Redox Sulphate of Ammonia Fertiliser – Nitrogen Boost

Redox Sulphate of Ammonia 25kg: Fast-Acting Nitrogen and Sulphur Fertiliser for Lawns and Gardens

Redox Sulphate of Ammonia is a high-nitrogen fertiliser that gives lawns, vegetables and garden plants a fast, effective boost of leafy green growth. Also known as ammonium sulphate, it supplies around 20.5% nitrogen in a fast-acting form the plant can take up quickly, along with roughly 24% sulphur. That nitrogen and sulphur combination is what drives strong, lush foliage and rich green colour, which is why it is a long-standing favourite for greening up tired lawns and pushing leafy crops.

The nitrogen is the headline, but the sulphur matters too. Sulphur helps plants build the proteins and chlorophyll they need for healthy growth and good colour, and both nutrients work together to correct the pale, yellowing leaves (chlorosis) that signal a nitrogen or sulphur shortage. Applied during active growth, it acts quickly, so you tend to see results in leaf colour and vigour within a couple of weeks.

Sulphate of ammonia has a second useful property that sets it apart from other nitrogen feeds: it gradually lowers soil pH, making the soil more acidic. That makes it a smart choice for alkaline soils and for acid-loving plants such as azaleas, camellias, gardenias and blueberries. It is worth knowing this works both ways, so it is not the right pick where you need to keep soil neutral or alkaline. The granular formulation is easy to spread by hand or spreader, and it comes in 1kg, 2kg, 4kg and 25kg sizes, with the 25kg bag suiting larger lawns, veggie patches and regular feeders.

Key Features & Benefits

• High-nitrogen fertiliser (around 20.5% N) for fast, lush, leafy green growth

• Also supplies around 24% sulphur to support healthy growth and rich colour

• Fast-acting, so results in leaf colour and vigour show quickly during active growth

• Greens up tired lawns and boosts leafy vegetables and foliage plants

• Corrects pale, yellowing leaves caused by nitrogen or sulphur shortage

• Gradually acidifies soil, ideal for alkaline soils and acid-loving plants

• Easy-to-apply granular form for hand or spreader application

• Available in 1kg, 2kg, 4kg and 25kg packs

How to Use

Always apply at the rate on the pack, as rates vary with the plant and situation. As a general guide for granular sulphate of ammonia in Australian gardens, around 45g per square metre (roughly one adult handful) suits lawns and general garden use, repeated every few weeks through the growing season. Spread it evenly over damp soil or lawn, rake or lightly work it into the surface, and then water in thoroughly so it starts working and doesn't sit on the surface.

The key to using it safely is to keep the granules off the plant itself. Sulphate of ammonia can scorch foliage, so avoid letting it lodge on stems and leaves, and don't apply it to a wet lawn in hot weather. Watering in well after application washes any stray granules off the foliage and moves the nutrients into the root zone.

Getting the Best From It

• Water in every time. This is the single most important step. It activates the fertiliser and prevents leaf and lawn scorch from concentrated granules.

• Feed during active growth. Nitrogen feeds leafy growth, so apply through the growing season when plants are actively growing, not when they are dormant.

• Use it for acid-loving plants. Azaleas, camellias, gardenias and blueberries benefit from both the nitrogen and the gentle soil acidifying effect.

• Don't overdo it. More is not better. Too much nitrogen can burn plants and push soft, weak growth, so stick to the recommended rate rather than guessing.

• Mind the pH. Because it acidifies soil over repeated use, keep an eye on soil pH if you use it regularly, especially on soil that is already acidic.

Frequently Asked Questions

What is sulphate of ammonia used for?
It is a fast-acting nitrogen and sulphur fertiliser used to green up lawns, boost leafy vegetables and foliage plants, and correct nitrogen or sulphur deficiency. It also acidifies soil, which suits alkaline soils and acid-loving plants.

What is the nitrogen content?
It supplies around 20.5% nitrogen in the fast-acting ammonium form, plus roughly 24% sulphur. On an NPK basis that is about 21-0-0 with added sulphur.

Does sulphate of ammonia lower soil pH?
Yes. Over repeated use it gradually makes soil more acidic, which is helpful for alkaline soils and acid-loving plants like azaleas and blueberries, but something to watch if your soil is already acidic.

How do I apply it without burning my plants?
Spread it evenly, keep the granules off stems and leaves, and always water in well afterwards. Avoid applying to wet foliage in hot weather, and don't exceed the recommended rate.

When should I apply it?
Apply during the active growing season when plants are growing, repeating every few weeks as needed. Avoid feeding dormant plants, since the nitrogen is aimed at driving active leafy growth.

Where can I buy Redox sulphate of ammonia in Australia?
It is available online in 1kg, 2kg, 4kg and 25kg sizes, with delivery across Australia and local pickup in Bonnyrigg, NSW. Current pricing for each size is shown on this page.