Nutrient Basics: A&B vs. 3-Part

Nutrient Basics: A&B vs. 3-Part

When it comes to growing, there is an overwhelming amount of products.


Products from fertilizers to nutrients to additives, all with the claim of providing the best. It can get confusing when you see a four bottles of nutrients, but two are A&B nutrients and two are two-part nutrients.

One of the first differences between these two nutrients is the separation and quantity of specific nutrients. Every nutrient (except a select few) has a specific NPK (nitrogen-phosphorus-potassium) ratio. Plants in different growth phases can require or benefit from higher or lower levels of specific elements, and these nutrient products aim to find the perfect ratio for your grow during its different stages of growth.

A&B Nutrients


A&B nutrients are split into two separate containers, each containing specific nutrients and amounts of the NPK ratio.

Plants require specific macro and micro-nutrients in order to thrive much like humans. In A&B nutrients, the A bottle may have Nitrogen and several micronutrients. The B bottle will have phosphorus and potassium with the remaining micronutrients.

There are additional nutrients you can use during the flowering stages to add more flavors or smells, but you can grow a plant from seed to harvest with just an A&B nutrient line. Most home-growers will use just an A&B as it’s less bottles, less measurements, and effective.

1, 2 and 3 Part Nutrients

One to three part nutrient products will have nutrients split up depending on how much a grower wants to be involved. A one part product will have a slurry of every single nutrient in one bottle. All it needs a good shake before use to deliver all the nutrients your plant needs.

A two part nutrient is nearly identical to an A&B product, as it is two separate containers that hold the amounts of NPK and other nutrients that, when combined, create a full product. They are only separated to avoid chemical interactions between elements and nutrients.

A three part nutrient is like a two part nutrient split into three containers, so instead of more concentrated quantities in two or one bottle, you have less concentrated product in three containers. Each nutrient bottle can be utilized separately during a phase of growth (e.g veg and flower) or combined throughout the entire growth process to develop the right mix.

In most cases, the micronutrient bottle will be used throughout the whole process, while the veg nutrient will only be used at the beginning, and the bloom nutrient at the end.

These nutrients allow a grower to experiment with their measurements to see what works best for their grow. However, there is a higher risk of messing up measurements when you have to individually measure and combine three separate products.

Is there a difference?

In their respective uses, no. In their storage and application methods, yes. Whether you use an A&B nutrient line or a three-part nutrient line, your results can be identical if your measurements equal out.

However, unless you know what you are doing and are confident in your abilities, using a basic A&B nutrient is better if you’re just starting out. If you want to mess around, make your own mixes and see what works best, then go for a three-part. But don’t be surprised when something goes wrong because you accidentally used too much of one part and not enough of another.

If you want to know more about nutrients, the best products, or which nutrients would be best for your grow, just come into Cultivate and we’ll get you the perfect product.

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