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  • Liquid Iron Fertiliser - 4L
Liquid Iron Fertiliser - 4L

Liquid Iron Fertiliser - 4L

Supercharged with Fulvic Acid - 7% Iron ; 3% Sulphur

Liquid Iron Fertiliser - 4L
RRP $49.95
SAVE $9.99 (20%)
NOW $39.96
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Product Description

Kickstart Greener Growth, Fast

Struggling with yellowing leaves or dull, patchy grass? Plant Doctor Liquid Iron Fertiliser is a powerful iron-rich solution enhanced with Fulvic Acid for rapid uptake and visible results. It revives pale, iron-deficient plants by boosting chlorophyll production, helping lawns and gardens bounce back with deep, lush colour. Whether you're rescuing a tired lawn or restoring vigour to fruit trees and ornamentals, this easy-to-apply liquid gets nutrients where they’re needed, fast.

Greener overnight. Purchased A Small 1L bottle as a test for my footpath, sprayed it out and too my surprise the next morning it was noticeably greener. Took only 2 or so more day to get a lovely shade of green. 100% adding this to my arsenal for that lovely green during winter for my whole lawn.
— Kevin
Why choose Liquid Iron:
  • Corrects yellowing (chlorosis) from iron deficiency
  • Promotes rich, deep green colour in lawns and foliage
  • Supports strong, healthy plant growth
  • Fulvic acid speeds up nutrient absorption
  • Compatible with most humic and soil-based fertilisers*
  • Works via foliar spray or soil drench
  • Suitable for turf, trees, vines, flowers, veggies & ornamentals
Nutrient Profile:
Fe
Iron
7%
S
Sulphur
3%

Functional Additives

  • Fulvic acid (bio-chelating agent) – improves uptake efficiency and translocation
  • Liquid carrier designed for foliar + soil absorption

*Always do a quick “jar test” for compatibility before mixing. Compatible with most humic/fertiliser blends 

 

Where to use Liquid Iron 

Lawns
(Buffalo, Couch, Kikuyu & More)
  • Ideal for all turf types with iron deficiency or poor colour.
  • Use as a fast-acting foliar spray or soil application during growing season.
  • Apply in cooler conditions for best results, early morning or late afternoon.
Gardens
(Veggies, Flowers, Trees, Pots)
  • Fix yellowing in roses, camellias, hydrangeas, citrus, and more.
  • Spray on leaves or apply to soil around roots.
  • Use in garden beds, veggie patches, and flowering plants.
Farms & Acreage
(Broadacre, pastures, orchards, vineyards)
  • Great for vines, orchards, berries, tree crops, and pasture needing a colour boost or iron correction.
  • Helps address iron lockout from high pH or calcareous soils.

Use Liquid Iron when your lawn or plants show yellowing with green veins, have lost their green shine, aren’t responding to fertiliser, or need a fast colour boost, especially after heavy lime use or in alkaline soils.

 
The Science Behind Liquid Iron:

Iron is essential for chlorophyll formation — the green pigment that drives photosynthesis. But in many Australian soils, iron gets locked up due to high pH, compaction, or excessive lime.

This formulation contains:

  • 7% Iron (Fe): A highly available form plants can absorb quickly
  • 3% Sulphur (S): Helps acidify the soil slightly and aids iron uptake
  • Fulvic Acid: A natural organic acid that chelates nutrients and speeds up delivery through leaves and roots

The result? Fast correction of iron chlorosis (yellowing), deeper green foliage, and improved photosynthetic function for overall healthier growth.

Bring Back the Green, Fast. There’s no need to live with yellowing plants or dull, pale grass. Liquid Iron with Fulvic Acid delivers fast, visible results, greening up your landscape while giving plants the micronutrient support they need to thrive. Restore colour, strengthen growth, and keep your garden glowing, all in one simple, effective dose.

Safety Guidelines

Do not spray in hot weather conditions. Not compatible with many products. Check the labels and do a jar test first. Iron can stain paths, concrete, paving, clothes, and skin, so always wear old clothes, wash hands after use, and be careful when applying near concrete and paths, etc. Wash off immediately any lasting damage. Keep away from water sources such as ponds, pools, etc. Safe for children & pets when dry. Iron deficiency in many plants & lawns is an indication of high pH or alkaline soil. If yellowing persists or returns rapidly after treatment, soil pH should be checked and adjusted if necessary. Follow application directions as excess liquid iron can lead to other problems, such as zinc and manganese deficiencies. While liquid iron provides immediate relief for plants & soil, it is not an adequate long-term solution for an iron deficiency. Keeping plants/lawn in well-drained soil amended with sulphur to reduce the pH level can help iron in the soil become more available to plants.

(LIR04L)

Product Application

Important Note: Iron products can have an adverse reaction with our darker liquids. To avoid blockages in sprayer nozzles, we recommend applying the Iron separately from other products. (Stimulizer is safe to mix with Iron).

If attempting to mix together, try a jar test in the ratios you want to apply them in first. Iron should always be added last, after all other products are diluted with water.

Applied separately at various frequencies allows you to tailor nutrient input based on the soil/plant/lawn's requirements and condition.

Application Rate:

Minimum dilution rate: 1:50

Application Type Rate Frequency
Turf 150-400ml/100sqm
1.5-4L/Ha
Apply every 4 weeks in growing season or as required
Ornamental Plants 10-25ml/10litres water
100-250ml/100sqm
Apply every 4 weeks in growing season or as required
Vegetables 150-300ml/100sqm
1.5-3L/Ha
Apply fortnightly or as required
Trees, Fruits, Nuts & Grapevines 150-300ml/100sqm
1.5-3L/Ha
Apply every 6-8 weeks or as required
Broadacre Crops 3-8L/Ha Apply as required with normal program

 

 

Need Help with Application Rates?

Not sure how much to apply for your lawn or garden area? Use our Plant Doctor Product Rates Calculator to get the correct rate tailored to your size and conditions.

Open Application Rate Calculator

 

Popular Questions

Should I water the lawn after applying Liquid Iron or wait 24 hours?

Liquid Iron doesn’t have to be watered in, although some prefer to water it in. Either approach is acceptable. Environmental factors such as time of day, wind, rainfall, soil pH, and leaf contact duration can all affect how well Liquid Iron performs. For best results, apply in calm, dry conditions and avoid mowing immediately after application.

Can I mix Liquid Iron with other products?

Liquid Iron should not be mixed with other products, except for Stimulizer. Mixing it with fertilisers or foliar sprays may cause chemical reactions or reduce product effectiveness.

How often should I apply Liquid Iron to my lawn?

Application frequency can depend on your grass type, climate, and soil conditions. Many lawn lovers use it every 2–4 weeks during the growing season to maintain deep green colour and correct iron chlorosis. Always follow label guidelines and adjust based on lawn response.

What are the signs of iron deficiency in lawns and plants?

Look for yellowing leaves with green veins (a condition known as interveinal chlorosis), stunted growth, or a dull, pale lawn colour. These symptoms often indicate that your soil is lacking available iron, especially in alkaline soils or after heavy liming.

Can I use Liquid Iron on garden plants or just grass?

Yes, Liquid Iron is suitable for lawns, ornamentals, shrubs, and fruit trees. It helps correct iron deficiencies and enhances foliage colour across a range of plant types, not just turf.

Is Liquid Iron safe for pets and children?

When used as directed and allowed to dry before re-entry, Liquid Iron is safe for use around children and pets. It’s always a good idea to keep them off the treated area until the lawn is dry.

What’s the best time of day to apply Liquid Iron to my lawn?

Early morning or late afternoon is ideal to avoid leaf burn from midday sun and improve absorption. Avoid applying if rain is expected within a few hours.

Why is my lawn yellow even after fertilising?

If your lawn remains yellow despite regular fertilising, it may be suffering from iron deficiency, especially if the soil is alkaline or compacted. Liquid Iron provides a fast-acting source of iron that can restore colour within days.

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Amount of Reviews: 9

Awesome product

By: jade on 13 November 2024
My lawn has never looked better 12 months in after using 5 different products. Its looking mint !

Liquid iron

By: Bryce on 10 November 2024
Really happy with the results so far, lawn is looking very lush and green since applying! You won’t be disappointed!!

Great service and fast shipping.

By: jade on 12 March 2024
Liquid iron Fert is a fantastic product which exceeded my expectations. I’ll be back again!

LUSH AND GREEN

By: Tanya on 6 February 2024
Love this product, made my new lawn from light green to a bright vibrant green in only two applications! Highly recommend.

3rd order - Santa Ana Googong

By: Stuart on 8 January 2024
Hi team, thank you for the prompt delivery across the Dec-Jan period. I have been using your lawn products exclusively and really happy with the results on our lawn, albeit a bit wet here near Canberra in Jan! I ran out of the liquid iron, Quantum H and Seaweed Secrets earlier than the other products (higher rate of use), I will consider upping to the 10L next round. I will add some pics to your gallery when I can, but can thoroughly recommend this line of lawn care. I use a combination of Liquid Iron, Seaweed Secrets, Humic Acid, Stimuliser, Quantum H, Activ8 Mate (changing to Activ8Extra). All applied with a manual backpack sprayer, we have about 100sqm front and 100sqm rear lawn. Thank you and keep up the great work, cheers Stuart. PS: Feel free to add this review to Quantum H and Seaweed Secrets as they were purchased with this product.

Green Gold

By: David on 3 August 2023
What a difference this makes. Makes all the difference for plant health and colour.

Quick Green up

By: Anferny on 9 August 2021
Definitely another fantastic products from the plant doctor to get a quick green up on the lawn. Also adding to a little bit of iron and stim in my vegetable garden help the leaf much stronger green. Would recommended to have this product on their shelves

My favourite product!

By: Sheldon on 9 January 2021
I love using Plant Doctor's liquid iron. It always makes my lawn 'pop'. It is fast acting too.

So Green!

By: Brad on 8 May 2020
Applied Liquid Iron to my lawn and within two days it was noticeably greener, very happy with the product.
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Customer Reviews

5

First time owning lawn. Gave the team at plant doctor a ring and they supplied me with a wealth of information. Products turned up quickly.

Billy Green

5

Will definitely be getting more 8 weeks difference been using stimulizer, activ8mate, soil wetter, seaweed secrets and champion fertiliser. Was super fast delivery.

Michael Preddy

5

Only have great things to say about Plant Doctor. Organic products and a competitive price, fast shipping and easy to contact with questions. Have had great results with the special mix for lawns, and my plants (indoor and outdoor) love the seaweed secrets. I am excited to test out some of the animal products soon!

Tim McAuliffe

Plant Doctor

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