What Are Liquid Fertilisers? A Complete Guide for Australian Gardeners

Looking for the best liquid fertiliser for your garden or potted plants? Whether you’re feeding tomatoes in containers, flowers in raised beds, or herbs on your balcony, liquid fertilisers provide quick, targeted nutrition. In this guide, we’ll explain what liquid fertilisers are, why they’re effective, and how to use them for faster, healthier plant growth.

What Are Liquid Fertilisers?

Liquid fertilisers are concentrated nutrients dissolved in water, formulated for rapid plant uptake. Unlike granular fertilisers, which take time to break down in soil, liquid fertilisers deliver immediate nutrition to the roots or foliage. They contain essential macronutrients—Nitrogen (N), Phosphorus (P), and Potassium (K)—alongside vital micronutrients like magnesium, boron, iron, and calcium.

Why Use Liquid Fertiliser?

Not all fertilisers are created equal. Liquid fertilisers offer unique advantages, especially in modern and compact gardening setups:

✅ Fast-acting and easily absorbed: Perfect for correcting nutrient deficiencies or boosting stressed plants.

✅ Flexible application: Can be applied as a root drench or foliar spray.

✅ Even distribution: Ideal for containers, raised beds, and drip-fed systems.

This makes them a favourite for both home gardeners and commercial growers who need efficient, mess-free nutrition solutions.

Best NPK Ratios for Plant Stages

Liquid fertilisers come in different NPK ratios for different growth phases:

Seedlings: Use a gentle, balanced half mix of our All Purpose mix (e.g. 10-10-10) to avoid overloading young roots.

Leafy growth phase: Use high-nitrogen blends (e.g. 20-10-10) to promote vigorous foliage.

Flowering and fruiting: Choose high phosphorus and potassium (e.g. 10-20-20) for stronger blooms and yield.

Our top-selling NPK 20-20-20 liquid fertiliser is ideal for all-purpose feeding and includes chelated micronutrients for balanced plant health.

Common Liquid Fertiliser Mistakes to Avoid

Feeding your plants too much or at the wrong time can do more harm than good. Watch out for:

❌ Over-fertilising: Stick to recommended dilution rates to prevent salt buildup or leaf burn.

❌ Skipping pH checks: Aim for a soil pH of 6.0–7.0 so nutrients are readily available.

❌ Applying during midday heat: Early morning or late afternoon feeding reduces stress and maximizes uptake.

Why CompleteGrow Liquid Fertilisers Are Trusted

✅ 100% soluble and fast-acting: No residue, no blockages—just clean, effective nutrition.

✅ Balanced macro and micronutrients: Formulated for all-round plant development.

✅ Odour-free and safe for indoor use: Ideal for balcony gardens, greenhouses, and houseplants.

✅ Proven in Australian conditions: Loved by home growers and pros from Cairns to Perth.

Perfect for veggies, fruiting plants, ornamentals, and lawn maintenance.

Ready to Boost Your Garden with Liquid Fertiliser?

If you’re searching for an effective, easy-to-use liquid fertiliser in Australia, try our CompleteGrow NPK liquid range. It’s designed for quick absorption, great results, and hassle-free application.

Need personalised advice for your plant setup? Get in touch with our experts →

Comments (2)

Rolando Martin

August 24, 2025 - 9:33 am Reply

Hi there,

I’m in Southwest WA and first time of using this fertilizer on my potted avocado, my avocado produced flowers but not successfully making fruit, all the flowers fell off nothing left on the stem last season. I decided to try your 20-20-20 product and see how it goes. Do you have recommendations of how much solution to be feed to every tree every 7 to 14 days? I’d seen that the preparation will be 3tsp per 5Liters of water, is that 5L is for every tree? Your response is very much appreciated. Thank you.

Completegrow - Dan

August 24, 2025 - 11:39 am Reply

That 5L is your prepared solution, and is divided per tree depending on its size:

– Young/smaller potted trees: around 1–2L per feed –

– Medium trees: around 2–3L

– Larger potted trees: up to 5L if draining well.

Apply every 7-14 days during spring and summer for best results.

Flower drop: Avocados often drop flowers naturally when young. With fruit bearing once the tree is mature enough (usually after 3–5 years)

Rolando Martin

August 24, 2025 - 9:33 am Reply

Hi there,

I’m in Southwest WA and first time of using this fertilizer on my potted avocado, my avocado produced flowers but not successfully making fruit, all the flowers fell off nothing left on the stem last season. I decided to try your 20-20-20 product and see how it goes. Do you have recommendations of how much solution to be feed to every tree every 7 to 14 days? I’d seen that the preparation will be 3tsp per 5Liters of water, is that 5L is for every tree? Your response is very much appreciated. Thank you.
- Completegrow - Dan
  
  August 24, 2025 - 11:39 am Reply
  
  That 5L is your prepared solution, and is divided per tree depending on its size:
  
  – Young/smaller potted trees: around 1–2L per feed –
  
  – Medium trees: around 2–3L
  
  – Larger potted trees: up to 5L if draining well.
  
  Apply every 7-14 days during spring and summer for best results.
  
  Flower drop: Avocados often drop flowers naturally when young. With fruit bearing once the tree is mature enough (usually after 3–5 years)

Liquid Fertilisers for Gardens & Containers

What Are Liquid Fertilisers? A Complete Guide for Australian Gardeners