Germination guide for autoflowering seeds

Germinating autoflower seeds is an important first step on your grow journey. Keeping sterile conditions and controlling the environment will propel your plants toward success. Autoflower seeds can be germinated using common techniques; what happens after germination makes the autoflower process slightly different. By giving your seedling a healthy, stress-free start, you establish a strong base for high yields.

Should you germinate autoflowering seeds differently?

When people think of temperature, they usually think of the air around them. When germinating autoflower seeds, growers must also be conscious of the soil temperature. The best way to germinate autoflower weed seeds is in an air temperature of 21°C – 28°C (70°F – 82°F). The ideal soil temperature would be between 20°C – 30°C (68°F – 86°F). You can achieve this with controllable heat mats, but they aren’t necessary on every occasion.

The main difference for growers germinating autoflower seeds compared to photoperiod seeds is that autoflowers should be placed into the final container once sprouted. Photoperiod seeds are commonly transplanted into larger pots as the roots reach the bottom of the container. Some hypothesize that with autoflower strains, this action initiates flowering. By using the larger final pot right away, autoflower plants get maximum vegetative time.

Find a step-by-step germination guide for your autoflowering seeds in Robert’s Grow Bible below!

Should I germinate autoflower seeds in the dark?

All seedlings require light. Actively germinating auto seeds, however, prefer the dark. Not all seeds from the plant kingdom need darkness; some prefer light, but autoflower germination is best under dark conditions. Creating a dark environment by using something as simple as a cupboard drawer will do.

You need autoflower seeds before you can germinate them! ILGM has some of the most popular and easy-to-grow autoflowering seeds available. Click below to see our collection!

bergman holding autoflower plant

Buy Autoflower Seeds

  • For new and experienced growers
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How to germinate autoflowering seeds

Equipment and supplies

Growers don’t need to break the bank by buying special equipment to germinate autoflowers. The two most common methods of germinating autoflower seeds involve a glass of water and the other, a wet paper towel. The space required to germinate auto seeds is also minimal. Many times a dresser drawer or a spot on the shelf in a dark closet will do fine. Direct sowing into the soil is also a popular option.

If growers want to invest in specialized gear, some options can assist the germination process. Cloning and seedling kits, consisting of a tray and clear dome, are popular. Water in the base of the tray condensates on the dome, which helps maintain humidity levels. Popular germination media to place inside those domes include rock wool cubes, peat pellets, and seed plugs.

Preparing marijuana seed growing medium

Preparing medium

Preparations will vary depending on your final medium, whether it be coco, soil, living soil, or hydroponics. The latter is unique in that there isn’t a true medium the roots live in. Oftentimes, roots grow around small clay-expanded balls in net pots. Be sure to wash these balls before use and check their runoff water’s pH before placing your germinated seedling in the net pots. 

The main consideration with other mediums is to get them pre-moistened. Roots, especially new roots, need an even balance of water and oxygen to succeed. Coco has excellent aeration and can be given more water than traditional soil. When germinating autoflower seeds in soil, add a slight amount of water around the buried seed, not on the outer walls of the container. Living soil needs to stay wet at all times to support the microbial colonies, but be careful not to drown the new seedling.

PH meter to check water for growing marijuana seeds

Tips before germinating auto seeds

Keep your germination area clean

Establish where you wish to germinate your autoflower seeds and confirm that the environment meets the required temperature, humidity, and darkness. Keep a clean environment. Prevent dirt and dead leaves from accumulating in tent corners. Don’t have small pools of spilled water on the floor. Reduce the chance of pathogens entering the garden and killing your fresh seedlings. 

Don’t touch the first root of your autoflower seedling

Don’t touch the radicle, which is the first part of the seedling to emerge from the shell. People often refer to it as the “little white tail.” The radicle is fragile. Do not touch it with your hands. Use tweezers to plant the germinated autoflower seeds into your medium. Clearly label your seedlings. Have tags and Sharpie next to you as you move the germinated auto seeds into your medium. Immediately label each container with the strain name.

Don’t touch that first root (radicle) with your hands. It’s fragile!

Do you have to soak autoflower seeds?

Autoflower seeds, just like photoperiod seeds, have a hard outer shell. Soaking the seeds in water for 12-24 hours before germination can soften the shell, making it more permeable for water to enter. Depending on your germination method, this step may not be needed. Older seeds tend to have thicker shells; soaking older seeds first often helps with germination rates.

The pH of the water you use to soak or germinate seeds is important. It would be bad news if the sensitive radicle emerged into a hostile environment. A gardener does everything to make the plant comfortable in its surroundings. Autoflower germination is no different. Having the right pH can have an impact on your success.

Soaking cannabis seeds in a glass of water

How long does it take for an autoflower seed to germinate?

The time it takes an autoflower weed seed to germinate in the ideal environment will depend upon a few things. Age is a large determining factor. Older seeds generally take a few more days to germinate than fresh autoflower seeds. This is due to reduced vigor over time, which occurs naturally but can be accelerated by poor seed storage.

Vigorous autoflower seeds will typically crack and expose the radicle within 36-48 hours when using the soak or paper towel method. If placing your autoflower seeds directly into the soil or into a rock wool cube or seed plug, 5-7 days is common. In the latter method, the seedling is more established than the tiny tail we might see in earlier-mentioned methods. All seeds should emerge with their cotyledon* first, which is where they get the energy to grow until newly formed leaves can photosynthesize.

* The cotyledon is essentially the “embryo” of a plant seed. It’s packed with nutrients for the first days of a developing seedling. Later, once the seed has fully sprouted, it will grow into the seedling’s first leaves.

How many weeks/days is an autoflower seedling stage?

Once you see the cotyledon above the surface, the autoflower seedling stage has begun. This stage lasts roughly 10-14 days as the root system establishes. Usually, the plant transitions into the vegetative stage when the autoflower seedling produces its first five-fingered set of leaves.

Autoflower seedling sprouting

How often should I water autoflower seedlings?

It is better to give soil-based autoflower seedlings regular small amounts of water than a lot at once. Do not drown the small and fragile roots. Your autoflower will drink more as the root zone develops.

The best methods to sprout autoflowering seeds

Method 1: Paper towel

Time needed: 2 days.

  1. Wet and cut your paper towel in half.

    Wet a paper towel and ring out roughly 80% of the water.

  2. Place seeds inside the paper towel.

    Fold the paper towel in half and ensure the seeds are in full contact with the paper towel.

  3. Place the paper towel in an open plastic bag to retain moisture.

    Place this in a warm, dark location. Check daily to ensure the paper towel stays moist.

  4. Transfer radicle to your grow medium.

    Once the radicle emerges 0.7 – 1.3 cm (1/4” – 1/2”) from the autoflower seed, place it into your medium with the tip pointing down.

Method 2: Soaking overnight water

  • Step 1 – Pour pH’d water into a glass. It does not need to be deep, but enough for the autoflower seed to float and sink to be fully submerged.
  • Step 2 – Add your seeds to the water. Wait until the radicle emerges. 
  • Step 3 – Once the radicle emerges 0.7 – 1.3 cm (1/4” – 1/2”) from the autoflower seed, place it into your medium with the tip pointing down.
soaking seeds in a glass of water

Method 3: Using a germination chamber

There are many kinds of germination chambers. The principle behind them is that they are an enclosed area where temperature and humidity can be set and maintained. In the commercial environment where 1,000s of seeds are germinated simultaneously, these devices are a time and labor saver. 

Method 4: Rock wool cubes and peat pellets

The process of germinating autoflower seeds in rock wool or germinating autoflower seeds in peat pellets is very similar. In both instances, you place your autoflower seed into a predrilled hole and then moisten the media. The hole firmly holds the autoflower seed, giving it the contact, moisture, and darkness it needs to germinate.

Cannabis seed sprouting

Method 5: Planting directly in the soil

Many growers directly germinate autoflowers seeds in the soil. Place the autoflower seed about 0.7 cm under the soil with the pointed side down to do this. Provide the soil in the immediate area with a small amount of water. Some people ask, how long does it take for autoflower seeds to germinate in soil? If the temperature and moisture levels are on-point, the seedling should emerge within 5-7 days.

Germinating autoflower seeds can use the same processes as germinating photoperiod seeds. A wet paper towel, a glass of pH’d water, rock wool, peat pellets, or direct sow can all be effective. The temperature and humidity must be in the desired range in each scenario.

Want to try out some of the best autoflower seeds? Check out our mix pack for your next grow!

Auto Flower Mix Pack

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But what if your autoflower seeds are not germinating?

Evaluate your process, and figure out the problem. Do you want a guaranteed 100% success rate? Order your autoflower seeds from ILGM. We stand behind our products and the education we offer by guaranteeing germination on all our ILGM seeds. What is your favorite method for germinating autoflower seeds? Do you have more than one way? Share it in the comments, and also let us know your favorite ILGM autoflower strain. Stay groovy!


Avatar for Chad Westport

Mr Chad Westport

Independent Marijuana Breeder

Chad Westport is a lifelong grower and cannabis educator. He specializes in controlled environment agriculture and has a degr ... See profile

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