The Athena Blended Bloom A & B is the two-part liquid base that feeds the Blended Line through the flowering stage. You get one bottle of A and one of B, used in equal amounts from the switch to flower through to the finish, with Athena's CaMg and PK added on top to fine-tune the feed. It's our best-selling Athena product, and the one most Blended growers reorder first.
Built for the flowering stage
Bloom shifts the balance of the feed the moment you flip. Where Grow A & B carries extra nitrogen for leaf and stem, Bloom is weighted toward phosphorus and potassium, the elements plants draw on most heavily as flowers set and fill. Athena blends it from mineral macronutrients and chelated micronutrients, so the elements stay available across a wider pH range and in any medium or water type.
It's a straight swap: when the Blended feed chart moves from veg to flower, Bloom A & B replaces Grow A & B as the base and carries you through to harvest.
Two parts, and why they stay apart
A and B come in separate bottles for a reason. The calcium in one part and the phosphates and sulfates in the other would react and drop out of solution if they met at full strength, locking up nutrients before they ever reached the plant. Kept apart and added one at a time to water, they stay fully dissolved.
So the routine is simple: water first, then Bloom A, stir, then Bloom B, stir. Always the same amount of each, never mixed together straight from the bottle.
Tune it with CaMg and PK
The Blended Line runs on variable EC, which means feed strength follows Athena's chart and changes week to week through flower. Bloom A & B sets the base; CaMg and PK are what you use to adjust it. CaMg lifts calcium and magnesium without changing the base ratio, which matters most on RO or soft water. PK adds phosphorus and potassium through the heavy middle weeks of flower.
Full specifications
| Manufacturer | Athena (Los Angeles, USA) |
| Line | Blended Line — variable EC |
| Type | Two-part liquid mineral fertiliser |
| Bloom A N-P-K | 4-0-5 |
| Bloom B N-P-K | 0.7-6-5 |
| Stage | Flowering — replaces Grow A & B at the flip |
| Mixing | Equal parts A and B, added separately to water |
| Dose rate | Per week of flower — see the Athena metric feed schedule (PDF) |
| Sizes (sold as A + B set) | 3.78 L (1 US gal) each · 18.9 L (5 US gal) each |
| Compatibility | All media and water types; all dosing and drip systems |
| Storage | Sealed in original bottle, 7–29°C (45–85°F) |
FAQ
Do I get both bottles?
Yes. Each order is a set: one Bloom A and one Bloom B, both in the size you choose. You always need both, in equal amounts.
Do I still need Grow A & B?
For the vegetative stage, yes. Grow A & B is the veg base and Bloom A & B is the flower base. You run one or the other, not both at once, switching over when the feed chart moves into flower.
Can I mix A and B together in a jug before adding water?
No. Always add each part to water separately and stir between them. Combined at full strength they react and fall out of solution.
Do I have to use CaMg and PK as well?
Bloom A & B is a complete base on its own. Most growers add CaMg, especially on RO or soft water, and use PK through mid-to-late flower as the chart calls for it. Start with the base and the chart, then add the others as your water and plants need them.
Which size should I buy?
The 3.78 L set suits one or two home tents for a run or more. The 18.9 L set is for multiple tents, larger rooms or anyone dosing through an injector who wants the lowest cost per litre. If you're unsure, tell us your tent size and reservoir volume and we'll work it out with you.
Can I use it in DWC or RDWC?
Yes. Blended is the Athena line for deep water culture — Athena publishes an RDWC procedure and addback calculator for it. The Pro Line has no DWC procedure, so if you're running roots in a reservoir, Blended is the one to use.
Can I use it with the Athena Pro Line?
No. Blended and Pro are separate systems with their own feed charts. If you're running Pro Core, use Pro Bloom in flower instead.