Selecting the right fertiliser for your lawn is about matching the product to the right season and then to your lawn’s specific needs.
Lawn fertiliser is analysed by macro and micronutrients, starting with the three significant macronutrients – Nitrogen (N), Phosphorous (P), and Potassium (K).
More specialised fertilisers can also include a blend of micronutrients which perform different functions. These might include Calcium (Ca), Iron (Fe), Magnesium (Mg), Zinc (Zn), and Sulphur (S), as well as seaweed and amino acids.
Think Season First
Nitrogen encourages lush green growth, so as a basic rule you will only need this nutrient in a higher ratio during the growing season – spring and summer.
During the cooler months of autumn and winter, you will want to reduce the amount of nitrogen in your fertiliser because it will encourage soft new growth which can be damaged by frost and attract fungal infections and other diseases.
So, in autumn and winter, turn your attention to the nutrients that build root strength and harden the grass without encouraging the grass to put on growth. Look for an analysis with a lower ratio of nitrogen, but higher potassium and phosphorous.
For a general maintenance feed, choose the following:
Typical spring / summer lawn fertiliser:
- Nutrigrow 9-7-7 Spring/Summer Blend. Note the higher balance of Nitrogen (9%), compared with 7% potassium and 7% phosphorous.
Typical autumn / winter lawn fertiliser:
- Nutrigrow 3-12-12 Autumn Blend. Note the lower balance of nitrogen (3%) to potassium and phosphorous (12%).
Once you’ve got to grips with this basic rule relating to nitrogen and the seasons, you can start to turn your attention to your lawn’s specific needs.
Assess Your Lawn
While a general feed is a good idea for all lawns twice a year (a spring and autumn feed), you may be facing additional challenges with your lawn and need a different blend of nutrients. This is where those micronutrients come into play
Here are some of the main reasons people look for a more specialised fertiliser and an example of the type of fertiliser you might choose to treat the problem:
Moss
Iron (Fe) blackens moss ready for you to remove it by scarifying. If your lawn contains a lot of moss, look for a fertiliser that contains iron, like Nutrigrow High Fe 4-0-4 + 9Fe. Note the relatively low percentage of nitrogen, meaning it is safe to use in the cooler winter months.
Yellowing Grass
A fertiliser with magnesium like Nutrigrow 18-3.5-8+1Mg Phased Release is formulated to help address chlorosis – the scientific term for the yellowing of grass blades. The added magnesium helps provide a deep natural green colour because the central atom in magnesium is chlorophyll - without which grass cannot photosynthesise. Note the high percentage of nitrogen (18%), so only use this fertiliser in spring or summer.
Excessive Weeds
Lawns that are struggling with weeds will be weak and need both nutrition and an herbicide to treat the weeds themselves. For problematic lawns like this, choose a multipurpose fertiliser with selective herbicide like Nutrigrow Feed, Weed and Moss Killer. This product has a nutrient analysis of 10-2-2 + 8% iron sulphate, together dicamba mecoprop-p as the selective active herbicide.
Waterlogging
When your grass is suffering from excessive rain and waterlogging, the primary issue is nutrient leaching – where nutrients are washed away before they can benefit the grass. To fix this, you will need to focus on root recovery. Choose a foliar fertiliser like Autumn-gem 4-2-16. A liquid fertiliser can help when the soil is very wet or saturated as the waterlogged roots are often ‘shut down’ due to a lack of oxygen, so spraying a liquid fertiliser like this can help give the grass an immediate boost of potassium to help it recover.
Drought
If your lawn is looking brown and dormant following drought or periods of intense heat, avoid using a heavy granular feed as it will be difficult to encourage absorption. Choose a liquid feed like Sward Booster G. This is a biostimulant rich in amino acids – the ready-made building blocks for recovery, helping the lawn green up much faster once the rains return. For very dry lawns, a wetting agent like Abzorb can also help with water penetration and retention.
Often lawns contain a mix of issues and can experience one or all of these challenges through the season. However, rather than applying lots of different treatments throughout the year, focus on a plan of two to four applications a year remembering that grass needs a nitrogen boost in spring, and strengthening (phosphorous and potassium) in winter.
Summary of Recommended Fertilisers
| Product Name | N-P-K Analysis | Primary Use / Benefit | Recommended Timing |
| Nutrigrow 9-7-7 Spring/Summer Blend | 9-7-7 | Encourages lush green growth. | Spring and summer. |
| Nutrigrow 3-12-12 Autumn Blend | 3-12-12 | Builds root strength and hardens the grass. | Autumn and winter. |
| Nutrigrow High Fe 4-0-4 + 9Fe | 4-0-4 + 9% Iron (Fe) | Blackens moss for removal via scarifying. | Cooler winter months. |
| Nutrigrow 18-3.5-8+1Mg Phased Release | 18-3.5-8 + 1% Magnesium (Mg) | Addresses chlorosis (yellowing) and provides a deep green colour. | Spring or summer only. |
| Nutrigrow Feed, Weed and Moss Killer | 10-2-2 + 8% Iron + Herbicide | Multi-purpose treatment for weak lawns with excessive weeds. | Growing season (indicated by 10% nitrogen). |
| Autumn-gem (Liquid/Foliar) | 4-2-16 | Aids root recovery during waterlogging or when soil is saturated. | Periods of excessive rain. |
| Sward Booster G (Liquid) | Biostimulant (Amino Acids) | Provides building blocks for fast recovery after drought or intense heat. | Following drought once rains return. |
For specific questions relating to your lawn’s needs, please get in touch with our technical team for free specialist advice.
This post was written in collaboration with Spencer Haines.
Spencer Haines
Spencer Haines is an experienced turf industry professional and Agrigem’s Technical Account Manager in charge of lawncare. Spencer manages Agrigem’s lawn customers as well as bowls clubs, schools and colleges, and is highly knowledgeable in the technical aspects of creating and maintaining high-performance turf.
Spencer’s experience in professional turf maintenance is coupled with a genuine interest and enjoyment of lawn care that he shares with customers; providing expert advice and guidance built on solid experience. He focuses on working closely with customers to deliver on specific objectives – on time, on budget and to exacting standards.
Article Notes:
Nutrigrow is a trademark of Agrigem Ltd.
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