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How and when to water your lawn

Grassclippings - Water WaterWhen and how much water should you give your  lawn during the prevailing hot weather when the thermometer is tipping almost 30 degrees centigrade.

We are receiving a lot of calls about the very same subject, mostly about newly renovated lawns with seed or turf.  One big question is how long to water your lawn for.

Should you water your lawns or not when it is this hot?  Turf grasses are tough old things and so long as you  have healthy and desirable turf grasses in your lawns then they should  be capable of coping with the extremes of drought.

If you have a newly renovated lawn then the investment needs protecting and the lawn watering daily or  every other day to aid establishment of the new lawn. In simplistic  terms - droughts happen when it does not rain for a long time. This  makes the land dry. Lakes, ponds and rivers run low. People have to use  less water when there is a drought to make sure there is enough to  drink. Hot countries often suffer droughts. Strange thing is, we are an  Island surrounded by water......

The BBC Weather web site  details that a drought in the UK used to be defined as 15 consecutive  days with less than 0.25mm rain on any one day, but this regimented  definition was abandoned in the mid-80's after running into problems.  Different organisations couldn't decide whether the drought had ended or not, so it seemed easier if each made their own definitions.

It is far more sensible to judge each drought on its own merits... Not many people mourned for the end of the strict definition, as it was  always coming under scrutiny. If after 20 days there is 0.26mm rain, is  the drought officially over? If there is less than 0.25mm rain for 30  days is that 2 droughts? It is far more sensible to judge each drought  on its own merits and even then it is always hard to determine whether a drought has ended. Hindsight as always is a wonderful thing.

The fuzzy logic of a drought is a bit like a bank account. If you  keep emptying it without putting any money back into it, then the source of funds will dry up. If the water loss from a lawn is greater than the water it receives, either naturally via rain or artificially via a lawn sprinkler, then the water and moisture will dry up, like the money in  the bank account. Pray for a rain shower, I hear you cry!

We are often aware of the number of days that it has not rained, say  in a week, but less aware of the natural evaporation of moisture from  the ground and plants including lawns into the atmosphere. See the Water Cylce. The evapo-transpiration rate will increase greatly on warm sunny days  in June. A typical lawn will lose around 5mm of water from its surface  on a summers day. Attempts of artificially watering with a lawn  sprinkler will only replace around 40% of that 5mm naturally lost so you instantly have a water deficit of 60% on day one. Add the water deficit of day two to day one, and day three to days one and two and you get  the picture.

This is why it is just not worth attempting to water your lawn during a period of drought or semi drought because you will never keep up with the natural water loss/deficit and the lawn will gradually turn brown it it's attempt to conserve water at the roots and crown of  the plant to survive when the rains come. On sunny days with lots of  wind, even if the air temperature is not really high, the water loss  form the lawns' surface will still be great which is why you could  potentially need to water a lawn in April or May, especially typical of  this year.

Turf grasses typically turn brown in dry weather a bit like the  leaves on an Oak Tree becoming sticky in the summer to conserve natural  water loss from the leaves during the process of evapo-transpiration.  Patches of weed grasses such as Annual Meadow Grass, Couch Grass, Colts  Foot, Creeping Soft Grass, Yorkshire Fog, Brome Grass to name a few  react violently to a slight change in climatic conditions such as  periods of drought like conditions and go brown quicker than proper turf grasses used in turf production and lawns.

Our advice is to make sure that if you know it is going to be dry,  kill the weeds and moss in the lawn as they take up valuable water in  plenty of time for summer, fertilise your lawn in readiness of the  summer weather and raise the height of cut of the mower to prevent  maximum water loss. Take a look around as you go about your business.  Peer over your Neighbours' hedges and you will see that the lawns that  are not fertilised, full of weeds, mown too short are already almost  brown. The healthy lawns will always look better and greener during a  dry patch and the lawns that are not out in the full sun of the day too.

If you do need to water your lawns, little and often and check how effective you are actually watering your lawn by getting the gardening knife or penknife out and having a little dig in the soil to see how moist to a depth it is. Set the kitchen timer to around 15 minutes in one position and do not flood it otherwise you run the risk of rotting the turf grasses.

As soon as the rains arrive, wait a couple of days then top the lawn on a high mower setting and fertilise it with a good quality lawn fertiliser to get it back up to speed again. Control any weeds that always appear to do really well during a dry spell, in particular the Clovers and Trefoils.

The use of Wetting Agents is a good practice as they break down the surface tension of water top make water wetter. 

Keep tracks on the weather forecast by visiting The Met Office


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