How Much Nutrient Should I Use?
Feeding your FlowGrow tower is simple once you know the basic rhythm: use equal parts Part A and Part B, mix nutrients into water, and choose the strength that suits the plants you are adding to your tower.
FlowGrow feeding guidance is based on the recommended 15 litre working reservoir. This keeps measuring easy across all FlowGrow tower sizes and gives the pump enough water to circulate properly without overfilling the base.
Most home growers do not need a complicated staged feeding chart. The main thing is knowing when to use the normal tower mix, when to start gently, and when Bloom nutrients are useful for flowering or fruiting plants.
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 short version: for most everyday tower growing, use 75 ml Part A + 75 ml Part B in 15 L of water. Use 40 ml + 40 ml for very young plants while they settle in and begin growing.
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 75 ml of Part A, you also use 75 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
Use this table as your practical home-growing guide. It is designed around the way most people actually use their tower: starting with purchased seedlings, young plants, leafy greens, herbs, strawberries, chillies, or compact fruiting plants.
| Use | Part A | Part B | Best used for |
|---|---|---|---|
| For very young plants | 40 ml | 40 ml | A gentle starting mix while young plants settle in and begin growing. |
| Everyday tower growing | 75 ml | 75 ml | Most purchased seedlings, leafy greens, herbs, young established plants, and everyday tower growing. |
| Bloom heavier fruiting option | 105 ml | 105 ml | Mature flowering or fruiting plants that are growing strongly and receiving good light. |
The everyday tower mix is the main mix most growers will use. The 40 ml mix is there for very young plants while they settle in, not as a long-term feeding rule for every plant.
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:
- purchased seedlings settling into the tower
- leafy greens
- herbs
- early plant growth
- plants focused on leaves, stems, and roots
For most Grow use, mix 75 ml Grow A + 75 ml Grow B into 15 L of water. For very young plants, start with 40 ml Grow A + 40 ml Grow B first, then move to the recommended mix as growth strengthens.
When should I use Bloom nutrients?
FlowGrow Bloom nutrients are used once plants begin shifting into flowering and fruiting.
Use Bloom nutrients when plants begin:
- flowering
- forming buds
- setting fruit
- moving beyond leafy growth
Bloom is useful for plants such as strawberries, compact tomatoes, and chillies once they begin moving into their flowering or fruiting stage.
For standard Bloom feeding, mix 75 ml Bloom A + 75 ml Bloom B into 15 L of water. For mature fruiting plants that are growing strongly and receiving good light, you can increase to 105 ml Bloom A + 105 ml Bloom B in 15 L.
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 fresh seedlings start on the normal mix?
Often, yes. Many garden centre seedlings are already developed enough to begin on the normal FlowGrow tower mix, especially leafy greens and herbs that look healthy and have a reasonable root system.
Once seedlings have their first true leaves and are starting to grow actively, they can begin using nutrients. Start with the gentle mix, then move to the recommended mix as growth strengthens.
For very young plants: use 40 ml Part A + 40 ml Part B in a 15 L reservoir. Once plants look settled and are growing steadily, refresh or top up according to your routine and move to the normal 75 ml + 75 ml tower mix.
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. Plants use water and nutrients at different rates, and water can disappear faster during warm weather or strong growth.
For most home growers, the routine is to keep water topped up, observe plant growth, and refresh the reservoir every few weeks depending on plant size, water use, season, and growing conditions.
Start steady, then adjust as plants grow
The aim is not to push plants as hard as possible. It is to keep your tower steady, healthy, and enjoyable to use at home.
Good light, regular water top-ups, balanced nutrients, and simple observation matter more than constantly changing the 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.
FlowGrow’s normal Grow mix of 75 ml A + 75 ml B in 15 L has measured around EC 1.0 to 1.1 in real-world FlowGrow testing. Your own reading may vary depending on water quality, temperature, meter type, and growing conditions.
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 straightforward, 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 push very young plants too hard too quickly.
- 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, temperature, and root health 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
Leafy greens and herbs usually respond well to steady Grow feeding. Fruiting plants may need Bloom support once they begin flowering or fruiting, especially when light levels are strong.
More nutrient is not always better. If light is weak, plants may not be able to use stronger feeding well. That is why a sunny indoor spot, sheltered outdoor position, or strong natural light matters so much for fruiting plants.
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 75 ml of Part A, use 75 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.
What is the normal FlowGrow tower mix?
For most everyday tower growing, use 75 ml Part A and 75 ml Part B in a 15 L reservoir.
When should I use the gentle mix?
Use 40 ml Part A and 40 ml Part B in 15 L for very young plants while they settle in and begin growing.
When do I switch from Grow to Bloom?
Switch to Bloom when plants begin flowering, forming buds, or fruiting. Grow is best for leafy greens, herbs, young plants, and early plant growth.
How much Bloom nutrient should I use?
Use 75 ml Bloom A and 75 ml Bloom B in a 15 L reservoir as the standard Bloom mix. For mature fruiting plants growing strongly in good light, you can increase to 105 ml Bloom A and 105 ml Bloom B.
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 routines that help keep your tower running smoothly.
Need nutrients for your tower?
Explore FlowGrow Grow and Bloom nutrients for balanced home hydroponic growing.
