So good for tomato’s
Ive been using on my tomato plants since seedling and now that its time for harvest its been since good growth the plant.
Amazing results from this fertilizer 10/10
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NPK 4-18-38 + Ca + Mg
Hydro & soil
Advanced Formula for
Flowering & FruitingNPK 4-18-38 + Calcium & Magnesium
A complete 3-part nutrient system for bigger blooms, heavier fruit set and stronger colour, from first flower to harvest.
- High-phosphorus NPK 4-18-38 for stronger blooms and heavier fruit set
- With calcium and magnesium for firmer, tastier, more colourful fruit
- Balanced for hydroponics and soil with steady feeding through every stage
- Boosts yield, flavour and bloom density across fruiting plants
$39.80
$48.00
Save 17%
$39.80/kg
In every kit
NPK 4-18-38
Bloom & fruit set
Calcium nitrate
Firmer fruit, cell walls
Magnesium sulphate
Greener leaves, colour
Choose select amount
“Ive been using on my tomato plants since seedling and now that its time for harvest its been since good growth the plant. Amazing results from this fertilizer 10/10”
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Description
A complete three-part feeding system for the stage when plants stop growing leaves and start making flowers and fruit. The high-phosphorus, high-potassium base drives bud set and fruit fill, while separate calcium and magnesium support firmer, better-coloured fruit.
When to use it
Feed with All Purpose 20-20-20 while plants are growing leaves and stems. Switch to Advanced Formula once plants begin budding, and keep using it through flowering and fruiting until harvest.
What each part does
NPK 4-18-38: low nitrogen keeps plants from putting energy into leaves, while high phosphorus and potassium support flowering, fruit set and fruit size.
Calcium nitrate: calcium builds strong cell walls for firmer fruit, while the nitrate form is readily available to plants.
Magnesium sulphate: magnesium sits at the centre of chlorophyll, helping keep leaves green and productive while plants carry fruit.
Why it comes in three parts
Calcium reacts with phosphate and sulphate when they are mixed together in concentrated form, which can lock nutrients up before they reach the plant. Keeping the parts separate means each one stays stable and available until you mix the feed with water.
Why growers choose it
More flowers, stronger fruiting: elevated phosphorus and potassium support flowering, fruit set and crop development.
Better fruit quality: potassium supports fruit filling, colour, flavour development and overall crop quality.
Added calcium for developing fruit: supports strong cell structure and helps reduce the risk of calcium-related deficiencies.
Added magnesium for healthy green growth: supports chlorophyll production for richer green leaves and helps prevent magnesium deficiency.
Everything for flowering and fruiting in one kit: the base nutrients plus separate calcium and magnesium are supplied together.
Kept separate for a reason: the three-part format maintains nutrient stability before mixing.
Soil or hydro: suitable for garden beds, pots, coco and hydroponic systems.
Soil, pots and hydroponics
Suitable for garden beds, containers, coco and hydroponic systems. Made from natural mineral raw materials.
ā Australian owned & manufactured
ā Natural mineral raw materials
ā Natural mineral raw materials
Guaranteed Analysis
NPK 4-18-38 base nutrition with separate Calcium Nitrate and Magnesium Sulphate. Made from natural mineral raw materials.
NPK 4-18-38 base
Separate mineral components
Supplied separately to complete the three-part feeding system.
Calcium Nitrate
Supplied and applied separately.
Supplied and applied separately.
Magnesium Sulphate
Supplied and applied separately.
Supplied and applied separately.
Trace elements
Guaranteed analysis of the NPK 4-18-38 base powder.
How to mix & feed
Three separate nutrients for strong growth, heavy flowering and bigger fruit. Mix and apply each nutrient separately.
ā Suitable for hydroponic and soil-based growing.
1
When to apply
When to apply
Budding: start when the first flower buds appear.
Active bloom: keep feeding throughout flowering.
Fruit set: use as flowers begin turning into fruit.
Fruit development: continue feeding while fruit fills out and sizes up.
2
Measure the rate Ā· per 10 litres of water
Measure the rate Ā· per 10 litres of water
Measuring scoop: one scoop holds about 6g.
3
Mix and apply one at a time
Mix and apply one at a time
1. NPK 4-18-38: dissolve in 10 litres of water, stir well and apply around the root zone.
2. Calcium Nitrate: dissolve in 10 litres of water in a clean container, then apply.
3. Magnesium Sulphate: dissolve in 10 litres of water in a clean container, then apply.
Important: never mix the three together
Do not combine the dry powders or their concentrated solutions. Always dissolve and apply each nutrient separately.
Do not combine the dry powders or their concentrated solutions. Always dissolve and apply each nutrient separately.
Using the hose-end sprayer
Make each bottle up to 1 litre and spray around the root zone, one nutrient at a time. Set the dial to A.
CompleteGrow fertiliser sprayerRinse the bottle and sprayer thoroughly between each nutrient.
Store each bag separately in a cool, dry place. Reseal after use and keep away from children and pets.
FAQ
When should I start using it?
Start using Advanced Formula once plants begin budding and continue through flowering and fruit development. Use All Purpose 20-20-20 during the earlier leafy growth stage.
How much do I use?
- Seedlings: 6g NPK 4-18-38 + 6g Calcium Nitrate + 3g Magnesium Sulphate per 10L of water.
- Growing, flowering & fruiting plants: 8g NPK 4-18-38 + 8g Calcium Nitrate + 4g Magnesium Sulphate per 10L of water.
Why does it come in three parts?
Calcium can react with phosphate and sulphate when stored together at high concentration. Keeping the nutrients separate helps prevent precipitation and keeps them available to the plant.
Can I mix all three parts together?
No. Do not mix the concentrated nutrients directly together.
- Dissolve and apply the NPK separately.
- Dissolve and apply the Calcium Nitrate separately.
- Dissolve and apply the Magnesium Sulphate separately.
How do I make the sprayer concentrates?
- NPK 4-18-38: 200g fertiliser + 800mL water.
- Calcium Nitrate: 100g calcium nitrate + 900mL water.
- Magnesium Sulphate: 50g magnesium sulphate + 950mL water.
Prepare and apply each solution separately.
What order should I apply them?
- Apply NPK 4-18-38.
- Flush the sprayer with clean water.
- Apply Calcium Nitrate.
- Flush again.
- Apply Magnesium Sulphate.
Does it work in hydroponics?
Yes. Advanced Formula can be used in hydroponic systems as well as coco, pots and garden growing systems. Keep the three nutrient components separate until diluted and applied.
How should I store it?
Store each component separately in a cool, dry place. Reseal the bags after use and keep them away from moisture, children and pets.
Reviews
5.0
Based on 13 reviews
Growing something great?
Share a quick review and a photo of your garden ā it really helps other gardeners.
100% rated it 4 stars or higher
Genuine reviews from CompleteGrow customers.
Customer photos
7
Worked really well for my flowers
I like growing alot of flowers and roses, i saw that this was the fertiliser for them and it sure was!
Highly recommend this fertiliser! Going to be going alot more flowers :)
Beautiful flowering
Fast shipping, and has finally made my tree produce some beautiful flowers!
Showing 3 of 13
Best For These Plantsā
Perfect for Fruiting Vegetables & Herbs
NPK Fertilizer for Root-to-Bloom Growth
How it Works
Mix all 3 parts
Feed Your Plants
Watch Them Thrive
Flowering & Fruiting Formula
High-Performance Feeding For Bigger Blooms & Better Fruiting
Direct your plant's energy exactly where it counts. This high-potassium ratio shifts plants out of leafy growth and into production, driving flower density, fruit weight and final harvest quality.
Tomato Plants
Heavier trusses, stronger fruit set, better flavour.
Takes over once plants move past early leafy growth and start pushing flowers, trusses and fruit.
- Roma
- Cherry
- Beefsteak
- Truss
See more tomato types
Fruiting Crops
Supports fruit fill, crop load and productive flowering.
Built for crops that need more than leafy growth support once they start putting energy into fruit.
- Capsicum
- Chilli
- Pumpkin
- Cucumber
- Eggplant
See more fruiting crops
Flowering Plants
More flowers, stronger colour, a longer bloom cycle.
For plants where bloom development matters more than soft leafy growth, through the full flowering season.
- Petunias
- Geraniums
- Hibiscus
- Bougainvillea
See more flowering plants
Berries & Vines
Great for fruiting vines and berry-producing plants.
A bloom-and-fruit focused feed for berry crops and climbing fruit through active reproductive growth.
- Strawberries
- Blueberries
- Zucchini
- Melons
See more berries & vines
Roses & Ornamentals
Bigger blooms and richer colour on established shrubs.
Feeds through bud formation and repeat flushes, so plants keep flowering instead of running to leaf.
- Roses
- Camellias
- Gardenias
- Azaleas
See more ornamentals
Hydro & Intensive Grows
Suited to controlled, high-performance growing systems.
For growers running intensive schedules where flowering and fruiting performance is the main focus.
- Greenhouse
- Hydro Crops
- Protected Growing
- High Yield
See more growing systems
Master-Grade Plant Performance
Mix
NPK 4-18-38: 6g / 10L
Calcium Nitrate: 6g / 10L
Magnesium Sulphate: 3g / 10L
Seedling recipe Ā· Dissolve separately Ā· Scoop = 6g
Apply
Water In ā¢ Or Use Our Sprayer
Ditch the measuring cups. Our precision sprayer automatically mixes the perfect ratio for you. Just attach to your hose, dial in your feed, and cover your entire garden in minutes with zero guesswork.
| Feeding Level | Mix (1L Bottle) |
|---|---|
| NPK Bag Only | 200g fertiliser + 800ml water |
Want faster, simpler feeding?
Thrive
EXPLOSIVE BLOOMS ā¢ SUPERIOR QUALITY
Engineered to maximize floral density, fruit sugars, and structural plant strength.
How Much to Mix
NPK 4-18-38 Mixing Calculator
Choose a recipe (per 10 L), enter litres ā weāll calculate grams for each component.
Dissolve each component separately. Scoop = 6 g.
Reviews From Our Gardener's
5.0
Based on 13 reviews
Growing something great?
Share a quick review and a photo of your garden ā it really helps other gardeners.
100% rated it 4 stars or higher
Genuine reviews from CompleteGrow customers.
Customer photos
7
So good for tomato’s
Ive been using on my tomato plants since seedling and now that its time for harvest its been since good growth the plant.
Amazing results from this fertilizer 10/10
Worked really well for my flowers
I like growing alot of flowers and roses, i saw that this was the fertiliser for them and it sure was!
Highly recommend this fertiliser! Going to be going alot more flowers :)
Beautiful flowering
Fast shipping, and has finally made my tree produce some beautiful flowers!
Showing 3 of 13
Great price very happy with this product. Basil, lettuce, chinese greens, chillies and other herbs. They all look healthy and have their first set of true leaves. Happy with the purchase
Lucas M
Verified Buyer
Delivered so quickly very impressive and Iām using this for hydroponic tomatoes and chilies which look sensational are flowering and fruiting already Iāll buy moreš
Sarah L
Verified Buyer
Fruiting & Flowering Plant Fertiliser ā High Phosphorus + Potassium
A premium high-phosphorus fertiliser engineered to drive exceptional flowering and fruiting performance. This fertiliser high in phosphorus and potassium delivers targeted nutrition for abundant blooms, larger fruits, and stronger flavour. Formulated with NPK 4-18-38, Calcium Nitrate, and Magnesium Sulphate, it acts as a complete bloom booster for vegetables, ornamentals, and fruit trees ā including citrus, tomatoes, berries, and peppers.
ā
High-phosphorus NPK 4-18-38 for prolific flowering and heavy fruit production.
ā High-potassium ratio strengthens fruit size, colour, and taste quality.
ā Includes Calcium & Magnesium for firm fruit, nutrient transport, and plant strength.
ā Ideal NPK fertiliser for fruit trees & citrus ā hydroponic or soil applications.
š¦šŗ Australian-made trusted by growers for consistent, high-yield results.
ā High-potassium ratio strengthens fruit size, colour, and taste quality.
ā Includes Calcium & Magnesium for firm fruit, nutrient transport, and plant strength.
ā Ideal NPK fertiliser for fruit trees & citrus ā hydroponic or soil applications.
š¦šŗ Australian-made trusted by growers for consistent, high-yield results.
NPK Ratio
- N 4
- P 18
- K 38
What NPK 4-18-38 Means
Higher P and K to drive budding, flowering and fruit quality while keeping foliage compact.
- Fruiting & flowering: Tomatoes, peppers, berries, cucurbits, roses, citrus.
- Compact growth: Low N helps prevent stretch; pushes blooms & fruit load.
- Already with Cal-Mag: Calcium (19%) strengthens cell walls; Magnesium (9.6%) powers photosynthesis and nutrient movement.
Read More
The 4-18-38 profile prioritises phosphorus and potassium. Phosphorus supports stronger roots and abundant flower initiation, while potassium drives colour, flavour and overall resilience. The modest nitrogen helps prevent stretch, directing energy into blossoms and fruit load. With added Calcium Nitrate and Magnesium Sulphate, plants also receive structural strength, resistance to tip burn, and improved chlorophyll activity.
- Seedling mix and Grow & Bloom recipes included for every stage.
- Gentle on roots; ideal for frequent feeding schedules.
- Works with soil, hydroponics and foliar applications.
FAQ
You get three essential components that deliver complete nutrition for flowering and fruiting plants:
āļø NPK 4-18-38 ā High phosphorus and potassium for strong flowering, fruit set, and colour.
āļø Calcium Nitrate ā Builds firm fruit, prevents blossom end rot, and supports growth.
āļø Magnesium Sulphate ā Boosts chlorophyll, nutrient uptake, and overall plant health.
Fertilisers with a higher K value in the NPK ratio are considered high in potassium. Examples include NPK 4-18-38, 13-13-36, or 0-0-50, which deliver concentrated potassium to enhance fruiting, colour, and flavour.
At CompleteGrow, our NPK 4-18-38 + Calcium & Magnesium is a professional-grade high-potassium fertiliser designed for fruiting and flowering plants. It improves sweetness, firmness, and resilience across a wide range of crops ā including tomatoes, peppers, citrus, and berries.
Which fertiliser is high in both phosphorus and potassium?
High-phosphorus and high-potassium fertilisers like NPK 4-18-38 combine the two most important bloom nutrients ā phosphorus (P) for root and flower formation, and potassium (K) for fruit size, quality, and colour.
This balanced blend provides full bloom support, making it ideal for plants that need energy for flowering and fruit set, such as tomatoes, strawberries, capsicums, and citrus trees.
What is the best high-potassium fertiliser in Australia?
For Australian growers, CompleteGrow NPK 4-18-38 + Calcium & Magnesium is one of the best high-potassium fertilisers available. Itās crafted for consistent results in hydroponic and soil-based systems, ensuring improved fruit yield, colour development, and disease resistance across all major crops.
High-phosphorus fertilisers have a larger middle number in their NPK ratio ā such as NPK 4-18-38, 10-52-10, or 10-30-20.
These blends encourage root growth, early flowering, and strong bud formation, making them ideal for fruiting and flowering plants.
For Australian growers, CompleteGrow NPK 4-18-38 + Calcium & Magnesium is a professional-grade fertiliser high in phosphorus and potassium, delivering powerful bloom and fruit performance.
Fruit trees require a fertiliser rich in phosphorus (P) and potassium (K) to support flowering, fruit set, and sweetness.
A formula such as NPK 4-18-38 provides the ideal nutrient balance for strong root systems and heavy fruit production, while helping prevent leaf drop and poor fruit colour.
When enhanced with Calcium & Magnesium, this blend offers professional-grade performance for citrus, mango, avocado, and stone-fruit trees ā suitable for both hydroponic and soil-based growing systems.
