3 Week Old Autoflower (Here’s How Do They Look)

3 Week Old Autoflower

It’s been three weeks since you planted your autoflower cannabis seedlings.

You’ve been checking on them regularly, and now it’s time to see how they’re doing.

If you are new to growing cannabis, then this is the article for you. I will cover exactly what do a healthy 3 week old autoflower cannabis plant look like.

The first thing that you need to know about growing autoflowering cannabis is that it is not difficult at all. It is actually one of the easiest plants to grow in your garden, especially if you have never grown any type of weed before.

There are two main things that you need to take care of when growing autoflowering cannabis plants; temperature and light intensity. These two factors can be controlled easily by anyone who knows how to use a thermometer and set up some lights in their grow room or garden area.

We’re going to be taking a detailed look at what do a healthy 3 week old autoflower cannabis plant look like!

3 Week Old Autoflower

You may have seen pictures of cannabis plants at various stages of their life. If you’re new to growing, it can be hard to tell what’s normal and what’s not.

Here’s a picture of my three-week-old healthy autoflower plant:

3 week old Autoflower image source: ilgm

This picture is a perfect example of what a 3-week old autoflower cannabis plant should look like. The overall size of the plant should be about 1-2 feet tall and wide. The stem and leaves are thick and strong with vibrant green color. There are no signs of discoloration or other problems related to growth. The roots are strong and healthy as well.

In three weeks, the plants are short and bushy with many side branches. The leaves of the plant are few in number but they’re green and healthy looking. No yellowing or brown spots.

The plants have a few branches that are drooping or curved down. This is normal and will change as they grow older. You’ll want to keep an eye on this to make sure it doesn’t become too severe and affect your yields.

Autoflowering strains tend to grow between 2-5 nodes on each stem when they’re 3 weeks old, so if you’re seeing that type of growth on your plants, then congratulations! You’ve got some healthy little guys growing in there!

It’s important to remember that different strains of cannabis grow different numbers of nodes—it depends on the strain’s genetics.

7 Tips To Help Your 3-Week Auto Develop More Quickly

Image Source ILGM Grow Forum

1. Enough Nutrients

The first thing you should do is make sure that your auto has enough nutrients. It’s easy to forget about this step when you’re just starting out with growing autos, but it’s important! If your plant doesn’t have enough nutrients, it won’t be able to grow as quickly or as well as it could otherwise.

2. Water Moderately

Next, make sure that your auto gets plenty of water regularly. You want to keep the soil moist at all times until it is time for harvest—but don’t let it get wet all at once! This will cause root rot and other problems that may make harvesting difficult or impossible. Instead, try watering every few days so that there isn’t too much water in the soil at any given time.

3. Quality Soil

Use good quality soil when planting your auto plants! This will help them grow faster and stronger.

4. Correct Temperature or Humidity

You need to make sure that both of these are set correctly so that they don’t kill off any of the growth happening inside your home! The ideal temperature between 23 to 28°C during the day and around 13°C at night. While for humidity level – is between 40% and 60%.

5. Light Stress Training

If you want your plant to grow faster, it’s essential to give it LST! Light stress training is an easy way to do that. All you have to do is move your lights closer to the plant so that it gets less light than it usually does. This causes the plant to stretch out, which makes them grow taller.

6. Topping

This is another way to create more growth on your plants. Take off the top of your plant when it starts getting tall enough and stick it into soil with some nutrients added on top so that it can continue growing there!

7. Leaf Tucking

This is a great way to get a plant to start growing more quickly. Simply tuck the leaves in towards each other and then pull them out once they’ve been tucked in for about a week or two. You can also use this technique with cuttings, which will help them develop roots faster as well.

Recommended Nutrients for 3-Week Old Autoflower Cannabis

When it comes to nourishing autoflower cannabis plants, it can sound complex given the many different types of nutrients available. However, these young plants, especially at approximately 3 weeks, do not require a heavy diet. They primarily need a balance of key macronutrients along with certain secondary nutrients and micronutrients. Here’s a breakdown:


Autoflowering cannabis plants require the same primary macronutrients as regular cannabis – Nitrogen (N), Phosphorus (P), and Potassium (K). At 3 weeks old, the plant is in its vegetative growth phase, which is a crucial development stage of its life cycle.

  • Nitrogen (N): Nitrogen is vital for vegetative growth, helping the plant to produce proteins, amino acids, and chlorophyll, contributing to its vibrant green color.
  • Phosphorus (P): Although more crucial in the flowering stage, phosphorus plays an essential role in root development, energy transfer, and overall strength of the plant.
  • Potassium (K): Aids in maintaining the plant’s overall vigor, assists in photosynthesis, and helps to regulate stomatal opening and closing.

At week 3, the N-P-K ratio should favor nitrogen as this is key for the vegetative growth phase. A ratio of 3-1-2 is widely recommended. This means that Nitrogen should be the highest concentration, with an evenly balanced Phosphorus and Potassium.

Secondary Nutrients

Next to the macronutrients are secondary nutrients – Calcium (Ca), Magnesium (Mg), and Sulfur (S). They aren’t required in the same quantities but are equally crucial to your plant’s health.

  • Calcium (Ca): Improves the plant’s structure and cell integrity.
  • Magnesium (Mg): Assists in chlorophyll production and energy transfer within the plant.
  • Sulfur (S): Plays a role in creating proteins and aids in plant respiration.


Finally, the micronutrients, which are only needed in trace amounts, include Boron (B), Copper (Cu), Iron (Fe), Manganese (Mn), Molybdenum (Mo), and Zinc (Zn).

Remember, autoflowering cannabis plants typically have a shorter life cycle than regular cannabis plants, so it’s important to get their nutrition right from the start. Typically, during week 3, you should be starting to feed nutrients at approximately one-quarter strength, following manufacturer’s recommendations, and closely watching for plant response to avoid possible nutrient burn.

As always, it’s essential to monitor pH levels as well, for optimal nutrient uptake. A pH of around 6.0 to 7.0 in soil and 5.5 to 6.5 in hydroponics is typically recommended for cannabis plants.

Frequently Asked Questions

What Humidity Level Is Best For A Three-Week-Old Autoflower?

The ideal humidity level for a three-week-old Autoflower is between 40% and 60%. This range should not be exceeded 90% or fall below 20%, as either of these extremes can cause mold and infections.

What Temperature Level Is Best For A 3-Week-Old Autoflower?

The best temperature for a 3-week-old autoflower is between 23 to 28°C during the day and around 13°C at night.

Autoflowers are a type of cannabis plant that has been bred to start flowering automatically after reaching maturity. This means that you don’t need to worry about changing your light cycle or feeding it until it reaches maturity, which can be around 3 weeks after planting.

When growing autoflowers, you want to make sure that they have plenty of light and warmth, but not too much heat. A good rule of thumb is that if you can keep your hand on the leaves without burning them, then it’s probably safe for the plant. So when growing in an indoor environment, 27°C (80°F) should be fine; when growing outdoors, 20°C (68°F) should be fine.

Make sure that your plants get at least 18 hours of light per day (but no more than 24). Autoflowering strains tend to be sensitive to light changes and might not survive if exposed to bright light for too long before they’re ready to flower.

What Weeks Do Autoflowers Grow The Most?

Auto-flowering strains grow at their peak during the second half of their flowering period.

Most auto-flowering strains will grow the most between 5-6 weeks, though this can vary depending on the strain and growing conditions.

At What Week Do Autoflowers Stop Growing?

Autoflowers are known for their fast growth and high yields, but they also have a maximum height that they can grow to.

The vertical growth stops sometime during week 7, but the plant makes every effort to make the buds bigger.

How Tall Will Autoflower Get?

The answer to this question depends on the strain of autoflower you are growing.

Most strains will reach an average height of 50-100cm, but some may grow taller.

Genetics is a big contributing factor in determining how tall your plants will get. The strain’s growth conditions also play a role in how tall your plants grow, so make sure to provide plenty of light and water for optimal results!

What Week Do Trichomes Appear Autoflower?

Trichomes, which are the little crystals that grow on and around cannabis plants, start to form in the second or third week of your plants’ flowering cycle. They will continue to grow throughout the rest of their life cycle, but they’re most noticeable during the third or fourth week.


We hope you enjoyed this short guide on how do 3 week old autoflower look like. It’s interesting to see the diversity among the plants early in their growth process, especially when you consider that they all came from the same seed and will end up looking quite similar as they mature.

If you have any questions about your 3 week old autoflower plant grow, please let us know in the comment section down below, and I’ll be happy to answer them!

Happy growing!

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