Lawn Renovation
Following what turned out to be the hottest and driest summer for many years, most of our lawns turned brown, leaving the only surviving green grass in shady areas such as in the shade of the Hall in Tom Quad and in the shade of the Cathedral in the Cathedral Garden.
Normally grass will recover after drought as soon as appreciable rain falls, but this year the heat and lack of water was so intense that large areas of grass died completely and will not recover.
Some people may ask why we did not water the lawns in order to stop them turning brown and dying, the answer to that is that with such high temperatures the evaporation and transpiration rates are so high, that the quantity of water we would need to put on would be in the order of tens (if not hundreds) of thousands of gallons and we simply do not have the capacity to do that on the large areas of lawn that we care for.
There is also the question as to whether using vast quantities of water for such purposes is responsible and sustainable.
Because of this our usual autumn lawn renovations have had to be more aggressive than normal, and with some rain finally arriving we have had to get to work to return the lawns to normal.
Ironically, as soon as any green began to reappear we have had to start ripping it up, the old adage “you can’t make an omelette without breaking eggs” comes to mind and we can’t make the lawns better without making them look worse first.
Various things have conspired against us – the continuing dry weather has made much of the work very dusty and unpleasant to do and caused us to delay some of the processes, we have also been plagued with machinery breakdowns, probably exacerbated by the extremely hard ground.
The process of renovation consists of the following stages:
Firstly, scarification – the process of raking out as much of the dead grass and thatch as possible using machines with vertical blades, we either use a pedestrian machine or a tractor mounted one depending on the size of the area to be scarified.
Ideally, three passes with the machine are made, one straight up and down at the “12 o’clock” position, then two more at angles to this approximating “10 to” and “10 past”. Turf experts agree that passes at right angles are a bad idea, as they would leave little cubes of grass that could break away and leave even more holes.
Secondly, spiking – making hundreds of small holes in the top few inches of the lawns, this allows air and water to penetrate further into the soil as well as breaking up some of the compaction and making holes for grass seed to fall into.
Once again, this is done with a pedestrian or tractor mounted machine according to the size of the lawn. This is probably the most tedious part of the job as the machines are very slow to operate and there is little obvious result of the operator’s efforts.
Thirdly, fertilising. A dose of low nitrogen fertiliser with many trace elements is applied by pedestrian spreader, this will feed the existing grass and encourage the new seed to root in well without producing too much top growth.
Fourthly, over seeding – spreading new grass seed onto the lawns, ideally this is done with a tractor mounted machine that makes small holes and drops the seed into them but annoyingly the machine suffered a gearbox failure early on which we have not been able to repair in time.
Instead the grass seed is broadcast either by hand, or, on the larger areas, with the walk behind fertiliser spreader. The majority of the lawns are sown with a mixture of fescue and perennial ryegrasses, but Tom Quad has a finer turf and the mixture here is of fescues and browntop bent grasses.
Lastly the lawns are gone over with either a dragmat or landscape rake to help incorporate the seed and fertiliser into the existing turf.
Now we hope for further rain and continuing mild weather to get the grass seed to germinate and the fertiliser to release its goodness into the soil, but as there still no forecast of significant rain, it looks like we will have to give the lawns one good water after all, in order to get the grass seed to germinate and get some growth back.
Watering is much more feasible now that temperatures have dropped as evaporation rates are now much lower and hopefully one good soak will do the trick.
Watch the lawns and in a few weeks should all be green and lush again.
Click on the smaller images to view larger versions.
The gallery below illustrates the sequence of activities in more detail.
