Weed Flowering Week By Week (Complete Guide)

Flowering time is the best!

This is when your plants begin to grow buds and you finally get to see the results of all your hard work.

But you need to make sure you provide your plants the right conditions, to maximize bud growth and potency.

This means the correct temperature, humidity, nutrients, and light.

Our weed flowering week by week guide will help you get it all right. As usual, we will keep things as simple as possible for now.

 

Cannabis Plant Needs During Flowering

Before we get into the details of each week of the bloom period, let’s take a look at what your plants will need during flowering, in terms of lighting, nutrients, temperature, humidity, and more.

 

Flowering Stage Light Requirements

Your cannabis plants will need much more light during flowering than they do during veg, to fuel all that bud growth. To maximize the size of your buds, you will want each square meter of canopy to get 800 to 1000 umols of light, or more.

If you have been running your lights dimmed down, now is the time to dial up the power. If your lights have been hanging higher above your plants, now is the time to lower them. Otherwise, you could end up with smaller buds or buds taking forever to mature.

If you have already been running your lights at full power during vegging, you will want to add some more lights. You could flower with the same amount of light as you use for vegging, but your plant will not produce buds as large as it would with more light.

 

Flowering Stage Nutrient Requirements

Marijuana plants need different nutrients during blooming than they do during vegging. The biggest difference is that they no longer need nearly as much nitrogen during the flowering stage of growth.

The best way to ensure your plants get the exact right nutrient mix is to use nutrient solutions made specifically for cannabis, like the ones I recommended. Follow the guidelines on the packaging, but cut the recommended amounts in half, at least at first.

You can increase the amount to 3/4 of the recommended amounts, if your plants are growing rapidly and want more.

But you don’t just want to switch from veg nutrients to flower nutrients all at once. It is best to switch over gradually,m to avoid shocking your plants, which will stall growth for a bit.

We’ll cover this more below in the week-to-week guide, but you’ll want to keep giving your plants the growing solution for the first week of flowering, and then start using the bloom boosters a week into the flowering stage.

Around the 4th week of the bloom stage, you want to begin reducing the amount of nutrients gradually. During the last few weeks before harvest time, you should no longer give your plants any nutrients.

This will cause your plants to begin dying. This is fine. They are using all of their energy to grow buds and letting everything else die away.

Your plants will not use any nutrients you give them at this stage. This means that the nutrients end up being stored in the buds, which makes them taste bad.

 

Bloom Stage Temperature And Humidity Requirements

Mold and mildew can become a problem during flowering, so you want to keep the humidity lower than during vegging. Ideally, you want your tent to have a relative humidity of 40 to 50% during the beginning of the bloom stage, and between 40 and 45% during the final few weeks.

The temperature should be lower as well, but there is a fairly large range you can keep it at. As long as you keep it between 65 and 80° F (18 and 26° C), your plants will be fine.

Due to the heat from the additional lighting output, you will definitely need to have a ventilation system running at this point, in order to maintain the proper temperatures.

 

Weed Flowering Week By Week

In general, the flowering stage lasts around 7 to 9 weeks. It depends on the strain and some can take longer than 9 weeks or less than 7. We’re going to take a look at the first 5 weeks, week by week.

Then we’ll finish with the final few weeks. If you have a strain that takes longer than that to get through the flowering stage, nothing really changes, except for the timing. Things that usually happen in, say, week 3, will happen in a later week instead.

 

Week One

The first week of flowering is often referred to as the “stretch phase”. This is because your plants will grow rapidly and stretch to up to double their height. They also grow a lot more leaves.

But they can’t grow rapidly without food. During the first week of flowering, you actually want to continue giving your plants growth (vegging) nutrients, instead of switching to flower (bloom) nutrients. But go ahead and increase the amount you feed.

 

Week Two

The second week of the bloom stage is when you switch up your plant food. Start giving your plants flowering nutrients. It is best not to switch at once, but to gradually reduce the amount of growth nutrients and increase the amount of flowering nutrtients.

Adhere to the manufacturer’s nutrient schedule, but start with half the amount indicated. Increase as needed, if your plants appear to not be growing quickly.

Week two is also when your plants will reveal their sex. This article covers how to tell is you have a male or female cannabis plant. That said, if you are following my advice, you will have used feminized seeds, so there is no need to worry about this.

The second change is that your plants will begin showing their sexes so you can tell if you have a male or female plant.

 

Week Three

The rapid growth you saw during the first two weeks of flowering should slow down considerably during the third week. Most strains will have grown around 50% larger in the previous two weeks.

Instead of new plant growth, week three brings with it some bud growth. The reason your plants slow down their growth considerably is that they are now using all of their energy to grow buds.

To fuel that bud growth, your plants need their blooming nutrients. In week two, you started giving bloom nutrients, but in week three, you should be done with growth nutrients and be feeding only bloom ones.

As you increase the amount of flowering nutrients you give your plants, keep an eye out for signs that they are getting too many nutrients. The first sign of nutrients excess is discoloration in the tips of the leaves.

 

Week Four

By the time your plants enter the 4th week of flowering, plant growth has probably stopped completely, bud bud growth should really be taking off.

The buds will continue to grow larger and they should also have white hairs sticking out now. Increased trichome production means they will begin giving off a powerful smell as well.

Continue feeding bloom nutrients as before, but start to reduce the amount you feed gradually. If you notice any larger fan leaves blocking light from reaching buds, you can go ahead and trim them off.

 

Week Five

Week 5 is all about the buds. They will continue to grow and new ones will also form. You will also notice a much more pronounced smell of cannabis. You’ll really get to see why you needed that charcoal filter.

This is generally the week you want to stop feeding nutrients at all, in order to avoid them imparting a bad taste on your buds.

During this week, you may notice that some of the white pistil hairs start to darken. Some trichomes may also start to become cloudy.

This means that your buds have reached the point where you could begin harvesting them. But you will probably want to hold off a bit longer, at least if you want to harvest them when they contain the maximum amount of THC.

 

The Final Weeks

As mentioned, you could harvest in week 5. And sometimes the plants reach their maximum THC level during that week. But most of the time, it happens in weeks 6 or 7.

You will notice the hairs on your plants become darker and the trichomes become milky. This indicates that it is almost time to harvest your buds. You want to harvest when 50 to 75% of the hairs are dark, or most of the trichomes are cloudy.

 

Week By Week Guide To Flowering Cannabis: Final Thoughts

The flowering stage of cannabis cultivation is a critical period where the plant’s needs shift significantly from the vegetative stage. Proper lighting, nutrient management, and environmental control are essential to maximize bud growth and potency.

Always keep an eye on your plants so that you can see any problems early and address them. if you follow this guide, you should get good yields from your plants, even on your first grow. Then we will fine-tune some things on subsequent grows to really maximize those yields.