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Best Soil for Autoflowers: A Complete Guide

Cultivating a thriving crop requires more than just planting a few seeds in the right spot. You should look at the best soil for autoflowers to ensure that you’re providing the perfect conditions for optimal yields.

Autoflowers have developed a reputation for their simple and fast growing process—and rightfully so! Within just 12 weeks, you’ll enjoy impressive harvests—especially if grown in a nutritious environment. 

An optimized grow space, fantastic temperature and humidity control and the best lighting system all contribute to the weed quality. With premium seeds and the best soil, you’ll have the makings of a great grow!

Join us as we discuss the best options of soil for autoflower, why it’s so important, and how to determine which is best. Let’s take an in-depth look at different soil types. We'll even explain how to make your mix of autoflower soil. 

best soil for autoflowers

Autoflower soil: why is it so important to choose the best option?

The decision on which type of soil for autoflower to use is a crucial component. This critical decision, if made wrong, could make or break your crop's success.

So what’s the difference between using the best potting soil and autoflower soil? Allow us to explain.

Different types of additives make it particularly difficult to decide on the best soil option. Understanding the role each one plays along with growth and drainage has an impact on the yield of your plants.

An autoflower soil guide offers important facts and information regarding the different soil types. 

While autoflowers produce smaller yields than photoperiod seeds, using the best soil helps your plant reach its full potential.

Once you’ve chosen the strain you’d like to plant; select your preferred medium and the best soil for your autoflowers.

It’s best to ascertain whether your chosen seeds are better suited for indoor or outdoor growing and the climate conditions in your region. 

When selecting the best soil type, are a few things to note: pH balances, nutrients, characteristics, and even environmental friendliness.

Choosing the best soil for autoflower determines the growth process and yield of your harvest.

Consider using the best suitable drainage soil if you plan on planting indoor autoflowers, to prevent root rot. An important fact to note, the more oxygenated the substrate, the faster the plant's metabolic growth process will be.

Using the best soil for autoflowers makes the plant less susceptible to damage caused by nutrient deficiency or root burns. If you choose a soil type with slow-release nutrition, you must look for the best-suited soil medium.

best soil for autoflowers

Soil for autoflower: what are the main characteristics of healthy soil?

How do you identify the characteristics of the best autoflower soil? As we answer this question, let’s look at natural soil, which you can use for planting your autoflower. You’ll find this soil in four variants, namely:

  • Clay
  • Loamy
  • Sandy 
  • Silty

Clay: A heavy medium, fine texture, and extremely rich in nutrients and minerals. It has high pH levels but poor drainage.

Loamy: This one is the best of the four, a combination of silt, clay, sand, and organic compounds. It offers good water retention, and drainage, and has high oxygen levels and many nutrients.

Sandy: Is coarse, with good drainage but poor water retention, high oxygen levels, and low pH.

Silty: Being a medium-coarse soil type, it contains organic particles and is rich in minerals, with a great balance between water retention and drainage.

Aerated autoflower soil is a fantastic oxygenated medium that holds moisture without allowing drenching the roots.

You might not have heard of coco fiber or coco coir before, so let’s look into its function for your autoflower. This soil type promotes drainage and aeration but lacks the required nutrients.

Organic soils have more nutritional properties if you look at environmentally friendly soil for planting your autoflowers.

Another characteristic to note when buying autoflower soil is that it has the optimal pH range of at least 6.2–6.5.

Even the best autoflower soil with insufficient nutrients could stunt your harvest's development and yield it isn’t well-balanced.

Best store-bought soil for autoflowers

It’s a quick and easy option to buy bags of pre-mixed soil for autoflowers online or at a nursery store. Keep in mind that the quality may not be the best as they often contain additives like:

  • Bat guano
  • Worm castings
  • Dried blood
  • Fish
  • Pulverized bone
  • Calcium
  • Magnesium-rich minerals like dolomite

When faced with various options, selecting the best soil for autoflowers could be daunting, so we’ve compiled a list of our top picks.

best soil for autoflowers

Organic soil mix

When looking at the organic soil composition, it's one of the healthier options to consider when planting your autoflowers.

Organic autoflower soil mix consists of 70–80% organic soil, 15% perlite, and 15% cocoa fiber. The function of perlite is to provide adequate water retention. 

Ensure that the organic soil contents consist of materials in a permanent decomposition state. In conjunction with microorganisms, they convert nutrients to the roots of the autoflower.

For optimized growth, organic living soil for autoflower cannabis it's enriched with a microbiome, which is beneficial for healthy plant growth.

Super soil

Super soil is a quick, easy, and a no-mess way of planting straight from a bag, making it a top choice for all experience levels. 

Super soil for cannabis contains organic components like microorganisms and creates an ecosystem, providing everything it needs to grow. 

So why is super soil the best for autoflowers? It’s the most biologically diverse soil, with no need for fertilizers.

Farm soil

Farm soil is another healthy option great for growing autoflowers outdoors due to its raw organic compost mixture. This mix contains crab meal, granite dust, fish emulsion, peat moss, shrimp meal, and oyster shells.

It's light and aerated, perfect for what your autoflowers need for the roots to grow in a healthy state. Ensure that your store-bought soil has the right pH balance to avoid killing the microorganisms in the soil.

How to make your own autoflower soil mix 

Now that you’ve chosen your autoflower seeds and have your grow spot, why not try making a soil mix?

Gather up your ingredients and get ready to get your hands dirty by making an autoflower soil mix at home! Making your soil medium requires an organic foundation, the correct amount of minerals, nutrients, aerated additives, and plant fertilizer. 

With a few simple ingredients, you’ll have a quick, easy, and cost-effective self-made autoflower soil mix. The ingredients needed are:

  • ⅓ part sphagnum peat moss
  • ⅓ part perlite or pumice or coco fiber that allows for aeration is vitally important as it allows moisture and air to allow the roots to grow freely.
  • ⅓ part high-quality compost combined with worm casting, and this is optional.

Simply mix all ingredients in a container big enough, preferably with a lid, and allow to rest for up to two weeks. During the resting period, the colonies increase as the microbes begin to break down the organic matter.

You can tweak your mixture by adding germ genie (kelp), which contains soluble potassium, amino acids, auxins, cytokinins, and vitamins.

If you find the pH is too high or low, check the nutrients you're adding; remember that some additives are sterile and neutral.

When combining soil additives into your best soil medium for autoflowers Always take your plant’s specific needs into consideration.

Coco fiber is suitable for dry environments and improves soil quality. It also has high water retention and aids against soil compaction.

Biochar is also a suitable soil medium for dry climates in organic soil mixes. Its balance between water retention and drainage and faster nutrient decomposition leads to healthier autoflower roots. 

Adding perlite to your autoflower soil also aerates it, making it conducive to humid conditions, and preventing the soil from becoming soggy.

Vermiculite helps keep the autoflower soil mix moist in dry environments and sustains the nutritional properties in the soil mix. 


If you’ve reached this far, we hope to have answered any questions you may have. In case we haven’t, here are a few commonly asked questions to clear up any uncertainties you may have.

How do you prepare soil for autoflowering?

The soil you’re going to use to plant your autoflower needs to be prepared by mixing all ingredients according to specifications and ratios. Once the mixture has rested after the two-week period it’s ready for planting. Remember that your plant still goes through different growing stages, thus having specific nutritional requirements

Is living soil good for autoflowering?

Living soil is highly recommended as being good for autoflowers, provided you add compost, feeding it with the correct amount of nutrients required.

The use of living soil optimizes growth for your autoflower due to the diverse microbiome it contains.

Can you plant autoflowers directly in soil?

You can but it’s not advised as chances of success vary. Before planting your seeds, germinate your seeds using the paper towel method as recommended in our germination guide.

It’s best to use a breathable container to allow autoflower roots oxygenation, like an airpot or a fabric container. Your planter then needs a drainage base with pebbles, followed by worm castings, and topped with your chosen soil medium.

Can you grow autoflowers in super soil?

Super soil is made to grow autoflowers, making it the ideal soil mixture to use as it contains all the nutrients required. By adding standard soil, you increase the growth and yield of your autoflower crops.

With 100% organic elements containing microorganisms it creates an ecosystem as we find in nature.  

Get the right soil for your seeds

Once you have your seeds chosen, the next step is to find a suitable autoflower soil for optimal yields from your plant.

When purchasing or making autoflower soil, remember to check if it’s aerated, retains water well, has suitable pH levels, and sufficient nutrients.

Whether a shop-bought soil mix, self mix, or pre-mix, you can re-use it if you have a well-balanced selection for the best autoflower soil.

Be sure to check out our range of fertilizers and nutrients to help your cannabis crops thrive. So what are you waiting for? Go ahead and get your hands dirty!

About the author: Derek LaRose

Also known as Kronic from The Cannabis Kronicles, Derek LaRose is a young ambitious cultivator and a staple educator for indoor cultivation.

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