Short answer: An A+B fertilizer is a main fertilizer split into two bottles that you mix into water one after the other. A one-part fertilizer has everything in one bottle. Choose A+B if you want very concentrated nutrients and a clear base for hydro or coco. Choose one-part if you want the simplest routine. Both work when you follow the feeding chart.
If you grow in hydro or coco, you will see two kinds of main fertilizer: A+B fertilizer and all-in-one, one-part fertilizer. This guide explains what A and B mean, how the two types differ and how to choose for your plants. It uses Bionova products as the example, but the logic applies to any hydro cultivation setup.
What is an A+B fertilizer?
An A+B fertilizer is one main fertilizer that is split over two bottles. Bottle A and bottle B together give your plant the full feed. You never use one without the other.
Bionova Nutri Forte A+B Hydro is an example. It has a concentration of 1:600 and an NPK of 8-0-0 for A and 0-6-12 for B. The same A+B design is used in Coco Forte A+B for coco.
The two parts are kept apart in the bottle. This lets the nutrients stay concentrated and stable. Once you dilute them in water, they work together.
What is a one-part fertilizer?
A one-part fertilizer has all the main nutrients in a single bottle. You measure one dose, add it to the water and you are done. The Bionova Hydro Supermix works this way. It has a concentration of 1:400 and an NPK of 7-4-5, and it is made for both growth and flowering.
A+B vs one-part: the main differences
| Criteria | A+B fertilizer | One-part fertilizer |
|---|---|---|
| Bottles to buy and store | Two, always used together | One |
| Mixing steps | Add A, stir, add B, stir | Add one dose |
| Concentration (Bionova example) | 1:600 (Nutri Forte) | 1:400 (Hydro Supermix) |
| Risk of a mixing mistake | Higher: wrong order or unequal parts | Lower |
| Best for | Growers who want a concentrated hydro or coco base | Growers who want the simplest routine |
Neither type is better in every case. The right choice depends on how you like to work and which substrate you use.
How to mix an A+B fertilizer
- Fill your vessel with water.
- Add part A and stir well.
- Add part B and stir again.
- Add stimulators or minerals after the main fertilizer, as your feeding chart says.
- Measure EC and adjust the pH. For hydro, the feeding chart advises a pH of about 5.5 to 6.0.
Always add A and B to the water one at a time. Never pour the two concentrates together. If you use Silution, add it to the water first, stir and wait 30 minutes before you add the main fertilizer.
When to choose A+B
Choose an A+B fertilizer if:
- you grow in hydro or coco and want a concentrated main fertilizer;
- you do not mind one extra step when you mix;
- you use soft or reverse osmosis water and follow a chart that adds Ca 15 and MgO 10 on top.
When to choose one-part
Choose a one-part fertilizer if:
- you are new to hydro cultivation and want fewer steps;
- you prefer to keep one bottle and one dose;
- you want to avoid mixing the wrong order.
Doses and EC: use the feeding chart
The dose per week is different for each product, so do not copy numbers from a different fertilizer. Use the official chart for the product you have: see the Bionova feeding charts. Change the dose in steps of about 10%, wait a few days and look at new growth before you change again. If you are new to charts, read our guide to reading a feeding chart.
Which products to use
For hydro, start with Nutri Forte A+B Hydro or Hydro Supermix. If you want to try the range first, the Hydro Exploration Pack is a good start. See the full hydro collection for everything in one place.
FAQ
What is an A and B fertilizer?
It is one main fertilizer split into two bottles, A and B. You add both to the water, one after the other, to give the plant the full feed.
Can I use only part A or only part B?
No. The two parts belong together. Using only one gives your plant an incomplete feed.
Is an A+B fertilizer good for hydro cultivation?
Yes. A+B fertilizers such as Nutri Forte A+B Hydro are made for hydro and for irrigation systems. Follow the hydro feeding chart for the dose.
Which is easier for a beginner, A+B or one-part?
One-part is easier, because there is one bottle and one dose. A+B only adds one mixing step, so beginners can use it too if they follow the order.
