Best Kelp Fertilizer For Plants: 10 Liquid and Meal Options

#1 · Best Overall

1. GS Plant Foods Liquid Kelp

• Form: Liquid
• Weight: 8 lb

Best for: Organic growers covering larger areas.

Why it ranks #1: This dedicated Ascophyllum nodosum concentrate is OMRI listed, suitable for organic growing, and its one-gallon size makes up to 800 gallons.

OMRI listing is the clearest distinction of GS Plant Foods Liquid Kelp, making it a specifically identified option for gardeners seeking a seaweed concentrate suitable for organic production. Its gallon format is labeled to make up to 800+ gallons, fitting use across lawns, gardens, and soil.

The extract is sourced from Ascophyllum nodosum, with listed trace amounts of nitrogen, potassium, sulfur, magnesium, calcium, and other elements; that gives buyers a clear view of its seaweed-based composition. The label identifies root development, chlorophyll production, and nutrient uptake as supported uses. A gallon concentrate making up to 800+ gallons suits broader-area feeding, though the supplied facts do not specify an application rate.

Skip it if you need an exact mixing rate before applying; Bloom City Seaweed and Kelp Liquid Fertilizer lists gallon-based dilution directions.

This GS Plant Foods concentrate suits organic growers managing lawns, gardens, or soil over a broad area. Choose it for its OMRI listing and stated yield, but note that the supplied information does not give a mixing schedule.

Listed on Amazon as: GS Plant Foods Liquid Kelp Fertilizer – Suitable for Organic Growing, OMRI Listed Seaweed Concentrate for Lawns, Gardens & Soil – 1 Gallon (Makes Up To 800+ Gallons)

#2 · Most Concentrated

2. Blue Planet Liquid Kelp

• Form: Liquid
• Weight: 2 lb

Best for: Concentrated multi-system feeding.

Why it ranks #2: The quart concentrate makes up to 470 gallons and lists soil, hydroponic, coco coir, and aeroponic use, offering broad application flexibility.

A quart labeled to make up to 470 gallons gives Blue Planet Nutrients Liquid Kelp a high-dilution format for gardeners feeding multiple planting systems. Its Ascophyllum nodosum concentrate is listed for soil, hydroponics, coco coir, and aeroponics, so one product can serve varied setups.

The stated rate is 1⁄2–2 teaspoons per gallon, with the range supporting adjustment across the listed soil and soilless systems. A single concentrate that makes up to 470 gallons can reduce how often a high-volume grower needs to restock. The formula is described as containing 60+ trace minerals, natural growth hormones, and amino acids, while the directions say to shake the bottle before use—a small but relevant step before measuring.

Skip it if you want a dry kelp amendment mixed into soil; plantonix Kelp Bliss is a kelp meal fertilizer and soil amendment.

Choose this Blue Planet concentrate if you feed soil and soilless systems and want a stated gallon yield with a measured dilution range. It requires shaking before measuring, and its multi-system flexibility may exceed the needs of a single small planting setup.

Listed on Amazon as: Liquid Kelp Seaweed Fertilizer Concentrate – Blue Planet Nutrients Ascophyllum Nodosum Liquid Seaweed Supplement – Makes 470 Gallons – Quart (32 oz)

#3 · Best for Frequent Feeding

3. Bloom City Seaweed and Kelp

• Form: Liquid
• Weight: 2 lb

Best for: Flexible watering and foliar feeding.

Why it ranks #3: Directions give separate grow and bloom rates and permit use with every watering, plus a hose-end ratio for larger areas.

A single liquid kelp formula offers different dilution rates for grow, bloom, and foliar feeding, letting gardeners adjust how they apply it across plant stages. Bloom City lists use with every watering during vegetative growth and bloom, plus a stronger foliar-feed mix for plants at any stage.

For pots and garden beds, measure 5 mL per gallon during the grow phase or 5–10 mL per gallon during bloom, then use it with every watering. The separate 40 mL-per-gallon foliar rate supports a spray-based routine instead. For larger areas, the verified hose-end sprayer guidance gives a 1:200 mix applied once or twice monthly, avoiding the need to water every plant individually.

Skip it if you want a once-or-twice-monthly routine for larger areas; GS Plant Foods Liquid Kelp lists that hose-end application schedule.

Choose Bloom City if you want separate grow, bloom, and foliar directions for pots or beds, with a hose-end option for larger areas. Its every-watering guidance during grow and bloom may not suit less frequent feeding routines.

Listed on Amazon as: Bloom City Seaweed and Kelp Liquid Fertilizer for Plants, 32 oz

#4 · Best Dry Option

4. Down To Earth Kelp Meal

• Form: Granules
• Weight: 8.6 oz

Best for: Organic gardens using dry amendments.

Why it ranks #4: This OMRI-listed granule supplies a stated 1-0.1-2 nutrient formula and suits beds, containers, compost piles, and lawns.

Granular kelp meal gives Down To Earth a dry, slow-release format rather than a liquid feeding routine, making it suited to gardeners amending soil, containers, compost, or lawns. Its listed 1-0.1-2 analysis and OMRI listing add specific guidance for organic garden planning.

The 1-0.1-2 formula supplies slow-release nitrogen and potassium, and the listing says it does so without burning plants. That slow-release approach may suit gardeners who prefer a soil amendment over repeated liquid mixing. Its stated uses span beds, containers, compost piles, and lawns, while the OMRI listing supports use in organic farms and gardens. Rooting and flowering are also named benefits, including for fruit and vegetable growing.

Skip it if you need foliar feeding from a liquid; FoxFarm Bush Doctor Kelp Me Kelp You lists foliar spray application.

Down To Earth suits gardeners who want an OMRI-listed, slow-release kelp meal for soil, compost, containers, or lawns. Its granular format fits amendment routines, but is not the choice for someone seeking a liquid foliar feed.

Listed on Amazon as: Down To Earth All Natural Fertilizers Organic Kelp Meal – 1-0.1-2, 0.5 lb

#5

5. Plantonix Kelp Bliss Meal

• Form: Kelp Meal Fertilizer
• Weight: 2 lb

Best for: Soil amendment for indoor and outdoor plants.

Why it ranks #5: The two-pound kelp meal is described as a soil amendment that supports soil fertility, beneficial microbes, and moisture retention.

Plantonix Kelp Bliss is a dry kelp meal sourced from sustainably harvested sea kelp, giving growers a natural soil amendment that can be used with indoor and outdoor plants. Its listed benefits include mineral and trace-element support, soil fertility, and moisture retention.

Mixed into potting soil, the kelp meal is described as encouraging beneficial soil microbes, connecting the amendment to soil conditions rather than a quick liquid feed. Its natural minerals and nutrients are also stated to support nutrient uptake and soil fertility. The product is further described as helping retain moisture in dry or humid environments, which may matter to gardeners managing changing conditions. The supplied facts do not specify a mixing rate.

Skip it if you need exact liquid dilution instructions; Bloom City Seaweed and Kelp Liquid Fertilizer gives measured per-gallon rates.

Kelp Bliss suits growers who want to work a dry kelp amendment into potting soil or outdoor soil and value its stated moisture-retention benefit. The supplied information does not give a rate, so it offers less guidance for measuring an application.

Listed on Amazon as: Kelp Bliss (2lbs) – Kelp Meal for Plants – Kelp Meal Organic Fertilizer

#6

6. FoxFarm Kelp Me Kelp You

• Form: Liquid
• Weight: 16 oz

Best for: Hydroponic and drip-system feeding.

Why it ranks #6: This Ascophyllum nodosum liquid works with in-ground gardens, drip irrigation, and hydroponic systems, and can be applied as a foliar spray.

Compatibility with in-ground gardens, drip irrigation, and hydroponic systems makes FoxFarm Bush Doctor Kelp Me Kelp You a versatile liquid option for growers using different delivery methods. Its Ascophyllum nodosum seaweed base is listed for fruits, vegetables, and flowers.

The product can be diluted and applied directly to soil or used as a foliar spray, giving gardeners two application routes without changing products. Its listed system compatibility also includes drip irrigation and hydroponics, which helps it fit setups beyond conventional beds. The directions specify applications two to three times in early spring and twice after fruit set, providing a seasonal schedule for those growing fruiting plants.

Skip it if you want a dry amendment blended into potting soil; plantonix Kelp Bliss is a kelp meal soil amendment.

FoxFarm fits growers using hydroponics, drip irrigation, or garden beds who want both soil and foliar application options. Its seasonal directions focus on early spring and after fruit set, so check that schedule against your crop routine.

Listed on Amazon as: FoxFarm Bush Doctor Kelp Me Kelp You Seaweed Plant Food – 0.5-0-0.5 Liquid Kelp Fertilizer for Gardens, Hydroponic & Drip Irrigation Systems – Nutrient Uptake & Plant Growth – 1 Pint

#7 · Best for Transplants

7. Grow More Liquified Seaweed Extract

• Form: Liquid
• Weight: 16 oz

Best for: Seed starting and transplant support.

Why it ranks #7: Its 11% organic kelp formula is positioned for transplant protection and root development, with soil-drench and foliar application options.

Seed germination and transplant-shock support are the main focus of Grow More Liquified Seaweed Extract, making it an option for growers handling new starts or recently moved plants. The liquid seaweed can be applied as a foliar spray or soil drench.

Using either a foliar spray or soil drench gives growers a choice between leaf-level application and watering at the roots during a transition. The formula is described as cold-water-extracted Ascophyllum nodosum, preserving naturally occurring low concentrations of plant growth hormones, including gibberellins and cytokinins. Its listed boron, molybdenum, copper, and zinc provide specific nutrient details, while the supplied facts do not give a dilution rate.

Skip it if you need a listed per-gallon mixing rate; Blue Planet Nutrients Liquid Kelp gives a 1⁄2–2 teaspoon-per-gallon range.

Grow More suits gardeners starting seeds or moving plants who want a liquid seaweed treatment with foliar and soil-drench options. Its cold-water extraction and listed trace elements add detail, but the supplied information leaves dilution instructions unspecified.

Listed on Amazon as: Grow More Liquified Seaweed Extract Fertilizer for Plants – 16oz of Liquefied Natural Liquid Kelp Fertilizer – 11% Organic Kelp Plant Food for Transplant Protection & Root Development

#8

8. TPS Nutrients Seaweed Fertilizer

• Form: Liquid
• Weight: 8 oz

Best for: Houseplants and small garden routines.

Why it ranks #8: This eight-ounce liquid is intended for indoor and outdoor plants, with watering-can directions that vary by season.

A seasonal watering schedule gives TPS NUTRIENTS Seaweed Fertilizer a clear place in routine care: weekly applications in spring and summer, then every four weeks in fall and winter. The liquid is listed for indoor and outdoor plants, including houseplants, containers, and gardens.

For watering-can use, the directions specify 2–4 teaspoons per quart of water, giving growers a defined mixing range for houseplants or container plants. The seasonal schedule adjusts frequency across the year, with weekly spring and summer use and applications every four weeks in fall and winter. The product is also described as supporting root development, plant strength, and foliage health across plant types, including vegetables, herbs, and flowers.

Skip it if you want a concentrate labeled for hundreds of gallons; Blue Planet Nutrients Liquid Kelp states it makes up to 470 gallons.

TPS NUTRIENTS suits houseplant and container growers who want a measured watering-can routine that changes by season. Its per-quart directions work for small batches, while gardeners feeding large areas may prefer a concentrate with a stated higher-volume yield.

Listed on Amazon as: Seaweed Fertilizer – Organic Liquid Kelp Plant Food for All Plants, 8 oz

#9

9. GS Plant Foods Fish and Kelp

• Form: Liquid

Best for: Organic fish-and-kelp garden feeding.

Why it ranks #9: The OMRI-listed liquid combines Ascophyllum nodosum seaweed with fresh fish hydrolysate, so it suits buyers who want a combined plant food.

A blend of North Atlantic Ascophyllum nodosum seaweed and fresh fish hydrolysate distinguishes GS Plant Foods Liquid Fish & Kelp from kelp-only formulas. OMRI listing identifies it for organic growing, with vegetables, flowers, and shrubs named among its intended garden uses.

The combination of seaweed and fish hydrolysate gives this liquid concentrate two named organic material sources, a useful distinction for gardeners choosing a mixed-input plant food. Its OMRI listing supports use in organic growing, and the product description specifically identifies vegetables, flowers, and shrubs. The supplied information does not include a dilution rate or application schedule, so buyers must account for that gap when planning a feeding routine.

Skip it if you want a kelp-only concentrate with a stated dilution range; Blue Planet Nutrients Liquid Kelp lists 1⁄2–2 teaspoons per gallon.

This GS Plant Foods blend suits organic growers who want fish hydrolysate alongside seaweed for vegetables, flowers, or shrubs. Its mixed-source formula is a key fit consideration, and the supplied details do not provide a feeding schedule.

Listed on Amazon as: GS Plant Foods Liquid Fish & Kelp Fertilizer (1 Quart) – Organic Material Review Institute Listed Natural Plant Food for Home Gardens, and Vegetables

#10

10. SUPERthrive Vitamin Solution

• Form: Liquid
• Weight: 4 oz

Best for: Transplant and plant maintenance.

Why it ranks #10: This is a vitamin solution that includes kelp rather than a dedicated kelp fertilizer, though its directions cover transplanting and maintenance.

A drop-per-cup mixing direction makes SUPERthrive easy to measure for small batches, while its stated transplant and maintenance uses give it a focused role around roots and plant transitions. The liquid solution includes kelp and is listed for indoor and outdoor plants.

For a small watering batch, the directions call for one drop per four-ounce cup; larger measures are 1⁄4 teaspoon per gallon or 3 ounces per 100 gallons. That range can fit individual containers or larger mixing volumes. The product is also described for use with fertilizer for growth and for direct use on seeds and roots, connecting its kelp-containing vitamin-solution format to propagation and routine maintenance.

Skip it if you need a concentrate labeled for hundreds of gallons; Blue Planet Nutrients Liquid Kelp states a yield of up to 470 gallons.

SUPERthrive fits growers treating transplants, seeds, roots, or indoor and outdoor plants in small batches. Its clearly stated drop and teaspoon measures help with mixing, while the 4-ounce bottle is a consideration for high-volume feeding.

Listed on Amazon as: SUPERthrive Vitamin Solution with Kelp, Liquid Concentrate, 4 fl oz