GT Coco Feeding Guide: Grow & Bloom Chart, pH, EC and Tank Calculator
GT Coco is a two-part nutrient range designed for plants growing in coco fibre. Grow A+B supports vegetative growth, while Bloom A+B is used when plants move into flowering and fruiting. This guide brings together the classic GT Coco feed chart, the manufacturer’s current product directions and a practical mixing routine for Australian home growers.
Quick answer: Aim for a finished nutrient pH around 6.0. The classic GT Coco guide specifies 5.8–6.5, while Growth Technology’s current product instructions specify 5.5–6.5. Use the range printed on your own product label where it differs, and check both pH and EC rather than assuming a fixed dose will suit every crop.
How to mix GT Coco nutrients in the right order
- Fill a clean mixing tank with the measured volume of water. Note your starting EC.
- If using GT Silica, add it to the plain water first, stir thoroughly and allow it to disperse. Do not combine concentrates directly.
- Add the required quantity of GT Coco Grow A or GT Coco Bloom A. Stir well.
- Add the same volume of the matching Part B. Stir again. Never mix concentrated A and B together.
- Add any other chosen additives individually, stirring between additions and following each product’s label.
- Measure the final EC. If it is above your crop’s target, dilute with water; if it is below target, adjust the complete A+B feed carefully while keeping A and B equal.
- Check and adjust pH last, after the solution is thoroughly mixed. A target near pH 6.0 is a useful starting point.
GT Silica is alkaline and can raise pH, so adjusting pH before adding it creates unnecessary work. Wear suitable eye and hand protection when handling concentrated nutrients and pH adjusters.
GT Coco feeding chart by growth stage
The chart below is an indicative starting schedule adapted into a simpler layout from Growth Technology’s published GT Coco Growers Guide. All A+B values are millilitres of Part A and the same millilitres of Part B, per litre of water — not the combined total. GT Super PK and GT Silica are separate additives. EC values are guides, based on reverse-osmosis water, and should be adjusted to crop and water conditions.
On mobile, swipe the chart left or right to see every nutrient amount.
| Stage | Grow A + B (each mL/L) | Bloom A + B (each mL/L) | GT Silica (mL/L) | Super PK (mL/L) | EC guide (mS/cm) |
|---|---|---|---|---|---|
| Cuttings | — | — | 2 | — | 1.1* |
| Vegetative week 1 | 3.0 | — | 5 | — | 1.4 |
| Vegetative week 2 | 3.5 | — | 5 | — | 1.6 |
| Vegetative week 3 | 4.0 | — | 5 | — | 1.9 |
| Vegetative week 4 | 4.0 | — | 5 | — | 1.9 |
| Flowering week 1 | — | 3.5 | 5 | — | 1.9 |
| Flowering week 2 | — | 4.0 | 5 | — | 2.2 |
| Flowering week 3 | — | 4.0 | 5 | 1.0 | 2.3 |
| Flowering week 4 | — | 4.0 | 5 | 2.0 | 2.4 |
| Flowering week 5 | — | 4.0 | 5 | 2.0 | 2.4 |
| Flowering week 6 | — | 4.0 | 5 | 1.0 | 2.3 |
| Flowering week 7 | — | 4.0 | 5 | — | 2.2 |
| Flowering week 8 | — | 3.5 | 5 | — | 1.9 |
*The cuttings stage in the original chart uses Clonex Clone Solution (CCS) at 10 mL/L, rather than GT Coco Grow or Bloom. The classic chart is a reference, not a universal prescription. Current GT Coco Grow instructions indicate 3–4 mL/L of each part; current GT Coco Bloom instructions indicate 4 mL/L of each part, adjusted to the desired EC.
GT Coco tank calculator — calculate A, B and additives in millilitres
Enter the number of litres in your mixing tank and choose a stage. The calculator multiplies each product’s rate by your tank volume. It shows Part A and Part B separately to prevent double-dosing. These are starting amounts only; measure your final EC and pH before feeding.
Example: for a 20 L tank at vegetative week 1, use 60 mL Grow A, 60 mL Grow B and 100 mL GT Silica, then measure EC and adjust pH.
If the interactive calculator is unavailable, multiply each mL/L rate in the chart above by your tank volume in litres. Example: 3 mL/L × 20 L = 60 mL of Part A and 60 mL of Part B.
Want a printable chart for your own tank size? Use the Hunter Hydro personalised GT Coco feed chart to enter your litres, calculate every stage, and print or save the result as a PDF.
What pH should GT Coco be?
For the classic GT Coco programme, work within pH 5.8–6.5 and aim near 6.0 when mixing a fresh tank. The manufacturer’s current Grow and Bloom pages give a broader 5.5–6.5 range. A stable, correctly measured solution matters more than chasing a decimal place. Use clean pH calibration buffers and check the meter against known standards before trusting a surprising reading.
EC is equally important: it reflects the total dissolved mineral concentration, not the balance of individual nutrients. Source water, additives, plant variety and growth conditions all affect the final reading. Start conservatively with young or stressed plants and adjust gradually.
Growing in coco with fabric pots and saucers
For a simple home setup, fabric pots placed on suitable saucers or trays make it easier to manage watering and keep the area tidy. Choose a high-quality, properly buffered coco medium, water evenly and keep the root zone moist without leaving pots sitting in stagnant water. Check the medium’s moisture, the plant’s condition and the nutrient strength before changing your routine.
Coco holds more water than many growers expect. Poorly buffered coco, hard water or excessive feeding can cause nutrient imbalance. If plants slow down or leaf tips burn, check your EC, pH, irrigation frequency and root health before adding more products.
Shop GT Coco nutrients at Hunter Hydro
For the vegetative stage, see GT Coco Grow A&B 1 L or GT Coco Grow A&B 5.5 L. For flowering, see GT Coco Bloom A&B 5.5 L or GT Coco Bloom A&B 20 L. Product sizes and availability can change; use the live product pages for current details.
New to two-part feeds? Read our guide to choosing hydroponic nutrients and pH meter calibration guide.
Download the official GT Coco printable feeding guide
Download Growth Technology’s GT Coco Growers Guide (PDF). This is the manufacturer’s classic printable chart; it should be read alongside the current product label and the latest Grow and Bloom instructions.
GT Coco frequently asked questions
Do I add Part A and Part B together?
No. Add Part A to the water and stir, then add the same volume of Part B and stir again. Mixing concentrates directly can cause precipitation and make nutrients unavailable.
How much GT Coco Grow do I add to 20 litres?
At 3 mL/L, add 60 mL of Grow A and 60 mL of Grow B to 20 L of water. At 4 mL/L, add 80 mL of each part. Confirm the final EC for your crop.
Do I adjust pH before or after nutrients?
After. Add silica first if using it, then A, B and other additives, check EC, and adjust pH last.
Can I follow the feed chart without an EC meter?
You can use label rates as an initial reference, but an EC meter is strongly recommended. The chart assumes particular water conditions and may not suit your crop unchanged.