When To Switch To Flower Nutrients: The Ideal Time

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One of the most important aspects of growing a marijuana plant is making sure that it gets enough nutrients, particularly during the flowering stage. But when really is the ideal time to switch to flower nutrients?

If you are growing indoors, then switching to flowering nutrients about one week after you make the light cycle switch is ideal. When growing outdoors, switching to flower nutrients a week or two after the summer solstice in June is recommended.

When To Switch To Flower Nutrients


When Should I Switch From Veg To Flower Nutrients?

What you need to know here is that cannabis plants grow in two main stages, well, technically three, although the seedling stage is irrelevant here.

First, your cannabis plant will spend a long time in the vegetative state, which is when all of the main foliage grows, the leaves.

The second stage is then the flowering stage, which as you can probably tell by the name of it, is when the flowers or buds grow.

Yes, a weed plant does still grow in size during the flowering stage, although now it will be mainly focused on producing buds and increasing THC levels.

Now, the nutrients required for vegetative growth are not the same as those needed during flower growth.

This means that you need to switch from veg to flower nutrients when the flowering stage begins, or just shortly after.

This does therefore mean that you need to know what the first signs of the flowering stage are.

First Signs Of The Flowering Stage

The first sign of the flowering stage in your weed plant is technically known as the pre-flowering stage, and this is going to last for about three weeks.

During the first week of flowering, one thing that you will notice is that the plant grows massively in terms of vegetative growth.

The plant gets a signal that winter is coming, which spurs it into overdrive, and it starts producing as much vegetative growth as it can to help carry the load of all of the flowers that are soon to follow.

You might see the phenotypes as much as double during this time. That said if you don’t have a trained eye, spotting this happening might be difficult.

During week two of the pre-flowering stage, you will notice that your cannabis plants start producing actual buds. You will see that the nodes between the fan leaves and stems start producing pre-flowers, just little buds.

If your plant is budding, you will see that the leaves around the branches bunch up and turn upwards, with small white pistils or hairs coming out of their centers.

If you happen to notice small sacks that look almost like bananas, instead of those white pistils, then it is a sign that you have a mall cannabis plant, something you definitely don’t want.

In the last week of the pre-flowering stage, you should notice that your cannabis plant has grown in size by up to 50%, but has now stopped growing in size.

You should also see those small hairs on the internodes, as well as a cola starting to grow on the top of the cannabis plant.

Then, when we get to week four, all vegetative growth should have stopped, with buds and pistils slowly getting bigger, which is the real start of the flowering stage.

Does It Differ When Growing Outdoors vs Indoors?

Yes, when your weed plant will start flowering will differ if we compare indoor and outdoor growing, but that said, the signs of flowering will still be the same.

In terms of indoor growth, what signals your plant to start flowering is the change in the light cycle, and since your plants are getting artificial light when this happens is up to you.

When you switch from a 24/0 or 18/6 light to dark schedule, over to the 12/12 hour light and darkness flowering lighting schedule, your indoor plant will start to flower.

However, if we are talking about an outdoor cannabis plant, this will start flowering after the summer solstice, on June 20, as this is when days start to get shorter, thus signaling the plant that winter is on the way and that reproduction needs to happen soon.

How Often To Fertilize In Flowering Stage

Of course, it really depends on how strong or concentrated the nutrients you are using are, but generally speaking, giving your weed plants nutrients either once or twice per week during the flowering stage is recommended.

If you want maximum results, try going for a twice weekly nutrient feeding schedule, although you do need to pay attention to your plant’s reaction after each dose of nutrients.

If your weed plants shows signs of nutrient burn, such as yellowing or blackening leaves, immediately stop giving your plants nutrients for at least one or two weeks.

Nutrient burn can be very dangerous if not immediately addressed.

When To Stop Adding Nutrients During Flowering?

You might be wondering why you would stop adding nutrients to your weed plants near the end of the flowering stage.

Well, this is because if you keep adding nutrients before harvest, your cannabis plant won’t have enough time to get rid of them before you harvest.

This means that harsh chemicals can be left over in the weed that you are going to smoke, plus it also leads to a bad taste and harsh smoke.

Therefore, if growing in soil, stop giving your weed plants nutrients about 2 weeks before harvest, and if growing hydroponically, about five days before harvest will do just fine.

Vegetative V.S Flowering Nutrients

What is important to note is that the nutrients required during the vegetative stage are not the same as those needed during the flowering stage.

Now, technically speaking, the three main nutrients your cannabis plant needs are always the same, the so-called NPK nutrients, which stand for nitrogen, phosphorus, and potassium.

During the vegetative growth stage, to help that stem and foliage grow big and strong, your weed plant is going to need lots of nitrogen. Nitrogen is the determining factor when it comes to the size of your plant, particularly during the veg stage.

If you buy veg fertilizers, you will see that they contain plenty of nitrogen, small amounts of phosphorus, and moderate amounts of potassium.

This ratio might look something like 10-5-8. Keep in mind that during the veg stage, nitrogen deficiency is the most common type of deficiency. If you see your plant yellowing or becoming light green, it’s likely not getting enough nitrogen.

When it comes to the flowering stage, your weed plant is going to need much less nitrogen and far more of the other two nutrients.

Nitrogen is needed for foliage growth, but the flowering stage is all about growing flowers or buds, as well as developing THC and other cannabinoids. For this, higher levels of phosphorus and potassium are needed.

A good ratio here would be something like 5-10-10.


You should now know exactly when to switch from veg nutrients to flowering nutrients when growing your weed plant, and yes, doing so is very important to the overall success of your growth.


My passion for the sticky icky started nearly a decade ago, and it all began when I first laid my eyes on the beauty that is the marijuana plant.

I cover all aspects of growing from equipment recommendations to plant health/care tips to help both new and experienced growers.