Keeping plants green, healthy, and thriving often comes down to one key nutrient: Nitrogen. Many gardeners struggle with yellowing leaves, slow growth, or patchy lawns, and in most cases, it’s a lack of nitrogen in the soil that’s the culprit. But while nitrogen fertilisers are one of the most effective ways to restore plant health, knowing how, when, and where to use them is just as important as the fertiliser itself.
In this guide, we’ll answer all your questions about nitrogen fertilisers, from understanding what they are to knowing the signs of deficiency, overuse, and the right time to apply them.
A nitrogen fertiliser is any fertiliser product designed to supply plants with nitrogen (N), one of the most vital nutrients for growth. These fertilisers may come in organic forms, like blood meal or compost, or in synthetic forms, such as urea, ammonium nitrate, or NPK blends. They are especially useful for lawns, leafy vegetables, and crops that demand high levels of nitrogen.
Nitrogen is one of the three essential nutrients in fertilisers (alongside phosphorus and potassium). It plays a key role in photosynthesis, helping plants produce lush green leaves and strong stems. Fertilisers labelled with “NPK” always include nitrogen as the first number in the ratio.
Promotes vigorous leaf and stem growth
Enhances photosynthesis and plant energy
Improves overall plant health and colour
Supports crops, lawns, and leafy vegetables in producing higher yields
A simple soil test kit will show the nutrient levels in your soil. However, gardeners often notice visual cues first, like pale leaves, slow growth, or poor lawn recovery after mowing are all signs your soil might be lacking nitrogen.
Yellowing of older leaves (starting from the base)
Stunted growth or poor development
Reduced fruit or flower production
While nitrogen is essential, over-fertilising can cause problems:
Excessive leaf growth with fewer flowers or fruits
Weak stems prone to bending or breaking
Increased susceptibility to pests and diseases
Not all plants thrive on nitrogen. Root crops like carrots, beetroots, and radishes can suffer if nitrogen levels are too high, as the plant will focus on leaf growth instead of developing roots.
The best time depends on your plants.
Nitrogen is highly soluble and can leach away with watering or rain. On average, it remains effective in soil for 2–6 weeks, depending on whether the product is fast-release or slow-release.
Quick-release fertilisers such as urea or ammonium nitrate give immediate results. For a more natural option, blood meal or liquid seaweed solutions can also provide a rapid nitrogen boost.
Yes, coffee grounds contain small amounts of nitrogen and can improve soil structure. However, they work best as part of compost rather than as a standalone fertiliser.
Overuse can damage plants and soil health
Leaching may contribute to water pollution
Needs regular reapplication due to its mobility in soil
Selecting the right product depends on your goals. Lawns benefit from fast-release options for quick greening, while crops and garden beds often do better with balanced NPK or organic slow-release fertilisers.
At Garden Nursery Products, we stock a full range of nitrogen fertilisers designed for everything from lush lawns to thriving vegetable patches. Whether you need a quick nitrogen boost or a long-lasting soil solution, our team can help you choose the best product for your needs. If you’re on the Gold Coast, explore our full fertiliser range today by visiting our store or shopping online. Shop now.
