Liquid kelp is a natural, seaweed-based fertilizer that improves soil health and helps plants grow stronger. Packed with essential nutrients and growth hormones, it’s a perfect option for anyone wanting to nurture their garden without chemical additives.
Our team carefully reviewed the market to find the best liquid kelp of 2025, focusing on key features like nutrient content, concentration, and ease of use. Our top pick from GS Plant Foods stood out with its certified organic formula and broad coverage, making it a valuable, eco-friendly choice. Read our in-depth guide to make the most informed choice for your gardening needs.
The organic liquid kelp fertilizer by GS Plant Foods energizes plant growth using Ascophyllum Nodosum, a premium seaweed extract approved for organic gardening by OMRI. This eco-friendly formula enhances soil conditions, promotes root mass, and improves nutrient absorption. By boosting resilience to heat, wind, and drought, it fosters healthier, darker foliage and even elevates sugar levels in plants.
One gallon of concentrate yields over 800 gallons of fertilizer, offering exceptional value for gardeners and commercial growers alike. It simplifies application with an easy mixing ratio—just 2 ounces per gallon of water—and is compatible with any sprayer for efficient coverage. Free from harmful chemicals, it nurtures plants while safeguarding the environment. Whether enhancing vegetable gardens, flower beds, or lawns,this liquid kelp delivers powerful results for sustainable gardening, making it our top pick.
| Certification: | OMRI certified organic |
| Source: | Ascophyllum Nodosum |
| Coverage: | Medium |
| Concentration: | 0.3% nitrogen, 0% phosphorus, 0.6% potassium |
| Volume: | 1 gallon |
The liquid kelp fertilizer from Age Old, housed in a 32-ounce bottle, is a natural plant booster derived from premium Ascophyllum Nodosum sea kelp sourced from the North Atlantic Ocean. This powerful formulation invigorates root systems, accelerates seed germination, and provides readily available nutrients for plants. The solution supports both indoor and outdoor greenery, making it a versatile addition to any gardening routine. In addition, it can be applied as both a soil amendment and a foliar spray.
This liquid kelp stands out by enhancing plant resilience in challenging conditions such as heat and drought. While chemical alternatives might offer quick fixes, this natural fertilizer fosters long-term plant health, improving vitality and fortifying plants against environmental stressors. Its ability to nurture soil microorganisms further strengthens the foundation for plant growth, helping plants consistently receive the essential nutrients they need for healthy growth.
| Source: | Ascophyllum Nodosum |
| Coverage: | Medium |
| Volume: | 32 ounces |
| Concentration: | .30% nitrogen, .25% phosphorus, .15% potassium |
FoxFarm’s Bushdoctor Kelp Me Kelp You fertilizer energizes plants with a liquid seaweed extract derived from pure Norwegian Ascophyllum Nodosum. Acting as a natural growth booster, it improves soil health, strengthens roots, and encourages thriving yields for fruits, vegetables, and flowers. Easy to use as a foliar spray or soil additive, this liquid kelp blends effortlessly into your routine and even suits hydroponic setups.
With its eco-friendly formula, this fertilizer offers peace of mind by being safe for children, pets, and the planet, making it an easy and responsible pick for any sustainable garden. For the best results, apply 2-3 times in early spring and twice after fruit set. This schedule not only boosts seed germination and water retention but also enhances fruit quality and strengthens growth cycles. With its mild NPK ratio of 0.5-0-0.5, this liquid kelp is ideal for improving plant vitality and enriching soil health without overpowering your garden. Pair it with a balanced fertilizer to meet your plants’ primary nutritional needs.
| Certification: | OMRI certified organic |
| Source: | Norwegian kelp |
| Coverage: | Medium |
| Volume: | 1 quart |
| Concentration: | 0.5% nitrogen, 0% phosphorus, 0.5% potassium |
Bloom City’s organic liquid kelp and seaweed fertilizer is a standout choice for gardeners who want to nourish their plants with a natural, nutrient-rich formula. It combines seven species of beneficial seaweed and kelp, including Ascophyllum Nodosum and Palmaria Palmata, offering a powerful mix of trace minerals, growth hormones, and natural enzymes. This comprehensive formulation helps improve plant resilience, supports robust growth, and boosts root development.
The liquid form makes it easy to apply and quickly absorbed, providing plants with the nutrients they need without the risk of nutrient burn. Whether you’re tending to houseplants or your outdoor garden, this liquid kelp fertilizer helps keep plants vibrant and healthy. It’s an effective and budget-friendly addition to any gardener’s routine, providing essential nutrients in a clean, natural formula that’s gentle on both plants and the environment.
| Certification: | OMRI certified organic |
| Source: | Seven seaweed species |
| Volume: | 1 quart |
| Concentration: | Not listed |
The Blue Planet Nutrients liquid kelp offers excellent value and a range of benefits for gardeners. The 128 oz bottle of concentrated liquid kelp makes up to 1,890 gallons of nutrient-rich solution—ideal for both small home gardens and large horticultural projects. Derived from organic Ascophyllum Nodosum seaweed, this formulation is rich in trace minerals, natural growth hormones, and carbohydrates that support plant development at every stage.
This liquid kelp is versatile, working well in soil, hydroponics, and coco coir. Its formula boosts plant resilience by promoting stronger roots, healthier foliage, and increased overall growth. The nutrients, including cytokinins and auxins, help stimulate cell division and elongation, contributing to more vigorous growth and better stress resistance. Plus, it’s safe for frequent use and won’t cause nutrient burn or imbalance, making it an ideal choice for long-term plant health.
| Certification: | Not listed |
| Source: | Ascophyllum Nodosum Seaweed |
| Volume: | 128 ounces |
| Coverage: | Medium |
| Concentration: | Not listed |
If you’re looking to give your garden a powerful nutrient boost without the added chemicals found in some fertilizers, kelp liquid is the perfect solution. Packed with essential minerals and growth-enhancing compounds, this seaweed-derived supplement can help your plants flourish in ways you might not have imagined. In this guide, we’ll break down the top factors to consider so you can choose the best liquid kelp for your needs!
The source of your liquid seaweed extract matters significantly. High-quality fertilizers are typically sourced from clean, cold waters where the seaweed is less likely to be contaminated by pollutants. Look for kelp that is sustainably harvested to protect the environment and future resources. Some brands may also share their harvesting practices, ensuring that their fertilizers are eco-friendly and responsibly sourced.
When choosing a kelp liquid fertilizer, it’s important to understand its nutrient profile. Kelp is known for its rich content of essential trace minerals, like potassium, magnesium, and calcium, which promote plant health and vitality. Check if the fertilizer includes additional micronutrients or beneficial compounds, such as amino acids or growth hormones, which can further enhance the effectiveness of the solution. A balanced nutrient profile ensures your plants get the nourishment they need to thrive.
The concentration of the solution plays a vital role in its effectiveness. A more concentrated formula requires less liquid to achieve the same results, making it a more economical option in the long run. Purity is just as essential—make sure that the solution is free of unnecessary fillers or additives that could dilute its beneficial effects. Pure, high-quality liquid seaweed extract should have a distinct seaweed odor and a dark color, a sign that the nutrients have been properly preserved.
Different kelp liquid fertilizers may have varying application methods depending on your needs. Some options come as concentrated formulas that need to be diluted with water, offering flexibility in how you apply them to your plants. Others may be ready-to-use, which can be more convenient for smaller gardening projects. Be sure to follow the manufacturer’s instructions for the best results, and keep in mind that the method you choose will depend on your specific gardening goals.
While organic kelp solutions are often priced higher than conventional fertilizers, they provide significant value in the long term. Consider the amount of solution you’ll be able to create from a single bottle and how long it will last before making a purchase. For those looking to balance affordability and quality, investing in a highly concentrated liquid kelp fertilizer can be a wise choice.
When making any purchase, it’s always helpful to consider the brand’s reputation. Look for companies that are transparent about their sourcing, production processes, and testing practices. Reading customer reviews can give you valuable insights into the effectiveness of the fertilizer and how well it works for other gardeners. A trusted brand is more likely to offer a high-quality organic kelp solution that delivers on its promises.
To use liquid kelp, dilute it with water according to the instructions on the label and apply it to the soil or foliage using a sprayer or watering can.
Yes, liquid kelp is safe and beneficial for all types of plants, including vegetables, fruits, flowers, and indoor plants.
For best results, apply liquid kelp every 2-4 weeks during the growing season, adjusting the frequency based on plant type and specific growth needs.
Yes, liquid kelp is safe for edible plants and can enhance the growth and yield of vegetables and fruits without introducing harmful chemicals.
Liquid kelp promotes stronger root development, improves nutrient uptake, enhances resistance to environmental stress, and boosts overall plant health.
Yes, liquid kelp can be mixed with other fertilizers or pesticides, but it's always best to conduct a compatibility test on a small area before full application.
If you overapply liquid kelp for gardening, thoroughly water the plants to help dilute the solution and minimize any potential adverse effects.
While organic liquid kelp fertilizer is stable for a long time, it's best to use it within 2-3 years of purchase for maximum effectiveness.