How Much Nutrient Should I Use?
Feeding your FlowGrow tower is simple once you know the basic rhythm. Use equal parts A and B, start gently while plants are young, and increase nutrient strength as your plants grow stronger.
Hydroponic nutrients do not need to feel complicated. With FlowGrow, all standard feeding guidance is based on a 15 litre working reservoir, which keeps measuring simple and consistent across FlowGrow towers.
The aim is not to chase perfect numbers. It is to give your plants a steady, balanced feed that supports healthy growth in real home conditions.
Use the same amount of Part A and Part B every time you feed your tower.
FlowGrow dosing is based on the recommended 15 L working reservoir fill.
The simple version: add nutrients to water, use equal parts A and B, and adjust strength gradually as your plants grow.
The basic FlowGrow feeding rule
FlowGrow nutrients come in two parts: Part A and Part B. These are designed to be used together in equal amounts.
This means if you use 40 ml of Part A, you also use 40 ml of Part B.
Important mixing note
Always add nutrients to water. Never mix concentrated Part A and Part B directly together before adding them to your reservoir.
How much water should I use?
All FlowGrow towers use a 20 L reservoir base, but the recommended working fill is 15 litres.
This gives enough water for the system to run well while making nutrient measurements easier and reducing the chance of overfilling.
Use this as your standard: fill your FlowGrow reservoir with 15 litres of water, then add the matching amount of Part A and Part B.
FlowGrow feeding guide for a 15 L reservoir
Start with the stage your plants are at. Young plants need a gentler mix, while plants with healthy roots and strong growth can usually handle a stronger feed.
| Plant stage | Part A | Part B | Approx. EC | Best used for |
|---|---|---|---|---|
| Seedlings | 15 ml | 15 ml | ~0.2 | Young seedlings, early roots, and gentle first feeding. |
| Leafy greens and herbs | 40 ml | 40 ml | ~0.5 | Lettuce, herbs, leafy greens, and everyday home growing. |
| Plants growing strongly | 80 ml | 80 ml | ~1.0 | Plants with healthy roots, steady new leaves, and stronger growth. |
These amounts are designed to be practical and easy to measure. EC readings can vary slightly depending on your water quality, temperature, and growing conditions.
When should I use Grow nutrients?
FlowGrow Grow nutrients are used for leafy and vegetative growth. This is the nutrient most home growers will use when starting with herbs, lettuce, leafy greens, and young plants.
Use Grow nutrients for:
- seedlings
- leafy greens
- herbs
- early plant growth
- plants focused on leaves, stems, and roots
If you are starting with lettuce, basil, parsley, coriander, spinach, bok choy, or similar leafy crops, Grow is usually the right place to begin.
When should I use Bloom nutrients?
FlowGrow Bloom nutrients are used when plants begin shifting into flowering and fruiting.
Use Bloom nutrients when plants begin:
- flowering
- forming buds
- setting fruit
- moving beyond leafy growth
Bloom can be useful for plants such as strawberries, compact tomatoes, and chillies once they begin moving into their flowering or fruiting stage.
Grow nutrients vs Bloom nutrients
Grow and Bloom are both used in equal parts A + B. The difference is what stage of growth they support.
Should seedlings start on full strength?
No. Seedlings usually do best with a gentle start.
Young plants are still developing roots and adjusting to the tower environment. Starting with a lighter nutrient mix helps reduce stress while roots settle in.
For seedlings: use 15 ml Part A + 15 ml Part B in a 15 L reservoir.
Once plants are growing steadily and roots are becoming more established, you can move to the leafy greens and herbs strength if suitable.
How often should I add nutrients?
Add nutrients when you first fill your reservoir, and again when you refresh the reservoir water.
If you are topping up with small amounts of water between refreshes, you may not need to add full-strength nutrients every time. This is because plants use water and nutrients at different rates.
For most home growers, the simplest routine is to keep water topped up, observe plant growth, and refresh the reservoir every few weeks depending on plant size, water use, and growing conditions.
Start gently, then adjust as plants grow
Many growing issues happen when plants are pushed too hard too early. A gentle, steady start is usually better than trying to feed heavily from the beginning.
As your plants grow stronger, develop healthy roots, and begin producing more leaves, they can usually handle a stronger nutrient mix.
What if I use an EC meter?
An EC meter can help you understand how strong your nutrient water is. It is not essential to get started, but it can be useful as your confidence grows.
The approximate EC values in this guide are designed as helpful home-growing ranges, not strict targets that need constant adjustment.
If you want to understand EC and pH more clearly, read our guide to pH and EC for home hydroponic growing.
Common feeding mistakes to avoid
Feeding your tower is simple, but a few common mistakes can make things harder than they need to be.
- Do not mix concentrated Part A and Part B directly together.
- Do not start young seedlings on full-strength nutrients.
- Do not keep adding nutrients every time the water level drops.
- Do not chase perfect EC numbers every day.
- Do not forget that light, water, and temperature also affect growth.
If something looks off, check the simple things first: light, water level, nutrient strength, root health, and whether the reservoir needs a refresh.
Feeding as your plants grow
How often your plants need water and nutrients can change depending on the season, light levels, temperature, plant size, and what you are growing.
Leafy greens and herbs often respond well to gentle, steady feeding. Fruiting plants may need more support over time, especially once they begin flowering and fruiting.
The goal is not to chase perfect numbers every day. The goal is to keep your tower steady, healthy, and easy to enjoy.
Frequently asked questions
Do I always use equal parts A and B?
Yes. FlowGrow nutrients are designed to be used in equal parts. If you use 40 ml of Part A, use 40 ml of Part B.
Can I mix Part A and Part B together first?
No. Never mix the concentrated nutrients directly together. Add Part A to water first, mix gently, then add Part B.
How much nutrient do I use for seedlings?
For seedlings, use 15 ml Part A and 15 ml Part B in a 15 L reservoir. This gives young plants a gentle start.
How much nutrient do I use for leafy greens and herbs?
For leafy greens and herbs, use 40 ml Part A and 40 ml Part B in a 15 L reservoir.
When do I switch from Grow to Bloom?
Switch to Bloom when plants begin flowering, forming buds, or fruiting. Grow is best for seedlings, herbs, leafy greens, and early plant growth.
Do I need an EC meter to feed my tower?
No. You can follow the FlowGrow feeding guide without an EC meter. An EC meter can be helpful later if you want to better understand nutrient strength.
Helpful next steps
Feeding becomes easier once you understand the basics. These guides can help you keep learning without making things feel complicated.
Understanding nutrients
Learn what hydroponic nutrients do and why FlowGrow uses a two-part A+B system.
Understand pH and EC
Learn what pH and EC mean and how they help you understand your nutrient water.
Care and maintenance
Learn the simple routines that help keep your tower running smoothly.
Need nutrients for your tower?
Explore FlowGrow Grow and Bloom nutrients for simple, balanced home hydroponic growing.
