MILLSC4 20LTR

Flowering Booster with Seaweed & Macronutrient Blend, 20L

Flowering plants put heavy demand on flower site development and fruit set that a base nutrient feed alone doesn't fully cover once bloom is underway. Mills C4 is a flowering booster and activator combining macronutrients, protein hydrolysate, humate, and seaweed extract with a blend of phosphorous compounds and trace minerals, formulated to layer onto the Mills base feed during flowering.

This 20L size of C4 fits a mid-size grow running several rooms or a longer feeding schedule.

Key Features & Benefits

• Macronutrient & Seaweed Blend — combines macronutrients, protein hydrolysate, humate, and seaweed extract.
• Phosphorous Compound Complex — adds a blend of phosphorous compounds and trace minerals for the flowering stage.
• Supports Flower Sites & Fruit Set — formulated with organic and mineral elements to support flowering development.
• Supports Sugar & Oil Production — formulated to support the plant's own sugar and essential oil production.

Who Should Use Mills C4

Growers in the flowering stage who want a booster layered onto the Mills base feed to support flower sites and fruit set.

About Mills C4

Mills Nutrients designs its full feeding system, from the Basis A and B base feed through Start-R, C4, Ultimate PK, and Vitalize, at a dedicated research and production facility in the Netherlands. C4 is the system's flowering-stage booster, built to layer onto Basis A and B once bloom begins.

Frequently Asked Questions

What is Mills C4 used for?

It's a flowering booster and activator formulated to support flower sites and fruit set once bloom is underway. It's meant to layer onto the Mills Basis A and B base feed rather than replace it.

What is in Mills C4?

It combines macronutrients, protein hydrolysate, humate, and seaweed extract with a blend of phosphorous compounds and trace minerals. That combination is what sets it apart from a straight phosphorus-potassium bloom booster.

When should I use C4?

Use it during the flowering stage, alongside your regular Basis A and B feed, to support flower site development and fruit set. It isn't intended for the vegetative stage.

How do I apply Mills C4?

Add it to your reservoir alongside your regular Basis A and B feed, following the label rate for your growing medium. Mills' nutrient calculator can help dial in the combined concentration once C4 is layered onto the base feed.

Which size should I choose?

Home growers typically start with the 1L or 5L container, mid-size operations move up to 10L or 20L, and larger flowering rooms order the 60L or 200L size. Since C4 only runs during flowering rather than the whole cycle, sizing it to one bloom cycle's worth of use is a reasonable starting point.