How to fix runners growing on lawn after de-thatching?

[Notso]

Hi. Help.   

I de-thatched/scarified my lawn a few weeks ago and now I have all of these runners growing on the surface.

Any ideas on what’s going on and how to fix it?

[MitchellMc]

Welcome to the Bunnings Workshop community @Notso. It's wonderful to have you join us, and many thanks for your question about lawn health.

Have these runners only grown since you de-thatched your lawn, or were they existing runners that have now become obvious after the de-thatching? It sounds like you're suggesting that they've grown since then. 

At first glance, this appears to me to be existing runners and that someone has done a shallow cut over the lawn and damaged/exposed the top of them. They don't appear as new-growth but rather older hardened off runners. Do you usually keep your lawn this short? I'd suggest the best course of action here would be to apply topdress to cover the runners and allow your grass to grow out slightly longer.

Let me mention one of our knowledgeable horticulturalists, @Adam_W, to see if he has some thoughts.

Please let me know if you have any questions.

Mitchell
 

[Notso]

Thanks for the reply @MitchellMc

They could’ve possibly been there before but certainly weren’t growing upwards and on the surface like this.

I did go proper short with the mow (which I was regretting). The grass appeared to be growing back well to start with but then these runners were becoming more prominent on the surface.

Shall go with the top dress - any recommendations on type and coverage thickness?

[Adam_W]

Hi @Notso 
Okay... wee bit of a problem there.

So, what type of lawn was it to start with? Aggressive scarifying or de-thatching should only really be done to couch or kikuyu. In those photos I'm seeing couch and then those runners look to be kikuyu but possibly buffalo.
The process of scarifying basically means you are removing all above ground grass and you are pretty much mowing back to bare soil and then the grass re-shoots from below ground with fresh new growth. Normally you'd only do it if the lawn was becoming very spongy underfoot. The outcome will be very, very bare where the lawn once was and takes around 4-weeks before it will start to look full again.

Less aggressive de-thatching involves raking to remove dead material and that can be done on most lawns use a spring-tine steel leaf rake.
If your lawn was patchy to start with then scarifying won't fix that, you need to treat the other causes of the patchiness such as soil compaction or dry spots in the soil.
Yes, you could top dress, but that's not going to make these other runners go away.
I would recommend that you make sure the lawn is staying suitably moist, apply some hose-on Seasol for lawns and observe. Short of removing the entire lawn I can't see a way to deal with those runners as they look like they will become dominant now.

[MitchellMc]

I'd suggest around a 20mm layer of topdressing and water it well so it penetrates down into the grass @Notso. Wait a few weeks for it to settle and apply another 10mm coat. We want to fill but not smother the grass blades. In the meantime, you can apply some Seasol to encourage growth. As @Adam_W has just mentioned, topdressing won't make the runners disappear, but it will cover them since they are now significantly proud of the soil.

Before laying the topdressing, it might be worth aerating the lawn as the soil appears a little compacted.

What I think is happening with those runners is that they were always there, and when you've cut the lawn so low, it's exposed them. Where they were attached to the ground, they've now been cut and are drying out and curling upwards, giving the appearance of growing up. I've added a crude drawing below to illustrate. I've done the same thing to my lawn several times before.

I'd like to hear more about the issue you were initially trying to address. The runners haven't appeared and become dominant in the few weeks since you scarified the lawn, and I see no reason with time why the lawn can't be returned to the same state or better than it was before.

Mitchell

[Notso]

Thanks @Adam_W @MitchellMc.

No idea on what type of grass it is/was I’m afraid - slightly out of my league here. 

Looking at some examples online, I’d say it was a mixture of couch and buffalo (if that’s even possible?).

The lawn was super spongy underfoot and there were some brown spots/patches occurring. Took a friends advice who suggested a thatch issue and to go with the scarifier - I’ll be asking him to go halves if it’s non-recoverable.

I’ll try the Seasol and a good Aerate while I source some quality topdressing.

Appreciate your time and tips thus far @Adam_W @MitchellMc.

Shall let you know how things go.

Cheers. 

[MitchellMc]

@Notso,

Once you've aerated and then worked the new topdress in over the following weeks, the grass will begin to grow back. I'd hold off on mowing for the time being until we get an idea of the health of the lawn. You'll likely end up with similar patchy areas as to what you had before. These areas need to be oversown with new couch seed. Since you have either Kikuyu or Buffalo in there, you'll always have a mixed lawn. If you don't mind the varying grass blade types, then you should be able to re-establish a healthy lawn with some attention.

Keep us updated, and reach out if you have further questions.

Mitchell

[Adam_W]

Hi @Notso, yes, quite possible it was what we politely call a 'tapestry' with different varieties in there. Most common way that happens in newer lawns is when the existing grass isn't removed properly before laying new turf.

Aerating is a good idea especially if you plan to top-dress. Talk with a landscape supplier about mixes for top-dressing. They will often call them things like 80:20 as that's the ratio of course sand to super-fine organic material.
Important that you don't go to heavy - top-dress, don't bury...
One of these helps with the soil spreading too. For a one-off smaller job the quality of that one should be okay.