Repairing Burnt Summer Lawns
Scorched, burned or brown grass is quite a rare summer event but as weather patterns seem to produce longer spells of wet, cold or dry then this may become a more common event. Read on to find out how to repair a brown lawn to its previous magnificence and maintain a greener lawn for longer next year.
What is the Cause?
You may think that's a daft question after your lawn has suffered temperatures in excess of 30 degrees and no rain for months but other factors will affect your lawn as follows:
- An old lawn will dry faster and suffer more than a new lawn, so is your lawn over 20 years old? If yes read this
- A closely mown lawn has shallower roots and will go dormant and brown sooner. If you mow below 3-4cms read this
- An underfed lawn will not have the resources to cope with drought. If you haven't fed your lawn in spring then read this
- Aeration improves air and water retention in the soil. If you haven't aerated your lawn read this
A Stitch in Time .........
About the only thing you could undertake during the heat is watering , applications of wetting agent and spiking the lawn to allow water and rain to penetrate. Using lawn sandals, rolling aerators or a garden fork you will only be able to prick the lawn surface initially due to it being very hard. Applying a wetting agent next will assist water to penetrate, reduce run-off thus improving water usage and reducing wastage. Water or wait for rain and spike again as the surface softens. You can't over do either at this stage.
The reason for doing this is that you don't know if the lawn is dead or just brown. Leaving a brown lawn for an extended period may mean it really is a dead lawn. Trying to revive it may save you a lot of time and expense later on!
Recognised Revival Routine for Brown Lawns
Most times when you start to water a very hard dry lawn water just runs off and it takes forever to start getting it wetted. You may be familiar with trying to re-wet a dry hanging basket - really difficult! For the fastest results without wasting water read How to Revive a Hard Dry lawn.
Brown Grass vs Dead Grass
They tend to look very similar and the only way to tell which it is is to add water. Dead grass is dead and like anything dead it can't be reversed. Brown grass (not dead grass) is in a dormant state and can be brought back to life. It generally takes a couple of inches of steady rain to start the process of greening after summer drought and then in a week or so you should know where you stand. Unfortunately you may find that even though most of your lawn revives it may be patchy and thin in areas. If you're lucky and end up with total recovery all you need to do is four things:
- Keep the mower on a high setting until the middle of next spring
- Give the lawn a generous feed with autumn fertiliser so that the grass re-builds depleted carbohydrate levels before the winter
- Spike the lawn to ensure penetration of further rainfall. Initially the lawn will be hard but even pricking the surface will help
- More spiking - you can't do too much
- Next year vary your mowing height
If not then read on........
Do NOT Neglect Dead Patches
Hoping for the best once the rains have started may well cause you a lot more work in the future. Some dead areas may remain dead with an unsightly mat of brown grey grass which will not decay and thus prevents grass growing back. Yet other areas where the grass is thin or bare are a target area for weeds, weed grasses and moss. Once established they create even more work so you need to repair all areas with your chosen grass seed before problem plants take over. A stitch in time saves nine is a very apt expression in this case.
Coarse Grasses and Weeds
You may find some unwelcome plants have started to establish during the drought. Some coarse grasses from fields and the countryside may have survived and prospered as they are deeper rooting than your lawn grasses. Similarly, some weeds with deep roots will also be more obvious. If this is the only problem you have then it would be best to dig out the grasses and spray or manually remove the weeds. Though scarifying is often a recommended control for weed grasses it is just that - control not removal! In this case the weed grasses should be young and just single plants or small tufts. I use an old kitchen knife to cut into the roots without too much disturbance to the lawn. Knock off any soil from the roots and you shouldn't have a hole either. Any bare patches bigger than your palm will need a light sprinkling of grass seed.
If your lawn also needs repairing and over seeding, DO NOT use any weed killer as this interferes with the seeds. Dig out the weed grasses and any of the larger weeds, follow the repair process below and live with the remaining weeds until spring next year.
The Repair Process
This is no different from giving the lawn a good rake or scarify as you would for moss or thatch but with the addition of aeration by spiking. Do NOT hollow tine as this has the effect of increasing the rate of evaporation (drying) which is the opposite of what a lawn suffering from drought needs! So, scarify to clear away dead material, expose the soil, spike, top dress if you wish, though not essential, then put in your chosen grass seed and fertiliser in that order. You can follow the procedure either by watching the videos or by reading starting with the page 'How to Rake and Scarify'. If your lawn also has a moss problem start from the page 'Moss Removal'.
Dry warm weather makes for testing conditions particularly if it has been dry for a period of time before seeding. This means there is no moisture in the soil and therefore any watering you do is gone in minutes. This is why we suggest building a reservoir of moisture in the soil prior to seeding. This can mean watering with a sprinkler for a couple of hours in any one spot.
The seeds need to be kept continuously moist or damp for about 24hours to flush out germination inhibiting enzymes within it. Unfortunately, light watering 2 or 3 times a day just means it goes through a cycle of wet, dry, wet, dry throughout the day which doesn’t get rid of the germination inhibiting enzymes. You can help the situation by:
- Building a reservoir of moisture in the soil by heavy watering before seeding
- Cover the area with a thin layer of polythene (available quite cheaply from builders merchants) to prevent evaporation. Remove once the seedlings are 2-3cm high
- Soaking the seed in a mesh bag (a pair of tights will do) for 24 hours. Unfortunately this makes the seed hard to spread so is only suitable for small areas or patching
- If in doubt about moisture levels try the moisture test below
Finally make sure you feed the new seedlings. Use the Starter fertiliser if you're sowing a new lawn or the Autumn fertiliser if over seeding. It's convenient to apply them at the time of seeding but with the changing climate we now suggest feeding within 4 weeks of germination.
The Repair Timescale
Our rule for all treatments to the lawn is 'only when it is actively growing and there is moisture in the soil'. Start too early and you may increase the damage. So, no repair work should be undertaken during heat and dry weather. This means repair is anytime from the first autumn after the damage ideally when things cool down and the rains start. Repairing in the same year as the damage is better and easier than repairing the following year.
Should the worst happen with rains and recovery coming very late in the autumn you may not be able to rake or scarify and over seed before it gets too cold. In this case ensure a generous feed with our Autumn fertiliser followed by a feed of our Winter Green fertiliser early in the new year plus as much spiking as you can manage. This will give the lawn the best chance of surviving the winter, keep it looking as good as possible thus allowing you to postpone raking or scarifying until spring.
Keeping a Greener Lawn for Longer
Good lawn care practices have always been the backbone of maintaining a green healthy lawn and it is no different here:
- Match the mowing height to the conditions
- If watering do it the right way to improve grass root depth
- Maintaining good fertility helps grass tolerate heat stress and develop deeper roots
- Aerate the lawn to keep the lawn surface open to showers - solid spikes not hollow tines
- If your lawn is naturally dry or a burned summer lawn is a common event for you try over seeding with a drought tolerant grass.
The Drought Tolerant Lawn
Technically there is no such thing but a grass that has deep roots will tap into water deeper in the soil thus staying greener longer; at least long enough to survive a typical British summer. That is all true when using drought tolerant grass (deep roots) to establish a new lawn. Over seeding an existing lawn is a different ball game altogether.
For starters, when over seeding only about 25% of your newly introduced seed survives so if you over seed at the new lawn rate you've still got 75% original none drought tolerant grasses remaining!! This means you need to over seed for 3 years running to effect a desirable change!
Secondly it is all very dependent on the condition of the established lawn. If it is old, never been aerated, heavily used or heavily compacted then it's water holding capacity is perhaps 20% of what it used to be as a new lawn. Healthy soil contains air spaces; it is these spaces that fill and hold the water when it rains. Compacted soil has minimal air spaces so no water holding capacity! Solving this will solve 90% of your lawns drought problems. Adding a drought tolerant grass is the icing on the cake.
Also see Compaction
Lawn Moisture Test
You could dig down into the lawn a few inches and check for moisture but a crude and reasonably accurate measure of soil moisture for lawns other than those on very sandy soil is to use a 6" phillips screw driver. If it pushes all the way into the lawn easily then you should have good moisture in your lawn. As the lawn dries it will get harder and therefore the screw driver will not penetrate as far. If the driver won't go in more than an inch or so then your lawn is starting to become dry and care should be taken. Any less than an inch of penetration and I'd classify the lawn as dry and therefore refrain from treatments.
Dry Patches or Fairy Rings
What we're talking about here are patches of dry grass or rings of dry brown or dead grass in otherwise green lawns. These conditions still occur in dry weather but usually occur most years in certain lawns after only short periods of drought. This is more a lawn and soil problem rather than a climate problem and is something that you can quite easily address by using a wetting agent. Have a read of the page on Dry Patch or on Fairy Rings.
Your Essentials for Lawn Recovery
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After you've got rid of the moss from the lawn with your rake or scarifier it is important to sow seed all over to speed recovery and thicken the grass.
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