10 Best Outdoor Cannabis Fertilizer 2025 in the United States

The FoxFarm Fertilizer Soil Trio Liquid Nutrient kit includes three products: Grow Big, Big Bloom, and Tiger Bloom, each designed to support different stages of plant growth. This makes it a versatile option for outdoor cannabis growers. One of its strengths is its organic formulation, particularly Big Bloom, which is both OMRI Listed and registered as a CDFA Organic Input Material. This can be beneficial for those looking to grow organically.

The liquid form ensures easy application and quick absorption by plants, which is useful for seeing faster results. Additionally, the included Twin Canaries Conversion Chart helps users mix the nutrients accurately, which can be a great help for beginners. The pack's phosphorus-rich Tiger Bloom is particularly good for encouraging flower and bud development, which is crucial for cannabis plants.

This product is best suited for those who want an easy-to-use, organic option with a focus on both vegetative and flowering stages, although it may require additional slow-release nutrients for long-term feeding.

The Farmer’s Secret Fruit & Bloom Booster Fertilizer is designed to enhance flowering and yield across various plant types, including cannabis, making it a versatile option for outdoor gardeners. Its super concentrated formula means you only need a small amount (1 teaspoon per 2 gallons of water), which can be convenient and cost-effective over time.

This liquid fertilizer is easy to use—simply dilute with water and apply during regular watering intervals every 2-4 weeks. Made in the USA, it is trusted by many gardeners.

Humboldts Secret Set of A & B Liquid Hydroponics Fertilizer is designed to support both the vegetative and flowering stages of plants, making it suitable for cannabis cultivation. One of its strengths is the complete macronutrient profile, including Nitrogen, Phosphorus, and Potassium (NPK), along with Calcium and Magnesium, ensuring comprehensive plant nutrition. This two-part system is user-friendly, requiring equal application of both bottles throughout the growing cycle, which simplifies the fertilization process for growers.

Additionally, its formulation is pH-balanced and 100% water-soluble, enhancing ease of use across various cultivation mediums, including hydroponics, soil, and coco coir. The fertilizer is suitable for all plant types, which adds versatility for those growing a variety of plants, not just cannabis. However, one potential drawback is that it is not specified whether the fertilizer is organic or synthetic, which might be a concern for some growers aiming for organic cultivation.

Moreover, the product is categorized as quick-release, meaning it might require more frequent application compared to slow-release fertilizers that provide longer-term nutrient availability. Despite these minor shortcomings, the set's ease of use makes it a reliable option for both home and commercial growers looking to enhance their cannabis cultivation.