Short answer: A coco brick is pressed, washed and buffered coco coir. Add water to expand it, check that the EC is low and the pH is near 6.0, then feed with a coco-specific main fertilizer from day one. Coco holds almost no nutrients of its own, so you control everything through the feed. Follow the feeding chart and adjust in small steps.
If you grow in coco, the coco brick is the easiest way to start. It is cheap to ship, easy to store and gives you fresh, light substrate in minutes. This guide shows you how to prepare a coco brick, why buffering matters, how to mix coco nutrients and how to use a coco feed chart for cannabis and other plants.
1. What is a coco brick?
A coco brick is coco coir (the fibre from the coconut husk) pressed into a dry block. It is light and compact, so it is easy to carry and store. When you add water, it expands to many times its size.
The Bionova Cocobrick 6x 10L is washed and buffered with calcium and magnesium. It is unfertilized (NPK 0-0-0) and has an EC below 0.5 mS/cm and a pH of 6.0. The pack holds six bricks, and each brick gives you 10 litres of ready-to-use substrate.
2. How to prepare a coco brick
Preparing a coco brick takes four simple steps.
- Place one brick in a clean bucket or tub.
- Add 4 to 5 litres of water per brick.
- Wait until the brick has fully expanded, then break up any lumps by hand.
- Fluff the coco so air can move through it before you fill your pots.
To speed this up, add Freeflow to the water. It is a natural wetting agent made from yucca extract, and it helps the water enter the dry fibre faster.
3. Why buffering matters in coco
Raw coco coir can hold on to calcium and magnesium and release other elements, such as potassium. This can leave your plants short of calcium and magnesium even when you feed correctly. Buffering means the coir is treated before it is pressed, so these places in the fibre are already filled.
A washed and buffered coco brick therefore starts you with a more stable root zone. If you use an unbuffered coco, you need to buffer it yourself before planting. With a buffered coco brick, you can skip that step.
4. How to mix coco nutrients
For coco, use a main fertilizer made for coco. Coco Forte A+B is a two-part main fertilizer (A 8-0-0, B 0-6-12) with a concentration of 1:600. You can use it from the first week of growth until one week before harvest.
Mix it in this order:
- Fill your vessel with water.
- Add Coco Forte A and stir.
- Add the same amount of Coco Forte B and stir again.
- Add stimulators or minerals after the main fertilizer, if your feeding chart says so.
- Measure EC and adjust the pH to 5.5–6.5.
Always add A and B to the water one at a time.
If you use Silution, add it to the water first, stir well and wait 30 minutes before you add the main fertilizers and stimulators.
5. Coco feed chart: how to use it
The Coco Forte label gives a continuous range of 9 to 18 ml per 10 litres of water, from the first day until one week before harvest. Where you sit in that range depends on the phase and on your plants. The exact dose per phase is in the official feeding chart, so always check it: see the Bionova feeding charts.
| Phase | What you feed | Dose and EC |
|---|---|---|
| Growth | Coco Forte A+B, plus stimulators from the chart | See the feeding chart |
| Start of flowering | Coco Forte A+B, plus flowering stimulators from the chart | See the feeding chart |
| Mid flowering | Coco Forte A+B, plus stimulators from the chart | See the feeding chart |
| Last flowering | Coco Forte A+B, as the chart shows | See the feeding chart |
| Rinse | Plain water, with the pH adjusted | Flushing is mandatory in the last week |
How to deviate from the chart
The chart is a starting point. Change the dose in steps of 10%, not more. Wait a few days and look at the new growth before you change again.
If you use soft or reverse osmosis water, the chart advises adding Ca 15 and MgO 10 to the mix. Check the amount in the feeding chart for your water. If your plants are long-flowering, extend the schedule from mid flowering.
6. Common mistakes with coco
Feeding too little water. Coco is not a soil. It has no stored nutrients, so every watering should contain nutrients.
Skipping the pH check. Coco works best at a pH of 5.5 to 6.5. Outside that range the plant takes up nutrients badly.
Reusing coco without care. If you re-use coco, make sure it is free of disease, pests or viruses first.
Changing too much at once. Small steps of 10% keep the root zone stable.
Which products to use
For a simple coco setup you need a coco brick, a coco main fertilizer and a way to measure EC and pH. Browse the full coco collection to see all products for this substrate. If you grow autoflowers in coco, read our autoflower nutrients feeding guide next.
FAQ
How do I mix coco nutrients?
Fill the vessel with water, add Coco Forte A, then the same amount of Coco Forte B, stirring after each. Then measure EC and set the pH between 5.5 and 6.5.
What is a coco feed chart?
It is a schedule that shows what to feed in each phase of the grow, from growth to rinse. You can find the Bionova coco feeding chart on the Bionova Nutrients website.
Which fertilizer should I use for coco cultivation?
Use a main fertilizer made for coco, such as Coco Forte A+B. It is made for coco substrate and for irrigation systems.
Do I need to buffer a coco brick?
Not if it is already washed and buffered, like the Bionova Cocobrick. Unbuffered coco needs to be buffered before you plant.
