Best Soil For Autoflowers

Autoflowers are a type of cannabis plant that automatically transitions from the vegetative state to the flowering stage with age, rather than in response to light conditions. This characteristic comes from the Cannabis ruderalis subspecies, which imbues autoflowering plants with their swift growth cycle and resilient nature.

Living soil and Hemp Plants

Good soil for autoflowers maintains a fine balance – it should be nutrient-rich enough to support their rapid growth, yet not so overloaded to cause nutrient burn. The ideal soil is also loose and airy, promoting strong root development and efficient water drainage. Mixes specifically crafted for autoflowers or light and fluffy potting soil blends are generally best suited for these versatile plants.

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What Makes the Best Potting Soil for Autos


The best potting soil for autoflowering cannabis is one that caters to their preference for a growing environment that is light and non-restrictive for roots. The make-up of such soil consists of a few key components:

Peat Moss: This ingredient ensures the soil retains moisture while remaining light and breathable. It effectively anchors the roots, providing a stable environment for your plants to thrive.

Compost: A well-decomposed compost enriches the soil with a variety of essential nutrients without being too heavy. It also introduces beneficial microorganisms that aid in root health and nutrient uptake.

Perlite: Perlite’s presence in the soil mix enhances drainage and helps prevent compaction. It creates air pockets within the soil, which is vital for the development of a healthy root system.

Vermiculite: While it also improves aeration, vermiculite’s main role in the mix is to hold onto water and nutrients, releasing them slowly to the plant roots as needed.

To create the best potting soil for autoflowers, combine these materials in a specific blend — generally, a mix of three parts peat moss to three parts compost, with two parts perlite and one part vermiculite is recommended. This blend encourages strong root systems while maintaining a suitable balance of moisture and aeration.

Autoflowers, due to their genetics, tend not to require a high amount of additional nutrients, particularly in the seedling phase. For these reasons, it’s imperative to avoid soils that are very rich or heavily fertilized, as these can overwhelm the plants and lead to nutrient burn.

For growers looking to strike the perfect balance with their potting soil for autos, this blend provides nourishment while supporting vital root growth, leading to healthy and vigorous autoflowering cannabis plants.

cannabis soil mix before
cannabis soil mix after

Popular Brands with Ready-to-go Soil for Autoflowers

For those who prefer to skip the mixing and get straight to planting, there are several reputable brands offering high-quality soils that are ideal for autoflowering cannabis. Here are some popular options that you can find on the market:

FoxFarm Happy Frog Potting Soil: FoxFarm Happy Frog Potting Soil is less nutrient-dense than FoxFarm Ocean Forest, making it ideal for autoflowering cannabis which can be sensitive to strong nutrient concentrations. It’s well-aerated with a mix that allows for healthy root growth and proper drainage. The inclusion of mycorrhizal fungi supports nutrient uptake without overwhelming your plants. Happy Frog provides a solid foundation, allowing your autoflowers to flourish gently from sprout to harvest.

Fox Farms Happy Frog

Roots Organics Formula 707: Roots Organics has a formula specifically prepared to nurture cannabis plants. With ample organic matter for nutrient retention and with added perlite for extra drainage, it forms an excellent environment for the root systems of autoflowering cannabis.

Black Gold Natural & Organic Potting Soil: This readily available mix is another good option, providing a well-draining, nutrient-rich soil. It’s bolstered with pumice and organic fertilizer, but isn’t too nutrient-dense for delicate autoflowers.

Biobizz Light-Mix: Perfect for autoflower growers looking for a substrate that encourages fast root development. Light-Mix contains a light concentration of nutrients ensuring young plants are not overwhelmed.

ProMix HP: ProMix HP is an excellent substrate for autoflowering cannabis due to its high porosity which promotes strong root development and optimal gas exchange. Its lightweight, sphagnum peat-based composition ensures consistent moisture retention while preventing overwatering. This makes it particularly suitable for the fast-paced life cycle of autoflowers, which thrive in environments where their roots can expand freely and access air and water efficiently. ProMix HP serves as a reliable base for your autoflower soil mix, providing a clean and controllable foundation for growth. It can be improved with soil amendments like Reefertilizer Start.

Pro Mix HP

When using ready-to-go soils, it’s important to remember that autoflowers have different nutrient needs compared to regular photoperiod strains, especially during the early stages of growth. Therefore, it’s crucial to monitor your plants for signs of nutrient burn or deficiency and adjust your watering and feeding schedule accordingly.

By choosing one of these ready-made soil options, growers can provide their autoflowers with a solid foundation for healthy growth and robust yields.

Reefertilizer Start: Enhancing Autoflower Soil

Reefertilizer Start is a robust organic soil enhancer, specifically formulated to bolster autoflower cannabis growth. This compost blend contains mycorrhizae and brown sea kelp, pivotal for developing a strong root system and improving soil vitality. When mixed into the soil of starter pots or used as a top dressing, it helps seedlings accelerate their growth by enhancing nutrient and water absorption capabilities. With Reefertilizer Start, growers provide their autoflowers with the nutritional support needed for a vigorous life cycle.

Reefertilizer Start being used on cannabis seedlings

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