Flowering stage in Cannabis plants week by week
Flowering initiation stage – week 1-3
From week 1-3 plants stretch and grow in size and height. This phase is also known as the transition phase, as plants experiment drastic changes these days. Plants stretch and may double their size in this phase. The female Cannabis plant starts blooming by producing pre-flowers, their pistils look like “white hairs”.
Towards the end of the third week, the plant starts forming its bud sites in the plant nodes (where the main stem and the branches meet). Look for clusters of female preflowers.
All those places where white pistils have been growing are future bud sites. If you accidentally cut the preflowers along with the fan leaves, there’s a chance that that bud stops growing. You may lightly defoliate your plant during this phase, but be careful not to touch or damage the forming bud sites.
Look at the color of the fan leaves and the general look of each plant to have a better idea of their health and needs. The fan leaves should be vibrant green, not too light nor dark. For example, yellow and discolored leaves may indicate a deficiency, while dark and clawing leaves may indicate nutrient burn. Track these changes as soon as you notice them for a better chance of diagnosing your plants correctly and in time to heal them!
It’s also important to check for pests, mold, and fungi before our plants start making their buds. Most importantly, to eliminate these at this point is usually easier than doing it later into the flowering stage.
Mid-Flowering stage – week 4-5
From week 4-5 plants stop growing in size and start growing, fattening their buds and darkening their pistils.
- Humidity levels need to be lowered to 40-50%
- It’s best to slightly lower temperatures in flowering
- Temperatures with lights on 18-26 ° C (avoid high temperatures)
Cannabis Mid-Flowering – week 4
At this stage, you should continue to train your plant if you started some weeks earlier and you should be seeing some changes. In addition, if you need to tie or move your plants, bear in mind that now they are putting all their efforts into growing buds, so any stress or damage may slow that process.
Remember to continue to move your lamp or plants so they maintain their adequate distance. Now your plants are growing at a fast rate and they need their feeding and watering schedule to be followed for optimal results.
It’s normal at this phase to see some old leaves yellowing and finally turning brown and falling. That’s because some nutrients are “mobile”, meaning that once the plant has absorbed them, they can be stored and distributed inside the plant as needed. So an old leave may “send” nutrients to the newer ones and once the plant doesn’t need that leave anymore, it lets it die and fall. If you notice lots of leaves yellowing or any changes in color or texture in the new or old leaves, check for nutrient deficiencies or burn!
Late flowering / Ripening stage – week 6 to harvest
In the last few weeks, buds gain the most weight. They are sticky to the touch and can be very smelly. You are very close to reaching your goal = harvesting!
- Bring down humidity levels: 35-45% if possible
- Increase the temperature difference (day/night)
- Temperatures with lights on 18-24 °C
- Start checking trichomes for signals or ripening to know when to harvest
- Remember to flush your plants 1-2 weeks before harvest
Most importantly, buds are now covered in trichomes, which are rich glandules for secreting THC and other cannabinoids. These are responsible for the stickiness in the colas. Depending on the strain and the breeding, these buds may have strong aromas, reminding of fruits, flowers, and spices for example.
In this stage of the Cannabis plant, pistils may show white, cream and brown colors. They also start curling inwards and they get covered in trichomes. Similarly, trichomes also change colors and you should pay close attention to these changes because they are one of the best clues for knowing when is the best time for harvesting.
Cannabis late flowering – week 7
Flushing your plants (week 8-10)
Flushing a Cannabis plant is basically to run a lot of water through its growing medium (soil, for example) to get rid of the excess of salt and mineral nutrients. This action forces your plant to use up any amount of nutrients previously absorbed. The result will be buds with better flavor and aroma. The excess of fertilizer in your Cannabis plant may result in buds which are harsh to the throat when smoked and
Flushing with clean, room temperature water will help to get rid of fertilizer excess in the soil.
Two weeks before harvesting is usually a good moment to start flushing your plants and watering with water only and no fertilizers until the harvesting moment.
Regarding the amount of water needed, a good rule is to calculate 3 times the volume of the pot. For example, if your pot is 5 liters, you can flush with 15 liters of water per pot. An easy way of doing this is carefully placing each plant in a big bucket, barrel, shower, or bathtub and add the water gradually to the soil, without drowning the plant. The excess water will slowly drain from the bottom of the pot.
A good visual sign is that, in the beginning, the water coming from the bottom of the pot will be dark and will gradually turn to a lighter color. If you don’t have a bathtub, you can do it inside the tent. Place a container (bucket or similar) under the pot for collecting the excess water, be careful or this may result in a bit of a mess. By running this process once in each plant, most of the salt buildup should flush away from the substrate.
Read the following article to learn exactly when to harvest your flowering plants, how to tell if they are ready by looking at trichomes and pistils, how to dry and cure your buds, and more! All explained in a simple way, with pics and a Step by step harvest guide.