When to Start Bloom Nutrients

When to Start Bloom Nutrients in Your Indoor Grow


You’ve had a successful veg with flourishing plants full of growth, foliage and deep roots. Now it’s time to flip into flower to get booming colas.

Today, I’m going to demystify one of the crucial aspects of cannabis cultivation based on my decades of experience running commercial gardens and small home grows. Let’s look at when to start bloom nutrients in your indoor grow.

When to Start Bloom Nutrients
When to Start Bloom Nutrients

A Guide to the Cannabis Flowering Phase and When to Start Bloom Nutrients

The cannabis flowering phase is where all your hard work pays off as your plant transforms from a humble leaf factory into a cannabinoid-producing powerhouse. It’s a time of transition, not just in appearance but also in the plant’s nutrient needs. If you’ve ever wondered when to switch to bloom nutrients indoors, this is the moment.

Cannabis plants shift their nutrient needs when they enter the flowering stage. They demand less nitrogen and more phosphorus and potassium. Both crucial macro nutrients for developing large, dense, sticky buds. With the right cannabis nutrients, you’ll coax out the rich flavors, potent aroma, and top-shelf quality your plants are capable of. You want to use nutrients that help your plants reach their full genetic potential!

Switching from Veg to Bloom

When you learn how to manage your plants, understanding when to switch from grow to bloom nutrients is super important. The flip occurs when you switch your lights to 12/12, which initiates the flowering stage.

You don’t want to rush this process. Take your time and veg your plants to the size of your grow space/room and remember that “a grower’s best tool is patience”. If you flip too early, the plant may not be strong enough to support a lot of large flowers so wait for your plant to be strong and top your cannabis plant to get multiple large colas.

Now, what if you’re growing outdoors or wondering when to switch to bloom nutrients outdoors? In this scenario, your plants will naturally transition as the days shorten, typically in late summer to early fall, depending on your latitude.

Can I keep my plants in eternal veg?

Yes! If you are growing a mother and want to make cannabis clones, you should keep the mother plant in veg without flipping her to flower. You do that by never changing the light schedule to 12/12.

You normally want to keep a mother in veg because you want identical clones of a specific phenotype. When growing a cannabis strain from seed (learn how to germinate seeds) you get plants with different characteristics. Some of the plants will be “winners” that you want to clone. Those are the mothers you keep!

Triggering the Reproductive Cycle in Early Cannabis Flowering

The early flowering stage, which usually spans the first three weeks of flower, is the right time to start feeding bloom nutrients. Think of it like a teen entering adulthood, they need a lot of food to support their growth.

Weeks 1-3

During these first crucial weeks, phosphorus and potassium intake increase, while nitrogen uptake decreases. Your plants’ dietary change is driven by the switch from vegetative growth to the reproductive stage. Here’s where your bloom nutrients enter the game, giving your plants the fuel they need to produce big flowers.

Lighting plays a significant role too, with a 12/12 light/dark cycle being the gold standard for indoor growers.

Weeks 3-4

This period can be tricky. Your plants have started flowering and they still need a small amount of nitrogen to maintain their overall health. But be careful not to overdo it, as too much nitrogen can hinder bud development.

We recommend using our simple 2-part base nutrients with the perfect ratios. It gives all macros needed through all the stages of the growth cycle in just the right proportionate balance for your plants to thrive. 

Weeks 4-6

In weeks 4-6, your plants are in full bloom and require different nutrients. This is the best time to use bloom boosters like BudTone:PK to maximize bud development.

Weeks 6-8

By now, your plants are preparing for harvest, and nutrients should be gradually reduced to prevent chemical flavors in the final product.

This is a good time to flush your plants, essentially giving them plain water along with Amplify (microbial inoculant) for the last week or two to remove any residual nutrients. Read our article on how to flush cannabis plants here.

How to grow bigger buds

Vegetative vs. Flowering Nutrients Including Bloom Boosters and Microbes

During the vegetative phase, your cannabis plants crave nitrogen to fuel their rapid leaf and stem growth. But when they transition to flowering, their nutritional needs change. This is when bloom nutrients become essential.

When considering bloom nutrients for your outdoor grow, the best bloom nutrients for outdoor grow situations are often those tailored to the unique needs of flowering cannabis plants. Organitek’s nutrient lineup offers comprehensive solutions that cover all stages of growth and can provide excellent results when used correctly.

Can you use bloom nutrients in veg?

Generally, no. Using bloom nutrients too early can lead to cannabis nutrient deficiencies and imbalances that might stunt your plants. Each phase has its specific needs, and it’s crucial to provide the right nutrients at the right time.

At Organitek we use an easy 2-part system that is designed to work in tandem throughout veg and bloom. You simply adjust the ratios of Channel 1 (roots, frame and foliage) and Channel 2 (flowers) based on the feed chart to give your plants the optimal nutrient balance through the full grow cycle.

To wrap it up, remember that understanding when to start using bloom nutrients in your indoor grow can significantly impact your final harvest. Grow smart, grow patient, and grow with love!


Cannabis Grow Series

This article is part of the cannabis grow series where we want to teach you how to grow cannabis step-by-step in a simple and effective way. Explore the full series here!


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