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Soil Mix Made to Grow Great Autoflowers

Last Updated: March 13, 2023By Joshua Mezher

Soil and Cannabis

Everyone is getting on board the growing your own weed train, and it’s a good thing. Learning to grow your own cannabis is a valuable skill for any cannabis lover. Now, with so many states legalizing the home growing of marijuana, more people are discovering their green thumbs. 

One of the most common mistakes among newer growers, whether they choose to grow outdoors or have a cheap indoor grow setup, is growing their cannabis in the wrong soil. A lot of times, this comes from using the typical soil that you can find at a hardware store. For instance, MiracleGro is terrible for cannabis plants and will more than likely end up killing your crop. The fact is, cannabis is only as good as the medium it was grown in. If you want to grow top-shelf cannabis, you need to use top-shelf soil. 

The Importance of Good Soil for Autoflowers

One of the biggest mistakes a novice grower can make is growing their cannabis in the wrong type of soil. Even experienced growers can make this mistake. If you’ve been growing vegetables for years, you already know how to grow plants, right?  You are correct, of course, but marijuana, although a hardy plant, still has specific needs that cannot be met by many of the commercial soils that you’ll find at the local hardware store. 

It is no surprise that many experienced growers that are new to growing marijuana may be tempted to use MiracleGro. It is a very well-known brand of plant food and soil, and it’s used in gardens throughout the country. It has made our flowers bloom brighter and our tomatoes juicier, does logic not dictate that we should use it on weed too? As it turns out, using MiracleGro is perhaps the worst thing that you can do as a cannabis grower. The main issue with this soil is that it only contains one type of formula. As you know, cannabis goes through several different stages, requiring a variety of nutrient combinations. As a result, your plants become nutrient deficient, get sick, and then die. While autoflowers can handle things that would kill photoperiod plants, even they cannot handle the amount of nitrogen contained in MiracleGro soil. 

So now that it is clear why Miracle Grow is a bad idea let’s talk about what you could gain by using the correct soil. First of all, you can expect healthier plants. When you use the best possible soil, your plants are less susceptible to damage from things such as nutrient deficiencies or nutrient burn. You will also be able to increase your yields, which is very beneficial to autoflower growers since autoflowers tend to have lower yields than photoperiod seeds.

We know what soil not to use, but what type of soil should you use? The best mediums for growing weed come in many different forms, but the best ones all include a combination of compost, peat moss, perlite, and vermiculite. You can buy these specific soils, or you can make your own. We’ll get into how to make your own later. 

A quick note on coco vs soil autoflower medium

As a newer grower, you might be tempted to try growing in coco coir. It’s not a bad idea, as coco coir is a fantastic medium for growing good quality dank buds. However, it is not recommended for newbies. Unlike premixed soil, coco coir requires precise and complicated nutrient formulas to give your plant the best environment. If this is your first rodeo, as they say, you might want to consider skipping the coco and opting for the soil.

Related Article: How to Grow Autoflowering Cannabis

Do Autoflowers Do Well in a Super Soil?

Autoflowers are incredibly hardy plants, and as such, they can handle many different types of soils. But if you already own less than optimal soil, you could have better results by using a super soil autoflower concentrate. Super soil is simply a soil that is made specifically for growing cannabis. The concentrate contains all of the nutrients you will need during your plants’ life; you’ll simply mix it with standard soil to create the optimal growing medium for your plants. 

Many new cannabis growers may wonder why they should be concerned about a specific soil for autoflowering cannabis plants if the plants are already quite hardy. In other words, why should you go with soil specifically for cannabis? Think about the difference between eating locally sourced, organically grown fruits and vegetables versus eating the kind you find in the produce aisle of your grocery store. Which taste do you prefer? Think again about cannabis that you buy in the dispensary that was organically grown in the best possible medium, versus the ditch weed we used to smoke back in the late nineties and early aughts. It’s not that difficult of an answer if you think about it. Do you want your cannabis to resemble a five-star gourmet meal at a high-class French restaurant, or do you want McDonald’s? I think the world has enough McDonald’s, don’t you?

On that subject, it is appropriate to mention synthetic nutrients, that is to say, do not use them! While you might be tempted to play god, this is one of those cases where you should just let mother nature do what she does best and just let it grow. You don’t want synthetic ingredients, dyes, or any of that crap in your food, so why would you want them in your weed? Autoflowers are tough, yes, but that does not mean that they prefer the cheap stuff. They want the super soil.

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How to Germinate Autoflower Seeds in Soil

Contrary to popular belief, it is not advisable to germinate your autoflower seeds in soil. Many common garden plants can germinate in soil with no issues; however, cannabis is not your typical garden plant, not even autoflowers. As such, cannabis seeds require more care and attention than other seeds. 

That’s why we recommend germinating your seeds in a jiffy pellet after soaking in distilled water for up to 24 hours, or in a damp paper towel (damp, not sopping wet!), though some seeds may take more time to sprout. Once your seeds have properly germinated, or “popped” to use the grower’s vernacular, you will need to fill some small pots with your soil mix. Bury your seed a half-centimeter or centimeter into the soil with the taproot (the little tail your seed develops during germination) facing downwards. Cover your seedling in a small amount of soil, but not too much! 

Ideally, you should leave your seedling in the soil under a grow light until it emerges from the soil, and you can transplant it to its final growing place. If you don’t use a grow light, be sure to provide plenty of light. Make sure that your seedling does not get too cold or it won’t grow! It will usually take around 4-5 days for your plant to grow large enough for it to be safely transplanted.  Make sure not to let your plant develop too much, or you will not be able to transplant it without causing damage. Let me repeat, it is vitally important that you not leave your seedling in the temporary pot for more than 6 days, or you will not be able to transplant them safely! Sorry to sound like a broken record, but this is a mistake that many new growers make. Ignore this advice, and you may be in the same boat. 

Related Article: How to Germinate Your Seeds

How Much Soil Does an Autoflower Need?

Autoflowers are smaller plants than photoperiod plants, so they will not need as much soil, but it largely depends on how many you are planning on growing. 

If you are wanting something like a mini desktop plant setup, where you are planning on growing only an ounce or less, then you will not need much, only about a half-gallon pot of soil. This quantity is excellent for people who are just starting out, perhaps only wanting to grow 1-2 plants for personal use. If you’re brand new to growing and don’t have a lot of time or money, or don’t really know if you’re going to like growing your own marijuana, then this is the size for you. 

If you are planning on growing a bit more for your personal use, maybe less than five ounces, your best bet will be to go with a 2-gallon pot, which can yield you up to 112 grams or four ounces of high-quality herbs. Two-gallon pots are great if you have a little more room in your grow space and a bit of money to spare. Five-gallon pots are the standard that most growers agree is right for them. 

Five-gallon pots, while too large to fit on your desktop or windowsill, still fit comfortably on your balcony or patio, in your grow tent, or in your outdoor garden or greenhouse. A five-gallon pot will easily yield up to 8 ounces, which should more than cover the expenses of your growing equipment, plus save you plenty of trips to the dispensary. 

Of course, there are other sizes. For example, photoperiod growers love 35-gallon pots, which will net you over a pound of marijuana. However, it is not a good idea to grow autoflowers in a 35-gallon container, as their life cycle is too short to warrant it.

Feeding your Autoflowering Plants

Now, let’s talk about how to feed cannabis plants in soil. Feeding is one of the most important aspects of growing any marijuana plant, but the process is a lot easier with autoflowers. You might think that they need a lot of fertilizer nutrients like photoperiod cannabis plants, but this is not the case. Autoflowers need less food than photoperiods, and because of this, it is very easy for a new cannabis grower to overfeed their plants, which can lead to disaster. 

The most important thing to remember is to keep an eye on your nitrogen levels as too much nitrogen can be devastating to small plants, such as autoflowers. Yet another reason why you should never ever EVER use MiracleGro, which is filled with nitrogen. Your best bet is soil that is designed for autoflowering cannabis and a guide, such as the Advanced Nutrients feeding schedule autoflower edition. Keep in mind, that calculator is intended for specific nutrients, which may not be ideal for autoflowering plants. However, it is a useful guide for showing how precise you should be when feeding cannabis plants. 

There are other considerations to keep in mind, outside of nutrients. Experts recommend that you add mycorrhizal fungi to your soil. It’s important to note that these are not nutrients. They are simply organic lifeforms that break down organic matter in your soil and transport it to your plant’s root system. Though not required for your plant’s survival, it is a good idea to introduce these into your soil. 

Another critical thing to keep in mind is the pH of your soil. The pH scale ranges from 1-14 with 1-6 indicating acidity, 7 being neutral, and 8-14 being alkaline. Cannabis plants like things on the more acidic side, so ideally, your pH should be anywhere from 6.2-6.5. Always test your plant’s pH regularly and make adjustments as needed. If your pH is too low, meaning your soil is too acidic, you can always add dolomite to it to make it a little more alkaline. If your soil pH is too high, meaning it’s too alkaline, add some pine needles to set it right where it needs to be. pH testing strips can be purchased in most stores, so be sure to pick some up if you’re creating your own soil. 

Popular Soils for Autoflowering Cannabis Seeds

There are plenty of soils that are suitable for growing autoflowers. Let’s take a look at some of the pros and cons of each. A Nature’s Living Soil autoflower review on Amazon.com shows that the soil is generally great for their plants, but others have said that they couldn’t tell if it made a difference in their plants whatsoever. One reviewer even claimed that their plants were actually nutrient deficient from it. One of the most popular potting soils used for growing marijuana is Fox Farm Ocean Forest soil and Happy Farm Organic potting soil. Looking specifically at Fox Farm soil autoflower, there were many positive reviews; however, there were also quite a few that said it was quite a bit more than what they were wanting to spend. Overall, it’s a fantastic soil, but is the price worth it? 

Many of the soils that you find online will say the same thing. Unless you want to spend a lot of money, you might end up with something that doesn’t do enough or does too much, potentially harming your plants. That’s why some growers choose to make their own soil. So, how easy is that, and does it involve math? 

How to make the best Autoflowering Soil

Knowing how to make your own soil is a useful skill, even if you never end up needing to do so. At a minimum, it helps you recognize what to look for when you purchase soil. When you know what is supposed to be in your soil, you can choose which ingredients you want, depending on your tastes. Add what you want and leave out what you don’t. The best soils for autoflowers can have up to 17 ingredients in the substrate. 

As a general guide, the following formula is recommended. Start with 3 parts peat moss, 3 parts compost, 2 parts perlite, and 1 part vermiculite. You’ll want to use the following process. First, start by spreading out the soil. Then, add the first ingredient and mix well. Repeat this step for every ingredient. Once you are done, you should wrap the mixture with a tarp, then allow it to sit for 24 hours. This process is called “cooking the soil.” It helps ensure your soil is well blended and ready to support your plant. 

When the time comes to plant, fill your container one-third full of your soil mix, then fill the rest with topsoil. Doing so will encourage your plant to grow downward into the soil, using nutrients as needed. This step prevents your plant from taking in too many nutrients at once. You don’t want this because it could damage your plants. 

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Soil does not have to be complicated

Using the right soil is a critical step for growing the best marijuana plants – even when you are talking about autoflowers. Yes, these are the easiest types of marijuana plants to grow, but you could still mess it up, and chances are, your soil is where you will make a mistake. Instead of wasting your precious time searching for the best soil (or making your own), and possibly also losing your plants in the process, why not just try the Superb Soil from aPotforPot.com? Not only is it specifically designed for autoflowering cannabis plants, but it also has everything that your plants crave to keep them healthy and happy.

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