How to renovate your lawn

If your lawn has structural faults such as poor drainage drastically uneven or poor soil that you complete a reconstruction not a renovation as the renovation process will only provide short term relief of inhert larger problems.

It is important before renovating to determine the cause or causes of deterioration of the lawn, then carry out a corrective program, otherwise you may have to repeat the process again in another year or two. Faults which can usually be corrected by renovating an existing lawn include low soil fertility, soil compaction, too much shade, undesirable grasses and general neglect.

Now, let’s talk about Thatch. Thatch is the build up of living and dead runners on top of the soil. Throughout the life of a lawn, new runners will grow and the old runners will die off underneath the new growth. As you can imagine, after a while this can build up quite a thick layer. 

All lawn varieties can build up thatch from time to time. A small amount of thatch can be beneficial as it helps prevent evaporation, aids water retention and can give increased tolerance to wear and tear. 

However, when this thatch accumulation reaches a point where it impedes water, air and fertiliser penetration, then it needs to be removed by scalping the lawn. 

Before considering a renovation it is necessary to determine what elements of a renovation are required for your lawn. The way to determine this is to use our key below and matching it up with the processes. The processes are listed in the order you will need to do them. If in doubt then scalp, core, topdress and fertilise

Spongy lawn with lots of old growth- Scalp, topdress, fertilise

Thin lawn with hard soil- Scalp, core, topdress and fertilise

Thatchy and spongy lawn- Scalp, scarify, topdress and fertilise

Healthy lawn with hard soil- Scalp, core, topdress and fertilise

Thatchy not compacted lawn- Scalp, scarify, topdress and fertilise

There are also some “renovation” processes that fit into the light and frequent category, if you belong to the next level crew you may be trying some of these frequently to reduce your need for a major renovation.

Reducing laterally lying leaves- Verticutting

Increasing density of turf- Grooming

Scalping is the easiest form of renovation because you most likely already own the tools required for it. This makes it a great process to trial. You can complete the process using your lawn mower by mowing the lawn and lowering the mower on each subsequent cut across the entire area until you have removed all signs of green growth & the entire area is brown.

The main reason for scalping a lawn would be to remove old yellow hard growth and allow for soft new green growth.

It may take a few attempts to get the right amount of scalping for your lawn but a good rule of thumb is be super aggressive on kikuyu and couch, less aggressive on Blue Couch and Buffalo and gentle with cool season grasses (unless you are choosing to thicken by oversowing as part of the renovation).

Pro tip: The browner, dirtier and dustier you can get your lawn when scalping, the better! 

You may need to lower the mower and cut your lawn 3–5 times (or more) in the one session (this can be done on the same day). You do not want to lower your lawn mower too much on the first cut if your lawn is long as this will clog the mower and be difficult to cut. 

The best time to carry out this procedure is from October – December on warm season grasses and September – October on cool season grasses.  Scalping should be done every 2-4 years depending on how much old growth has built up.

Lawns are heavy traffic areas and frequently become compacted. Nutrient intake is impaired, grasses die off from water-logging in winter, and scalding in hot weather.  The lack of deep irrigation reduces root depth and the lawn becomes less tolerant to drought or infrequent irrigations. Weakened turf grass is also more susceptible to a number of diseases. 

For heavily compacted soils, coring needs to be undertaken. This can be done by hand on small areas or a coring machine for medium to large areas. A corer should be set to remove approximately 8% of the surface material, anymore will create instability in the soil surface (particularly on sandy soil) and less will reduce the results.

A core should be taken of approximately ½ in. in size or larger and down to a depth you want your roots to grow, this would be about 7.5 – 10 cms.

All hollow coring should be followed by topdressing with a soil that is moved into these holes to prevent them from compacting again. These holes allow water to penetrate down into the root zone, while at the same time providing adequate drainage.

Pro tip: To break up your cores consider using your mower with old blades and no catcher to turn the cores into soil. Also consider using some of the cores in bare areas to encourage new growth in that area.

Scarifying is the ultimate in thatch removal but does little in the way of decompaction. The easiest way and particularly valuable for cool season grasses is to grab a steel rake and rake the surface removing the dead grass between plants. For warm season grasses though you will need to conduct this with a machine.

Scarifying can almost be described as vertical mowing, where the blades move in a vertical fashion rather than your usual horizontal mower. As such the blades are cutting into your lawns surface. What makes scarifying blades unique is they have a hook on the end for pulling thatch out. The blades should be set all the way through the thatch, the easiest way to see this is when scarifying their will be a small amount of dirt coming from the machine as the blades go through the thatch and hit the soil. A scaryfing height can be anywhere between -5mm to -20mm depending on thatch.

Use your mower to remove the scarifyings do not leave them hanging around. Remember to use old mower blades for this part.

Top dressing is utilized for smoothing or levelling turf as well as filling holes produced by coring.

Top dressing soil should be clean, free of pests and weeds, and be of a good medium sand or a loamy sand like 80/20.  Spread the soil as evenly as possible over the area and rub in using the back or a rake, broom or ideally a level lawn.

Now that the topdressing is rubbed in its time to bring back some of that leaf and the best way to do that is with a readily available nitrogen fertiliser like Munns Professional Golf Course Green or Munns Professional Buffalo Booster. Then water it and watch that lush green growth return.

Now these ones have just come in as a side note. They aren’t common practice unless you are talking highly managed turf as they require more tools and high frequency. These 2 process are about light and frequent “teasing” of the grass.

Verticutting involves exactly as the name suggests, vertical cutting but unlike scarifying you are not going through to the soil, a typical depth would be -3mm to -5mm. The verticutting blade has significantly more blades than a scarifier and are closer together (do not use a verticutter for scarifying as you will destroy your engine). The purpose of verticutting is to cut the growing parts of a stoloniferous grass like bent and couch to promote more growing points and increase density.

Grooming is very similar to verticutting except with this process you are even higher, the blades this time is aimed at the leaf blades of the grass that are lying horizontal and aren’t being cut by your other mowing, typically -1.5mm to -2mm. It’s not uncommon to have a grooming reel attached to the front of the mower on highly managed surfaces, completing both tasks together. That truly is light and frequent!