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The Best Guide for Growing Autoflowering Outdoors

Mike Wilson
Mike Wilson
cannabis free

The autoflowering strains are descendents of Ruderalis genetics that originally come from Russia and have the ability of flowering independently of the hour of light. In other words, the autoflowering seeds are independent of the photoperiod and super easy to grow outdoors and indoors, making them ideal for beginning growers.

Autoflowering cannabis seed plants generally begin to flower after 4 or 6 weeks automatically and their buds are usually ready to be harvested after 45 to 55 days of flowering, depending on the genetics of each strain. For this reason, the autoflowering strain is one of the faster seeds for growers of all types from an enthusiast of cannabis to commercial growers. If you’re looking for a fast harvest, the autoflowering cannabis seeds are perfect for you.

Today, many autoflowering seeds exist and here at Blimburn Seeds, you will find the biggest stock of this strain for growing in your outdoor garden. Some of the most popular strains are: Grandaddy Purple Auto, Gorilla G4 Auto, Cream Auto and more. This type of strain is ideal for the growers that want to grow outdoors in the summer, producing strong plants in a short time with great buds.

The best conditions for growing autoflowering outdoors

outdoor weed

Light Cycle

You know that the autoflowering strain does not depend on a light cycle for growing and flowering, but the most possible light hours are necessary for having a great plant and good yields.  The optimal hours of light for autoflowering are 20 hours and 4 hours of darkness during growth. While some specialists say that with 18 hours of light and another 6 hours of darkness during flowering, the plant feels comfortable.

Optimal climate

The adaptability of autoflowering strains is remarkable, however, at Blimburn Seeds, we recommend that you start growing your autoflowering cannabis seeds between mid and late spring. In this way, your marijuana plants will enjoy a better temperature and more hours of light outdoors. On the other hand, you will prevent the last rains of the season from affecting the growth of the specimens, ensuring optimal development.

Growing in winter or summer?

It is necessary to adjust the levels of fertilizers and irrigation in hot summer climates because the plants tend to consume more nutrients and therefore more water in order to grow and flourish correctly. Another important point is that you will have to apply techniques such as LST in order to promote good air circulation and prevent the appearance of pests and diseases in the plants which are generally caused by excess humidity.

Now, if you are going to grow in winter, you must bear in mind that low temperatures will make your plant grow slower and probably smaller as well. You must also factor in that the hours of light are less and for this reason, the plant will not reach its maximum performance point. In addition, it is good to point out that the temperature of the water is fundamental because if you irrigate with water that is too cold (below 10ºC) the roots of your plants can suffer and literally block or freeze.


Regarding humidity, it is good to stay at 60% because small plants prefer a little more humidity for their development. Remember that excess humidity affects the seedlings because it prevents them from breathing and therefore from developing.


For this reason, we recommend using a thermo-hygrometer, a device that measures humidity and ambient temperature and also analyzes the humidity levels and temperature. For outdoor growth, you can find this information on the internet. This will help you to have parameters and to be able to develop a cultivation plan to avoid problems in the future.

Growing Space

In general, the autoflowering plant doesn’t have a big development. For this reason, you do not need a big space between plants like with the female or regular plants. Is recommended to use 3 gallon pots and a space of 35-40 cm between every plant. You can also defoliate in the early stage of flowering, giving more power to the top part and increasing the size of the buds. 

The top strains

First of all, we recommend Granddaddy Purple Auto because it is a super, mostly indica strain that is easy to grow and fast from germination to harvest. THC levels range from 16%-19% and flowering lasts 49-56 days. This indica strain is ideal for outdoor growth during the summer, starting the process between mid and late spring. In addition, it is good to be attentive to the humidity levels in order to avoid losing the harvest due to possible fungi or diseases.

Grandaddy Purple Marijuana Plants

You can apply LST techniques to Grandaddy Purple Auto plants to ensure that the air circulates well between its branches. This will help you obtain good harvests, ranging from 80 gr – 120 gr outdoors, achieving maximum yields in quantities of 10 to 20 plants and up for patios and gardens.

We emphasize that Gorilla G4 Auto is an explosive, fast, and mostly sativa automatic with a great effect due to its high THC levels that are between 18% – 24%. This strain delivers fun, energetic effects with a relaxed finish. Another important point is that outdoors, it only takes between 8 and 9 weeks from the time the autoflowering seeds are sown until the day of harvest, especially for lovers of sativa strains of marijuana who want fast harvests.

Gorilla G4 Auto

For those looking for well mixed flavors, Gorilla G4 Auto delivers buds with pine and fruit flavors, a real refreshing treat on your palate. However, that is not all because outdoor harvests range from 70-300 gr, achieving excellent yields if it is grown in the peak of summer when the days are warmer and the daylight hours last longer.

Do you like extra sweet strains? Well, Cream auto is a real treat for your mouth. These autoflowering marijuana seeds are characterized by being mostly indica, compact in size, and producing super sweet buds. Cream Auto is a cross between Cream Caramel x Deimos Auto x Lowryder. For the same reason, you are also guaranteed those intense hits that will leave you on the couch, ideal for people those who want to relieve body pain.

Cream Auto Blimburn Seeds

The life cycle is fast, only taking 65 to 75 days from sowing to harvest and yields of 80-100 gr outdoors. The buds develop good levels, of THC ranging from 16%-18% and to top it off, CBD levels reach up to 1.5%, making it an ideal strain for medicinal users.

Growing autoflowering marijuana plants step by step

Just like regular or feminized cannabis strains, autoflowering marijuana strains require some care and concern from gardeners when growing. That is why we leave you with a simple step by step guide so you know how to grow your autoflowering cannabis plants outdoors. These tips, complemented with those already given, will make you a first-class breeder.

Girl Scout Cookies Marijuana Plant Outdoor

Girl Scout Cookies Auto 

Step 1. Germination

The first step is to germinate the seeds which sprout with their main root after 24 to 72 hours of starting the process. Next, prepare the substrate where the germinated autoflowering cannabis seed will be planted and use fungi that help the development of the roots such as diatoms and mycorrhizas.

Step 2. Week 1-2 

When the little seedling emerges from the ground and begins to absorb the first rays of sunlight outdoors, you must ensure that it does not suffer from light stress. Therefore, we recommend using some type of filters such as a mesh or similar so that the sun’s rays do not affect the plant in its development due to light stress.

Roots Marijuana Plant

It is important to point out that in the first and second week, the most optimal thing is to irrigate the seedling only with water and the minimum dose of rooting agent to avoid over fertilization or a possible disease due to nutrition. 

Step 3. Week 3-4

Due to the above, the substrate of the autoflowering strain should be well enhanced, rich in nutrients, and have fungi to help the development of the roots during the first phase of growth. All of this enhances the optimal progress of the plant.

Then, in week 3-4, the plant is already stronger, so you can start watering with the fertilizers and stimulants you want, keeping in mind that it is important to use the minimum or average doses in relation to the amounts recommended by each brand of nutrients. We say that because balanced nutrition for each plant will depend on the genetics you have in your garden and also by using minimum or medium doses to avoid over fertilization problems or your plants suffering from a disease due to excess fertilizers.

Step 4. Week 4-5

In this period, you will see the first pistils appear and the flowers begin to form. It is important to keep temperatures and humidity controlled, but since you grow outdoors, this becomes impossible.


Buds affect by botrytis

However, you can apply some tricks to help you keep your outdoor crop in good shape. For example, water the plants in the morning to avoid faster evaporation of the water when it is hot. Also, you can use a protective stimulant for the roots and another to avoid stress and thus you will take care of the autoflowering plants during the hours that the temperatures are higher and the lowest humidity. Also, you can apply some supplements that are rich in silica to make your plants more resistant.

Step 5. Week 7

When you reach week 7 and you are growing outdoors in the summer season, it may be possible that the plants are affected by mold or mites. For this reason, it is good that you maintain preventive control over your crop, constantly checking it to avoid the buds being damaged by diseases. If you want to carry out biological control, you can use ladybugs because they are your great allies to eliminate different types of mites and insects. 

If we talk about mold or botrytis, you can preventively apply some to the substrate and it will help you avoid having these types of problems. The “bacillus subtilis strain QST 713” fungus that prevents the spread of botrytis spores is very effective against powdery mildew. The “bacillus pumilus strain QST 2808” is a non-pathogenic fungus that takes care of the proliferation and spread of botrytis spores and protects your plant for up to 14 days from its application to the soil or culture substrate.

Step 6. Week 8-9

It is time to flush the plants to remove excess fertilizers or salts from the substrate where the plant is grown. For this, it is good to stop applying fertilizers and irrigate only with water to allow the plant to feed in the last weeks with the nutrient reserves that are scattered throughout the substrate.

In the market, there are different flushes indicated for this task and there are also different root washing techniques that can be used to obtain buds with a rich flavor and smoke. Cannabis plant washings can be done 2 or a maximum of 3 times about 2 or 3 weeks before harvesting the plant. You can apply defoliation in the lower and middle part of the plant to eliminate those leaves that are withered, dry, or have a yellow color. This helps the upper tips of the plant finish flowering in a better way.

Step 9. Week 10-11

In general, autoflowering plants have a complete life cycle that goes from 8 to 10 weeks. Therefore, in this tutorial, we will tell you that it may take an extra week. At this time, the plants are already ready to be harvested and it is important to see the signs on the leaves such as the color. You should also analyze the color of the pistils and especially of the trichomes which tend to turn brown.

The trichomes are great indicators that the marijuana plant is ready to be harvested because they go from a transparent white color to an intense brown. That is when many gardeners prefer to harvest. After this comes the trimming of the cannabis, drying, and curing.

You already know how to start cultivating your autoflowering cannabis strains in the best way. Now you only have to start sowing to expect a great harvest in a few weeks. See you on the next blog and remember that practice makes perfect! You can continue learning with our blog and practicing in your garden to harvest the most incredible plants you have ever had.

Strains featured in this article:

Mike Wilson

Mike Wilson is a passionate cannabis cultivator with over a decade of experience in the California cannabis industry. Born and raised in the heart of the West Coast, Mike has dedicated his life to honing his skills as a cultivator, becoming a true master of the plant. His love for cannabis and profound knowledge of its cultivation have led him to explore every facet of this captivating plant, from classic strains to the latest trends in cultivation and advanced techniques.

With a unique perspective on cannabis culture and a focus on sustainability and quality, Mike generously shares his valuable tips and tricks on this platform. Through his posts, he will guide you on the exciting journey of cannabis cultivation, providing expert insights and practical experiences to help you achieve success in your own cultivation endeavors. Join Mike on his journey through the world of cannabis and discover how to cultivate responsibly and achieve exceptional harvests. Become part of his community and unlock the secrets of a true cannabis master!

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