisture deficit / surplus. Growth though has been as elusive here as it has been across England and Wales with only 10 days (out of 30) conducive to good spring growth here vs. 13 across the south of England, not much difference really and that's because the weather pattern was pretty consistent across all of the U.K temperature-wise.

What lessons can we take from April's extremely high soil moisture deficit and reluctant temperature profile ?

First up, I had a look at the trend in recent years from a rainfall perspective vs. moisture lost from the soil and plant by evapotranspiration and the resulting soil moisture surplus / deficit. The location is my default in Thame, Oxfordshire. Now this is an open site, so the E.T reading is usually higher than a more sheltered, shady site, but we are looking at trends.

Year Rainfall (in mm) E.T (in mm) Soil moisture deficit/surplus (in mm)

2016 56 71 -15.0

2017 6.2 69.8 -63.6

2018 48 60 -12.0

2019 28.2 65.5 -37.3

2020 35.8 92.9 -57.1

2021 14.8 71.9 -57.1

2022 19.6 77.9 -58.3

2023 54.2 62.3 -8.1

2024 72 66.4 +5.6

2025 16.2 86.7 -70.5

2026 6.2 87.3 -81.1

What we can see is the trend for a dry April is pretty strong with only 1 year over the last 11 indicating a soil moisture surplus (the wet year of 2024). If we look at especially dry years, a soil moisture deficit of > 50mm is pretty representative of this situation. Over the last 11 years, we have had 6 years that met this criteria.

So 1 out of every 2 years is typically dry for April.

What about growth ?

For the same location I graphed out the total monthly Growth Potential for April to see if there was a trend. You know The Met Office keep going about the trend for warmer spring temperatures. So can we see a consistent, upward trend ?

Well, no we can't see a clear, consistent trend from the graph (well I can't anyway). To be fair it is only a very small dataset, I'd be intrigued to look further back. The reality in recent years is that April is not a good growing month. Just take this year. A total monthly G.P of 12, divide it by 30 days and that comes out as 0.4, which coincidentally is the threshold for good, spring growth. So April was a good month for growth if you judge it from this one parameter ? Well that's where figures can be deceptive if you view them as a monthly total. When you graph them out on a daily perspective, the picture becomes clearer, especially if we look at consecutive days of good growth.

When we apply the same daily view to rainfall, we can see how sparse it was in this location. It is clear then that April 2026 was marginal for consistent growth patterns and extremely negative from a rainfall perspective. On most areas away from irrigation, growth was moisture-limited.

What were the key learns then ?

Well for me, it suggests we have to be prepared to irrigate earlier in the year for one.

Then we look at the growth pattern and considering if we have aerated anywhere from mid-March onwards, we would be struggling for recovery without throwing high amounts of immediately-available N at the plot. The smart play is to shift aeration to earlier in the season, if (and sometimes it's a big 'IF') ground conditions oblige. When I am talking about aeration, I mean organic matter removal or dilution, if it is deemed worthwhile. Casting our minds back to some earlier blogs, our growth this year started around February 19th, coincidentally, in 2025, it began on an identical date.

Let's look at the growth and rainfall pattern from January 1st ;

As you can see from the graphs above, the most consistent growth period when we also had good levels of soil moisture occurred from the 19th of February through to the 12th of March. Sure we had better growth days later in March and in April, but they weren't consistent and moisture was lacking. Now one of the consequences of low moisture levels is that Poa annua as a species starts to hunker down, cease tillering growth and divert its efforts into seedhead production. If you are maintaining a mixed sward with a Poa annua component, as most are, it means we can often see the surface integrity become compromised. Taking the height down and light topdressing is a good solution but only if you have sufficient growth to recover from this process. 'Sufficient growth' as we can see from the graph above is a scarce commodity, so that makes keeping the balance tricky, at least until rainfall arrives. Rainfall is a 'double positive' because not only does it bring moisture but also cloud cover, which in turn holds up night temperatures and thereby provides a higher daily G.P. That's why it's appearance is key.

So maybe it is time (if you aren't doing it already) to change from the 'traditional date' of March / April and think out of the box. Some clubs have been doing for it for years and thereby reach this tricky period ahead of the game.

Food for thought maybe ?

All the best.

Mark Hunt