Lawn feeds can be confusing, here we break down the basics
When shopping for lawn feeds, you will likely see 3 numbers such as 20-5-10 or 15-10-10 on the packet. These numbers refer to the percentages of Nitrogen (N), Phosphorus (P), and Potassium (K) contained in the product by weight. These are known as the the NPK and they are the main nutrients required for a healthy lawn health. Let’s break down what each one does and why balanced levels are important.
1. Nitrogen (N) – The Growth Booster
Nitrogen is the most crucial element for grass growth. It fuels lush, green color and promotes leaf development, making the lawn appear thicker and more vibrant. High-nitrogen feeds are great for spring, when grass needs a growth boost after winter dormancy. However, too much nitrogen can lead to overly fast growth, which requires frequent mowing and can make grass more susceptible to disease.
2. Phosphorus (P) – Root Strengthener
Phosphorus is vital for root development. It helps grass establish a strong root system, which is essential for nutrient absorption, drought resistance, and overall resilience. Phosphorus is particularly useful when establishing new lawns, as it promotes the deep roots that young plants need to thrive. However, phosphorus levels should be kept moderate for established lawns to prevent excess buildup in the soil.
3. Potassium (K) – Stress Resistor
Potassium improves the grass’s ability to withstand stress from drought, disease, and temperature extremes. It strengthens cell walls, helping grass maintain hydration during dry spells and reducing its susceptibility to lawn diseases. A healthy dose of potassium is often recommended before summer heat or in autumn, preparing the lawn to survive the harsher conditions of winter.
Choosing the Right NPK Balance
For different times of year, lawn feeds come with varying NPK ratios tailored to seasonal needs. High-nitrogen feeds are ideal for spring, while balanced or potassium-heavy feeds suit the end of summer or early autumn, ensuring the lawn remains robust and prepared for stress.
Here at Lawn-Kit.com we have partnered with the U.K.s best feeds manufacturer to leverage their extensive knowledge and experience to bring to the lawn enthusiast professional grade lawn feeds perfectly aligned to what your lawn needs for each season. You don't need to know the optimum NPK for each season, just apply the correct seasonal feeds and await great results.
Couple of final points...
Particle size - for granular feeds the smaller the particles the better, having more smaller particles means the nutrients are more evenly spread resulting in uniform growth and colour.
Controlled release feeds - some feeds are coated which delays the release of the nutrients. This enables the manufacturer to tailor the release profile to be evenly distributed over a period of time, or give a rapid initial nutrient release and then sustain feeding for a period of time (Spring Rise does this). A controlled release feed with 10% Nitrogen spread over 3 months delivers the same amount of Nitrogen as a 5% instant release feed (normally consumed by the lawn within 4-6 weeks), but the numbers on packaging are different so always check if the feed is controlled release or not.
Value- bearing the above in mind, if a feed lasts for 3 months you only need one application for a season whereas if the feed is instant release it will last around half this duration so you would need two applications for the season usually making these feeds more expensive options.. So you need to look at both the amount of nutrients and the period they are released over and the cost to determine a good value feed.