Solid fertiliser v Liquid fertiliser

With Spring weather finally upon us, it will soon be time to fertilise your lawn. Sometimes we get asked whether liquid fertilisers are better than solid fertilisers. It’s an interesting question!

My initial answer to this is both solid and liquid fertilisers contain nutrient which when applied to your lawn will fertilise it accordingly. That's about where the similarities end. Which type of delivery you use will largely depend on the purpose of your lawn and the results you're trying to achieve. Let me explain. 

Solid fertilisers:

These are the types of fertilisers you buy in bags and spread with a spreader or by hand. They have a granular consistency and need to be watered in immediately after application to prevent them from burning your lawn. In watering them in, you also carry out the essential function of transporting the nutrient down to the root zone where it is taken up by the lawn. Solid fertilisers typically have a high amount of nutrients contained in them and in most instances have a balanced ratio of essential elements like nitrogen, potassium and phosphorous. Some have extra goodies like iron and trace elements. They can have a combination of slow-release and fast release components but typically release a significant amount of nutrients, quickly, on application which is why you'll see your lawn turn green and grow faster within a week of application. These are the sort of results most home gardeners expect when fertilising and see it as a sign that their efforts to fertilise were worth it. 

Three to four weeks after application, the greening effect may start to fade and the initial growth surge will also begin to tail off. This will be a gradual effect as the nutrient in the soil becomes depleted, either by being used by the lawn or by being leached out by water. At about the 10-12 week mark, it will be time to fertilise again.  

​Liquid Fertilisers:

As the name suggests, these fertilisers are sprayed onto your lawn.  You buy them as a concentrate, mix them with water and apply them using a pressure sprayer or a watering can. Liquid fertilisers are not watered in like solid fertilisers as they are absorbed through the blades of the lawn rather than through the root zone. This method of fertilising is fast-acting and almost immediately available to the lawn. Like solid fertilisers, their liquid counterparts can have a range of nutrients in them but they are also available in individual elements and trace elements making this type of fertilising extremely versatile and customisable. The general concept with liquid fertilising is that you apply low amounts of nutrients, often with a typical application rate being once per fortnight. The low doses mean that there is very little chance of fertiliser burn however you won't get a big greening effect either but then, that's not the idea with this type of fertilising. It's more about maintaining a close to constant level of nutrition in your lawn without the highs and lows of a solid fertiliser regime. 

The following chart illustrates how these two forms of fertiliser act on your lawn. The yellow line represents solid fertilising with the red dots on the line representing an application of fertiliser. You can see that when the fertiliser is applied, nutrient levels in the lawn rise dramatically resulting in dark green colour and fast growth. The nutrient levels slowly fall away over time resulting in the lawn gradually losing its colour. When they become too low, another dose is applied which repeats the same cycle. The blue line represents liquid fertilising, again with the red dots representing applications of fertiliser.  You can see that that the level of nutrients doesn't rise as much as it does with solid fertilising however you don't get the lows of solid fertilising either. One of the biggest advantages is that the nutrient levels stay fairly constant which is good for the lawn but does require a much higher frequency of application.

Which type should you use?

As I mentioned earlier, this depends on a lot of factors. If you're a home gardener that just wants a healthy, green lawn then fertilising with a solid fertiliser is the best choice for you. You only have to do it 3 times per year making it simple and effective without tipping too much time into your lawn. While they are not as versatile or as fast-acting as liquids, they are less complicated to apply and less time consuming to keep on top of.  They do a great job of delivering all of a lawns essential requirements.

If you're a turf professional such as a golf course manager or an oval curator, you might lean more on liquid fertilisers for their versatility, fast results and their ability to keep lawns healthy without surges in growth. They are even starting to pick up steam with home gardeners who want the perfect lawn and don't mind tipping more time and effort in to get the results. 

Whether you use liquids, solids or a combination of both, maintaining good lawn nutrition is an important step in keeping your lawn healthy, more disease and pest resistant and for keeping it looking good year-round.