The weather throws many curve balls at our gardens, one year it’s drought, the next it’s excessive rainfall resulting in floods. It can be Difficult deciding when you need to mow, what you need to do to bring it back to its prime etc etc. So, here is some information on what’s going on within the plant and soil and how to help your lawn not only survive but flourish.
What is a Saturated lawn?
Now a little rain never hurts anyone, but a lot…. Well, that’s a different story. To start, it’s important to point out that we are talking here about a day of heavy rain. We are talking prolonged rainfall. The best way to describe it is to talk about a saturated lawn.
Most people are familiar with the term saturated, but if we wanted to get technical, for soil this, simply means that every void/space within the soil is filled with water (before gravity starts to take it away).
As a result of nearly all your lawns pore space filled with water, this has many impacts on your lawn.
What happens within a saturated lawn?
Sadly, it’s not very pretty. The roots of our lawns breathe through the soil and if they can’t breathe then things start to go backwards in the soil:
- Loss of air spaces in soil
- Reduced root respiration leading to root death
- Loss of nitrogen from the soil
- Negative impact to soil biology health
- Loss of soil structure
- Poor infiltration of new rainfall
Without a proper functioning soil then we suddenly have some negative things happening on top of the soil:
- Reduced photosynthesis, both from cloud cover and due to lack of root respiration
- Increased chlorosis (a fancy way of saying yellowing) of the lawn
On top of all this, we start to have negative impacts of water movement:
- Weed seed moving from nearby creeks and neighbours lawns
- Water sitting on top of the surface
All these things contribute to one nasty experience when your lawn gets excessive rainfall.
Is my lawn saturated?
When we first think of saturated soil, it conjures images of soft, wet mud. A saturated soil for a short period by itself is not a huge concern, however, over time this begins to present an issue. So, before we hit the panic button and run into solution mode it’s important to understand the extent of the damage that’s been done, this will help us put in place the strategies required to restore our lawn to its prime.
To simplify the problem and give the best advice, we have broken it down into 3 different lawn types
- The Wet Feet Lawn- this lawn hasn’t gone under water but some surface water appeared at times
- The Swimming Lawn- this lawn has been under water for less than 2 days, but did go under
- The Submarine Lawn- this lawn has spent 2+ days submerged underwater
The Wet Feet Lawn
A lawn that hasn’t gone under water for a significant period still has its issues so it’s important to monitor and put in some strategies to help restore your lawn.
Firstly, let’s get some air into the soil, this can be done with a garden fork, a hand corer or even get a contractor to help.
A lawn that cannot breathe has endured some stress and with prolonged leaf wetness, makes it a candidate for lawn disease. Monitor for spots on the leaves, if they start to become large in numbers, then treatment with a fungicide like Chlortan may be required.
With excessive rainfall stripping nutrients from the lawn and low light conditions, it’s likely that the lawn will be hungry. DO NOT rush out and feed it to get that colour back, this will only increase the disease pressure and help induce disease. Instead wait until soil moisture levels are more reasonable and apply a foliar liquid (like Lawnganics Brilliance), providing a gentle feed (to reduce risk of disease) and iron + zinc to increase chlorophyll production.
The Swimming Lawn
Having your lawn go under water for a couple of days isn’t that bad. After all, it will come back if you put in the required repairs.
As for the wet feet lawn you will need to aerate, monitor for disease and eventually look to apply a foliar fertiliser application. However, with this lawn you need to consider what may have happened in the time it was under water.
Creeks and dams which overflow in rain periods are notorious for being poorly managed, with weed seed lining their banks – Monitor for weeds in the next few weeks. Even if you haven’t had local creeks break their banks, what do your neighbours lawn look like?
Once the lawn has dried out you should consider an application of a pre-emergent herbicide like Barricade to help prevent some of these seeds from emerging.
The Submarine Lawn
Maybe the Beetles were referring to this type of lawn? Yellow submarine…Sadly, this has been an all too common problem in the last few years.
Ironically, the lawns that are most likely to go yellow in this experience are the faster growers, this means they will also recover faster. So, remain patient and your lawn will eventually get its colour back, but it will take time.
Due to the prolonged period underwater, it is better to take a curative approach to your lawns management, as opposed to a watch and monitor one. This means you still need to aerate, but an application of Chlortan as a preventative and fertiliser, are now more critical to your lawn’s health.
Once the lawn has dried out you should apply an application of a pre-emergent herbicide like Barricade to help prevent many relevant weed seeds from emerging.
When can I mow after rain?
This is probably the most common question we get around rainfall and saturated lawns. ‘Mow high and wait till dry’ is the mantra we use.
Sadly, there’s not much we can do when our lawns are properly saturated. It simply becomes a waiting game, use this time to ensure you have sharp blades on your mower for a nice clean cut. Once any water has subsided, walk across and check for firmness, walk/drive the mower over and see if it leaves any wheel tracks. If it doesn’t, then it’s good to cut when the leaves are dry! It’s important we don’t put the lawn under any more stress by removing excessive amounts of clippings, so ensure you do not scalp the lawn.
Frequently Asked Questions
When can I mow after rain?
This is probably the most common question we get around rainfall and saturated lawns. ‘Mow high and wait till dry’ is the mantra we use.
Sadly, there’s not much we can do when our lawns are properly saturated. It simply becomes a waiting game, use this time to ensure you have sharp blades on your mower for a nice clean cut. Once any water has subsided, walk across and check for firmness, walk/drive the mower over and see if it leaves any wheel tracks. If it doesn’t, then it’s good to cut when the leaves are dry! It’s important we don’t put the lawn under any more stress by removing excessive amounts of clippings, so ensure you do not scalp the lawn.
Can I apply Barricade the moment the water subsides?
No, please follow the label for application of Barricade Herbicide, it cannot be applied to a waterlogged lawn.
I have recently applied a fertiliser, should I reapply?
There is a very high probability that it’s gone, but it does depend on product used and method of application. Wait for your lawn to dry out and see how the colour and growth responds. If the colour does not improve and growth does not increase, then another application will be needed. Just be sure to keep it as a light feed and ideally a foliar.
I applied Acelepryn a few weeks ago, is that all gone?
No. The active ingredient in Acelepryn, chlorantraniliprole, is highly immobile in soils and highly insoluble in water. Therefore, there is no requirement for a reapplication.
Will a wetting agent help move water?
Wetting agents like Lawn Play Aquaturf do help manage water within the soil profile, but as they need watering in, it’s best to keep this for when the lawn has dried out. With sandy soils it’s not uncommon for lawns to dry out in patches not long after, so monitor for any hydrophobic patches developing.
Any other questions? As always, the Lawn Genius is here to help with any lawn problem you may have.
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