Should you water your lawn and if so by how much and when?
Well here I am, sat here near Cambridge, about to write an article on watering your lawn and its chucking it down outside - makes you realise that there are very few occasions when you have to water your lawn for drought reasons in the UK!
Should you ever water your lawn?
No doubt a few years ago we had several summers where there were extensive periods of dry weather. Many peoples lawns went very brown and looked as though they had died. Water companies imposed hosepipe bans and so you couldn't water your lawn even if you wanted to. So, are we all now a nation without lawns? Well, no, the vast majority of lawns recovered fine - grass is a very hardy species and while it takes some care to look at its best its quite difficult to kill by abusing it.
When should I water my lawn?
If its legal to do so there are a few occasions when you may want to water your lawn and some circumstances when it is highly desirable to.
- Some types of slow release lawn feed require that the lawn is watered after application.
After moss killer
- Dry powder forms of moss killer (ferrous sulphate) require watering after application.
- In order to bed the seed well into the soil its required to water the lawn well after application of extra grass seed.
After Aeration, Scarification
- After these processes have been carried out on the lawn it is strongly advised that you water the lawn in order to allow the grass to recover properly.
During a Drought
- If the lawn starts to go brown or gets a faint blue tinge this is a sign that the grass is in distress and would certainly benefit from the occasional watering. This is likely to happen only for a few weeks a year - in a hot summer! Don't water the lawn at the first sign of hot weather as it doesn't need it.
Morning or evening
- The best and most convenient times for people are to water your lawn either early in the morning or later in the evening. This reduces water lost through evaporation and aim for periods when the heat of the day is absent.
How often should I water my lawn?
For most things in life little and often is appropriate but not here. That would encourage the grass to develop a shallow root system. This will mean it will not be able to extract enough water in dry weather and hence need more watering!
Aim to water your lawn infrequently but each time give it a good soak. This will encourage a deeper root system meaning it will better tolerate drier conditions and need less watering in the long run. During a hot summer grass can need anywhere between 15-25L of water per m2 to replace the water it has used in a week. If you watered your lawn each week that's an awful lot of water and ultimately you will end up with a weaker lawn.
How to reduce the amount of watering a lawn needs
- Cut the grass to a longer length than you would normally do. Reduces the amount of water loss.
- If you do water soak it infrequently
- Aerate the soil to allow the roots to penetrate deeper and will also allow any water on the surface to soak into the soil rather than run off the lawn
- Scarify your lawn to reduce the amount of thatch which absorbs any rainfall/watering before it can get down to the root system. The water stored here is more likely to evaporate.
- Don't waste water
- Check the 7 day forecast for rain to see if you really need to do it
- Don't water garden paths and walls. Position the sprinkler etc so that it goes on the lawn and no-where else.
- Don't forget about the sprinkler being on! An hour in one location should apply about 15L of water per m2 depending on sprinkler coverage. So don't leave it on all night.
What equipment is needed to water my lawn?
There are a few options
- Tiresome but could be used for the odd spot that has maybe been repaired but not practical for a large lawn that needs 15L per m2!
- Cost ~ £5
- Better and a good reason to get out of the house for some time alone but can still take a while to do a whole lawn with the required volumes of water needed
- Cost ~ £15 for 50m length. Wall mounted retractable units (which are very good btw) are more like £60 for 40m.
- Ideal as they can be setup to water large areas unattended and many can be restricted to only do certain directions which lessen the amount of water wasted on paths, driveways etc.
- Cost ~ £15 plus hosepipe costs
Automated watering systems
- Make sense on a golf course where the green needs watering in hot weather as the grass is very short and green keepers have a lots of grass to care for. Perhaps a luxury for the average householder - and with good lawn care unnecessary.
- Cost ~ £90 plus time to dig channels for piping etc.
How much does it cost to water my lawn?
If your house has a water meter then you will be charged for the water used. Let's estimate that.
First assume your lawn needs anywhere between 15-25L per m2 every time you water it. Using a figure of 100m2 of lawn that is 1.5-2.5m3 of water. With Anglian water that will cost £1.29 for the water used and £1.42 to dispose of it (they assume 90% of used water goes into drains the 10% missing is for stuff like this watering gardens etc).
- These figures mean it costs between £3.9 and £6.4 to water 100m2 of lawn.
As a check lets look at it another way. I measured the output from my 40m hosepipe at 0.2L per second (took 10seconds to fill a 2L bucket). Assume you have a sprinkler that can do your 100m2 lawn in two positions say 50m2 of grass each. A typical figure for me would be to leave it on for an hour in each position (feels about right).
That's 720L of water in one hour or 14.4L of water per m2 - about right.
- That would cost £3.70 per 100m2 of lawn.
This is another reason not to water your lawn to regularly!
- Water after mechanical treatments like aeration/scarification
- Water after applying over-seeding, slow release feed, dry powder moss killer
- Never water your lawn little and often. Soak it infrequently to encourage deep root systems - which are then more drought tolerant.
- Watering a 100m2 lawn costs about £4 in water charges.
A lawn is like a child if you constantly give it attention it will keep demanding more and never learn to stick up for itself. Get the basics right and it will be strong enough to keep going in the dry times as well as the wet.