A good lawn can really make or break a garden, but for many of us (particularly in drought affected Australia), getting that golf course like green patch has thus far proven elusive. We're here to change that.
The first step to a successful lawn, and any garden plant really, is to put in the time to properly evaluate and assess your site and choose a lawn/plant variety that is suited to the area (think light conditions, rainfall, soil type and drainage, wind exposure, traffic, etc). Taking the time to amend or even replace poor soil will prove a much better investment of your time that sinking countless hours and dollars into attempting to fix problems later down the line that could have easily been prevented with proper preparation.
Despite this however, we suspect the majority of people reading this blog already have a lawn, and are after some pointers on how to help their existing and established lawn, so that is where we will start. "Taking the time to amend or even replace poor soil will prove a much better investment of your time that sinking countless hours and dollars into attempting to fix problems later down the line"
In horticulture, turf grasses are categorised into either C3 or C4 grasses, representing the number of Carbon atoms present per molecule during photosynthesis. Sound complicated? Don't worry, a much easier way to remember the distinction between the two is Cool Season (C3), and Warm Season (C4) grasses. As their name suggests, cool season grasses are better suited to cooler conditions, while warm season grasses are better suited to warmer climates. Here in Melbourne, Australia, we can grow both C3 and C4 lawns, but will find that our C4 warm season lawns will go dormant in Winter, while our C3 cool season lawns can go dormant or die in Summer without considerable irrigation.
A Stenotaphrum (Buffalo) lawn maintained at a higher mowing height, typical of American lawn care providers
The species of turf grass used around the world are pretty common, but often with some variance in common names and maintenance practices (Americans for example often mow Stenotaphrum secundatum lawns much taller than us Australians), so like other areas of horticulture, it does help to learn the universal Latin botanical names of grass species as well as their common names.
Common C3 Cool Season Grasses: Bent grass (Agrostis stolonifera) Bluegrass (Poa pratensis) Perennial Ryegrass (Lolium perenne) Fine Fescue (Festuca sp, usually Festuca Rubra ssp, known as Creeping Red/Chewing Fescue) Tall Fescue (Festuca arundinacea)
Common C4 Warm Season Grasses: Couch/Bermuda (Cynodon dactylon) Buffalo/St Augustine (Stenotaphrum secundatum) Zoysia Zeon/Sir Grange (Zoysia matrella) Zoysia 'Empire' or 'Platinum' (Zoysia japonica) Kikuyu (Pennisetum clandestinum)
A Kentucky Bluegrass (Poa) C3 cool season lawn, common in cool climates and popular for it's deep green colour.
In some ways our intermediate climate is a blessing as C3 grasses will do really well even in our mild Winters, and provided they receive adequate irrigation will still look great in Summer, but on the other hand, our extreme Summers and periods of drought make C3 grasses the inferior choice for many lawns, whereas the popular C4 grasses will go dormant in Winter while the weeds are still actively growing, presenting their own sets of challenges. Knowing your grass variety and understanding the unique challenges of your local climate and micro-climate will go a long way in helping your lawn look it's best.
The second distinction to make is whether your grass has a creeping or a clumping/bunching habit. Of the C4 warm season grasses listed above, all of them have a creeping habit, whereas of the C3 cool season grasses listed above, those with a creeping habit are limited to bentgrass, bluegrass, creeping red fescue (a variety of fine fescue), and a new variety of tall fescue known as Rhizomateous Tall Fescue, or RTF for short. But why does this matter?
Well, creeping grasses can 'self repair', filling in bare patches around them, but also have the ability to be invasive, spreading into garden beds and onto footpaths. This is all valuable information to consider when selecting a turf grass to install, and for those with existing lawns, it can help in understanding their growth, how to deal with bare spots and propagate new grasses if desired, and also to be prepared to prevent unwanted spread into garden beds via rhizomes.
All grasses will 'bunch' and form clumps, but not all grasses will creep and spread. Grasses bunch through the process of 'tillering,' where new shoots will develop from the crown of the grass plant, and mowing will stimulate this growth. Creeping grasses will also spread through asexual, vegetative reproduction through special above ground and below ground stems known as stolons and rhizomes respectively. Rhizomes and stolons will root at sections called nodes, which will then produce new crowns and grass plants. This is what allows some grasses to 'self repair' after damage, but also what causes them to become invasive in garden beds and over paths where other grasses are not.
Understanding these processes, in particular tillering, help us to 'hack' our lawns to promote thicker and healthier swards through our maintenance practices. For instance, if we mow our lawns shorter, we can promote more tillering due to better sunlight penetration, while the act of mowing itself triggers tillering by breaking 'apical dominance' and triggering auxiliary buds in the grass crown to break and shoot. Keep in mind however that mowing low can cause it's own set of problems and is probably the biggest cause of lawn issues on home lawns due to lack of proper understanding of the hows and whys of mowing heights and frequency. More on this later, but for now we need to first discuss the cultural requirements of lawn and turf-grass.
Soil preparation is of drastic importance in any lawn establishment or re-installation project, like this one in Melbourne's North West.
Soil is the most important part of any garden - period. We are now beginning to realise and understand that soil is more than just a medium to grow plants in while holding nutrients and water for the roots to take up. Soil is alive with billions of beneficial microorganisms like bacteria, fungi, and nematodes that convert organic matter into nutrients and soil improving hummus, develop mutually beneficial relationships with plant roots sharing water and certain nutrients in exchange for carbohydrates, and fighting off pathogenic bacteria, fungi, and nematodes. Soil is therefore best looked after organically, to allow us to work with nature and not against it.
When it comes to the kind of soil we want for lawns, there are a few key points. Grass needs free draining soil (so roots can receive lots of oxygen, which isn't possible in boggy ground), which usually means sandy soils, however, some clay and a good amount of organic matter are important to hold onto some water and nutrients, and a soil too sandy will be leached of its nutrients and dry out very quickly. Depending on whether your grass is a C3 or C4 grass, it will usually require either a fair amount of moisture, or will handle mild drought relatively well, respectively, and most grasses can handle poor fertility in soils.Keep in mind however that for a lawn to be lush and green it needs to be actively growing, and this means water, iron, and nitrogen consumption amongst other nutrients. "Soil is the most important part of any garden - period."
Technically, turf used for different purposes should have different soil profiles. Golf courses and sports turf areas need to be incredibly firm and traffic resistant, and companies that manage these sports turf areas typically have the resources to accommodate frequent irrigation, fertilisation, and maintenance, and therefore the soil of these turf areas usually consist of mostly sand with a low proportion of organic matter. Display lawns on the other hand, that usually receive less frequent and lighter traffic, can benefit from increased organic matter in the soil which will improve water and nutrient retention while still having the pore sizes needed to remain well draining and oxygenated. Organic matter, in the form of well aged and sieved compost, is a great addition to almost any garden for it's ability to remedy the downsides to both heavy clay and heavy sand soils, however, high traffic lawns benefit from a firmer, less-prone-to-compaction foundation, and at the expense of high water and fertiliser needs are usually built on the foundation of a much sandier soil than we would recommend for almost any other purpose. To summarise: Sandy, low organic matter and low clay soils for sports turf, and sandy, but with more allowance for clay and a good amount of organic matter for lower traffic lawns.
Golf courses need to be firm and low to provide a consistent playing field and resist slumping. Picture: Agrostis (bentgrass) golf green.
Nutritionally speaking, we would always recommend using organic fertilisers be they solid, liquid, or both as part of an overall nutrition program that includes annual or semiannual top dressing with organic compost. While high nitrogen and iron fertilisers will promote vegetative growth, you can have too much of a good thing. Excess nitrogen is not only a waste of money, but it can harm you lawn in both the short and long run. In the short term, excess nitrogen can burn your lawn, and in the long term, applying too much nitrogen fertiliser, particularly at the wrong time of the year, can lead to excess vegetative green growth at the expense on vital root growth beneath the surface, which can lead to turf stresses later in the season, while leaving the turf far less resilient overall.
What we want to promote is thick, deep, and healthy root growth, to increase water and nutrient availability, increase resilience against pests that feed on roots such as grubs and leather-jackets, and increase resilience against drought and heat stress. Too much top growth and not enough root growth may look nice initially, but will ultimately lead to problems.
A lawn as thick and lush as this Pennesetum (Kikuyu) needs a strong and well developed root system to stand the test of time.
So how do we promote root growth and resilience? The simple answer used to be Phosphorus for root growth and Potassium for resilience, but now we are also learning that these nutrients often become locked up in mineral form that the plants cannot use the majority of, and we end up wasting money and even harming the environment through runoff and leaching. It is true that a higher ratio of Phosphorus and Potassium in a slow release, organic, non water soluble NPK fertiliser (Nitrogen, Phosphorus, Potassium) will improve root development and strengthen cell walls making the turf more resilient, however, this should only be part of an integrated approach that also utilises methods both cultural (such as deep and less frequent irrigation) and biological (inoculating, introducing, and/or promoting beneficial bacteria, mycorrhizal fungi, and beneficial nematodes). By promoting deep rooting with deep watering practice, and promoting a healthy soil ecosystem full of the organisms that make many of the nutrients previously locked up in the soil available to the plants, we can reduce the lawn's needs for irrigation and fertiliser.
Each lawn will have different moisture requirements based on it's genus and species, its soil profile, and its individual microclimate, and therefore it is necessary to evaluate your lawn's performance and introduce or adjust irrigation as required. Some climates are so rainy that you can get away without ever watering your lawn except as a precaution in heatwaves, whereas in drier climates like ours in South Eastern Australia, we have to provide irrigation if we want a healthy lawn, and with many areas living under water restrictions we have to make sure we are also very efficient with our water usage. A good millage to shoot for from combined rainfall and supplementary irrigation when starting out is 25mm a week in the growing season, however, this is just a guide number, and like I mentioned before, each and every lawn's water needs will be different, even at different times of the year.
Aim to provide infrequent deep watering that soaks the lawn and wets the soil up to 6 inches (150mm) deep, and allow the top few inches of soil to dry out before watering again, as this will cause them to travel deeper in search of more consistent moisture. When irrigating any plant or crop, we aim to keep the soil within a certain moisture sweet spot, between what is known as the Temporary Wilting Point (TWP) and the Field Capacity (FC), and never falling below the Permanent Wilting Point (PWP). This can get quite complicated and for the beginner I suggest just watering again as the top couple of inches of soil dry out, but for more advanced gardeners I really suggest looking deeper into PWP, TWP, FC, and SP.
In simple terms, SP or saturation point is the point at which the soil can hold no more water as all of it's pore spaces are full. FC is the amount of water that an area of soil can hold after excess water has drained away and downward motion of water has slowed, while temporary and permanent wilting points are actually measurements specific to individual plants where they can no longer take up water, and begin to wilt, the distinction being wilting that can be recovered from and wilting that will kill plant tissue which can only be replaced by new growth. Some plants are capable of sucking water out of relatively dry soil, but need lots of oxygen at their root zones (drought tolerant, but need well drained soil), whereas some plant roots are not as capable of sucking water out of dry soil (and thus will reach their wilting points in wetter soils) but can handle less oxygen at the root zone (boggy plants than don't mind wet feet). Turf grass prefers well drained soil with plenty of oxygen, but can usually handle drier soil than many bedding plants.
Deep grass roots are best promoted by infrequent, deep watering over frequent, shallow watering.
Before we begin to dive into mowing heights and frequencies, we need to discuss sunlight. The reality is, lawns need good direct sunlight for ongoing thick, lush, and green growth. All the water and nutrients in the world wont help a lawn if it can't access sunlight - that water and those nutrients are only the building blocks to convert the sun's light into carbohydrates, so no sun equals no growth, which equals no thick, green lawn. Some turf varieties such as the Fescues, Zoysias, and Stenotaphrums can tolerate some decent shade and will grow great in partial shade provided they still get a god 4-6 hours of direct sunlight per day, whereas others like Poas, Cynodons, and Loliums really need 8+ hours per day to perform at their best, only tolerating light shade. These rules don't always apply as the many various hybrid cultivars are bred some for shade tolerance and some not so much, but it is important to understand the sunlight needs of the various turf grasses before choosing one for your site, and if you already have a lawn that is getting some shade, understanding your lawn's sunlight requirements can help you make the changes (through mowing heights, irrigation amount and frequency, and potentially even tree trimming) to help your lawn to do it's best.
Now for the man business - mowing! When it comes to caring for residential lawns as opposed to sports turf areas, mowing often receives the most attention, and while there are certainly other aspects of lawn care that need the attention of the home lawn enthusiast and the lawn care provider alike, proper mowing really is a vital part of any turf management program.
Sunlight is the coal, photosynthesis the process, carbohydrates the energy produced, and the blade of grass is the engine room.
The number one mistake when it comes to mowing a lawn is mowing too low all at once. Mowing is not good for a growing lawn, as it causes a lot of stress to the lawn. But what researchers have found is that the stress responses exhibited by lawns when mowed (such as root shedding and focusing most of their energy into top growth to compensate rather than developing strong and deep roots) can be almost completely mitigated if less than 1/3 of the grass blade is cut off in one session. Therefore, based on this 1/3 rule and the optimal height range of our lawn species, we can figure out the mowing frequency of our lawns. Mowing frequency is dictated by our chosen mowing height and how it relates to the 1/3 rule, as we need to mow our lawns frequently enough to keep them maintained to the chosen height whilst avoiding cutting off more than 1/3 of the grass blade at any time. This means that longer mowing heights can create less frequent mowing requirements, and climatic and cultural conditions such as available moisture, nutrients, and sunlight combined with air and soil temperatures will also affect the rate of growth, and thus, the frequency of mowing.
Once you can identify your grass variety, have a look around for it's optimal height range. Buffalo grass (Stenotaphrum) is recommended to be maintained between 30mm-65mm, (although in America where it is commonly known as St Augustine grass it is often mowed to heights in excess of 100mm), and this height range gives us some room for adjusting to meet the site, the season, and personal preferences for the lawn.
We have already touched on promoting a thicker sward through lowering mowing heights, however, this can also create a higher frequency of mowing, lead to stunted root development, increase soil evaporation increasing irrigation requirements, lower the surface area of the grass blades and reduce photosynthesis, and even damage the growth point called the meristem located at the junction between the grass blade and sheath (scalping). On the other hand, mowing too high with allow for more photosynthesis due to longer grass blades, and will better protect the soil from evaporation by shading the soil, but can shade out tillers (side shoots) leading to a thinner lawn with more room for weeds to get in, lead to an excess build up of 'thatch', and can also decrease airflow in extreme cases creating a more hospitable habitat for harmful lawn fungal diseases. Therefore, understanding your chosen turf species - its common pests and diseases, its cultural requirements, and its optimal height range, can really go a long way in determining what height to mow your lawn at throughout the different seasons of the year.
A Stenotaphrum (Buffalo/St Augustine) lawn mowed around the 60mm mark and doing well, far short of the 100mm-110mm mark typical of American lawn care providers.
Typically, we like to focus on thickening up turf with lower mowing in early Spring, increasing mowing height and deep watering intensity (less frequency, deeper soakings) as the weather warms up in preparation for Summer. The mild weather of Spring makes early-mid Spring the perfect time to promote tillering, but we need to remember Spring is also about root development to prepare for the more stressful, drier, and hotter Summer just around the corner. Once Summer rolls around our mowing height should have already been increased to be more water efficient and to promote more photosynthesis to build up energy reserves in preparation for dormancy. Come Autumn, as the days grow shorter and the sun hangs a little lower in the sky, we typically want to continue with the higher mowing height well into Winter, only reducing the mowing height come next Spring, or mid-Autumn should you choose to oversow with a cool season C3 lawn variety (only for C4 lawns) to provide Winter colour, but keep in mind this will impair the Winter colour of your dormant C4 lawn.
"Spring [is] the perfect time to promote tillering, but we need to remember Spring is also about root development"
In a full sun location I personally would avoid pushing the higher end of the optimal range as I don't see it as necessary, and only recommend pushing the upper limit of mowing height in shade or drought conditions (where access to supplementary irrigation is limited). Likewise, in shade or drought conditions, avoid pushing the lower limits of the mowing height for your turf species to avoid excess water loss and less than ideal photosynthesis. Some grasses like bent grass (Agrostis) and couch (Cynodon) with a small range of mowing heights, the difference is more subtle, but with species like the fescues (Festuca) and buffalo (Stenotaphrum) which have a large height range, it really comes down to climate & season, cultural information (site location, sunlight, soil profile), personal preference for appearance, the purpose and utility of the turf area (parkland, formal lawn, fairway, football field), and maintenance schedule when determining the mowing heights.
A high traffic golf fairway needs to be maintained to a much lower height to allow for a good playing surface, but this Zoysia grass is equally happy at 25mm in a front lawn.
While good cultural practises will largely prevent and mitigate the instances of weeds, fungal diseases, and many (but not all) pests, it is important if you wish to have an amazing lawn to learn about the varies weeds, pests, and diseases that are waiting to invade your lawn, and to then develop Integrated Weed Management and Integrated Pest and Disease Management programs to meet your specific needs.
We recommend using chemicals in dire circumstances to take back your lawn from weeds, grubs, and fungal diseases, before reverting back to organic practices and using good cultivation techniques to prevent and otherwise minimise the incidence of nasties in the lawn.
Sometimes it takes chemicals to rescue a lawn from a nasty infestation.
A lawn with good organic matter content in the soil can be less prone to grub damage, as these grubs will often feed on organic matter and turn to feeding on roots when organic matter is low. Likewise, an overall bird friendly garden will help prevent beetle numbers from growing too high and reduce the amount of beetle grub-eggs that get laid in the lawn in the first place. It is also possible to introduce beneficial nematodes to a grub infested lawn to target the grubs as an organic alternative to insecticides such as imidacloprid, which is known to be quite toxic and environmentally unfriendly. Lawns can also be irrigated just before dawn to bring grubs to the surface to be pecked at by birds, which can make a mess of your lawn but typically are a welcome warning sign of a more dire grub problems eating your lawns roots otherwise undetected.
Fungal outbreaks can be prevented by watering in the early morning to allow the midday sun to evaporate any excess water that doesn't drain to the root zone, while watering your lawn deeper and less frequently will also help prevent the humid conditions that fungus love.
Weeds can largely be prevented with a thick and healthy sward of turf that prevents other plants from ever seeing the light of day, but regular mowing before weeds can go to seed will keep them from spreading, and broadleaf dicotyledons will just not be able to stand up to the stress of mowing that the subapical meristemed grasses can endure. It is important to note that many weeds will adopt a prostrate habit and avoid being mowed, and therefore immediate hand weeding to prevent larger outbreaks, and good turf management to promote thick turf are both ess