We have produced this article in response to the worries of many readers about what effects the torrential rain will have had on their applied fertiliser, what may happen in the short term and how best to fertilise for the remainder of the summer.
Firstly, some of you are probably noticing that you lawn looks pretty good just now. This is not the case for everyone. Those in the areas that have received the heaviest rain have suffered some transient damage, grass is unable to grow if it is drowning or there is no sunshine. The damage caused will not be permanent except in the very worst cases where ponds lay for more than 3 days.
However, the implications of this weather are that the nitrogen, the easiest leached (washed out) component of fertiliser, will have been lost. As the weather returns to normal again, with the readily available water, the plant may well run out of steam. This depends on the types of fertiliser and soil that you have. If you have used inorganic (normal) fertiliser on sandy soils, that will be the worst. If you have been using slow release or organic fertiliser on good quality loams or slightly heavy/clay soils they won’t be affected quite so badly.
We are now at the part in the season when maximum use will be being made of your lawn for football, tennis, badminton, festivals! or barbecues (hopeful thoughts maybe!).
The implications are that you want your grass looking at its best whilst maintaining its resilience.
To do this, don’t overreact to yellowing of the grass by over compensating and applying too much nitrogen based fertiliser. A good tip for this situation is to use an organic or Growmore fertiliser. These are better balanced and slower release. This will also last longer should the rains come down again
Add to the colour of your grass by applying fertilisers pre mixed with iron or add an extra iron sulphate application to your programme. At this time of the year, the plants will be very hungry for the Sulphur element of this fertiliser.
Maximum top growth is now over for a while and the grass is naturally trying to set seed. Those of you that are unable to cut regularly enough will now be struggling with a lot of grass stalks. Don’t worry about this although it will give a disappointing feel under bare feet. These cut stalks die and naturally fall from the plant.
If, at this time of the year, grass starts to yellow due to lack of fertiliser, it is more likely to try to set seed, this being the natural response of the grass plants to stress. Don’t worry about this either. Just maintain a good weekly (at least) mowing regime.
This is important at this stage for a couple of reasons.
Heavy rainfall can seal or cap your soil surface, especially in silt or clay soils. As we have said before, grass roots require air as much as water and nutrition to grow, it is a real key to growing grass. Also if you go and use a lawn after heavy rain, you are more likely to compact the rooting part of your lawn (unless you have utilised products like our rootzone during establishment). I wouldn’t suggest a hollow tine machine at this stage, a basic solid tine (garden fork!) will do. A depth of at least 4” (100mm) should be your target. Let the soil dry out a bit before aerating or you could make matters worse.
You must spread lawn fertiliser using a mechanical method, either a drop spreader or a spinner. Using you hands to spread fertiliser is notoriously difficult. It is almost impossible for you to spread the product evenly. The minor effects are a mottled or patchy look to the lawn and in the extreme case the fertiliser will burn out the grass where it is applied at too high a rate.
My personal preference is for a spinner. I love these small handheld ones, excellent value and ideal for the smaller lawn.
Make sure and not spread too much fertiliser. Measure you lawn area in sq metres and calculate how much fertiliser you should apply. The recommended rate will be on the fertiliser product packaging. In reality, most products fall within the 35g to 50g per square metre rates. So if you lawn was 40 sq metres and it was a 35g per metre product the calculation would be 40 x 0.035Kg = 1.4Kg
This will be your second last summer fertiliser application, targeting your final summer application for the end of August. In September we will turn to Autumn/winter fertilisers and topdressing; however that will keep till later!