20-20-20 fertilizer is the high-concentration balanced feed for water-soluble applications: greenhouses, container plants, hydroponics, foliar feeding, and any setup where you want to deliver nutrients through a watering can or injection system. It is not the right pick for broadcast lawn feeding or for plants in soil that already test high in phosphorus. After comparing 11 popular 20-20-20 products for solubility, micronutrient package, and cost per gallon mixed, these five earned the spot on the shelf.
Quick comparison
| Pick | Size | Form | Best for |
|---|---|---|---|
| Jack’s Classic 20-20-20 | 1.5 lb to 25 lb | Water-soluble powder | Best overall |
| Miracle-Gro All Purpose 20-20-20 | 1.5 lb to 10 lb | Water-soluble powder | Best for houseplants |
| Peters Professional 20-20-20 | 25 lb | Water-soluble powder | Best for greenhouses |
| Plantworks Nutrients GP3 20-20-20 | 1 lb to 5 lb | Water-soluble powder | Best for hydroponics |
| Southern Ag 20-20-20 | 5 lb to 25 lb | Water-soluble powder | Best value |
Jack’s Classic 20-20-20 - Best Overall
Jack’s Classic is the JR Peters professional line repackaged for serious home and small-scale commercial growers. The 20-20-20 formula dissolves cleanly in cold or warm water with no residue at the bottom of the bucket, which matters for injection systems and watering cans alike. The micronutrient package (chelated iron, manganese, zinc, copper, boron, molybdenum) is more complete than most consumer-grade options.
Available in 1.5 pound jars at around $15 up to 25 pound pro bags at around $80. The 1.5 pound jar makes roughly 150 gallons of standard feeding solution, which carries a typical houseplant collection through a full growing season. Mix at 1 tablespoon per gallon for general use.
The right default for serious gardeners, greenhouse hobbyists, and anyone who wants pro-grade nutrients in a small package.
Miracle-Gro All Purpose 20-20-20 - Best For Houseplants
Miracle-Gro is the consumer-side default and the most widely available 20-20-20 in big-box garden centers. The blue powder dissolves quickly and the included measuring scoop makes mixing simple. The micronutrient package is solid for general feeding, though slightly lighter than the pro-grade brands.
Bag sizes range from 1.5 pound jars to 10 pound boxes. A 1.5 pound jar makes about 75 to 100 gallons at the consumer label rate. Cost is mid-range at around $0.50 to $0.70 per gallon mixed. The Miracle-Gro recommended rate (1 tablespoon per gallon) is reasonable but on the high end for sensitive indoor plants. Cut to half rate for houseplants and full rate for outdoor containers.
For households with a few dozen container plants and houseplants, this is the easy default.
Peters Professional 20-20-20 - Best For Greenhouses
Peters Professional is the pro-grade line used by commercial greenhouse operators and serious orchid growers. The 25 pound bag is the standard pack size and runs around $90 to $110 depending on supplier. The formula is essentially identical chemistry to Jack’s Classic 20-20-20 (both made by JR Peters) but with a slightly different packaging and distribution channel.
Solubility is excellent. The micronutrient package is comprehensive enough for greenhouse crops where the only nutrient source is the fertilizer solution. Mix at 200 to 400 ppm nitrogen for constant liquid feed, which is roughly 1 to 2 teaspoons per gallon for daily watering or 1 tablespoon per gallon for weekly feeding.
The right pick for greenhouse hobbyists, orchid collections, and households that grow enough container plants to justify the 25 pound bag.
Plantworks Nutrients GP3 20-20-20 - Best For Hydroponics
Plantworks GP3 is formulated specifically for soilless and hydroponic systems where every nutrient must come from the fertilizer. The micronutrient package is heavier (more chelated iron and trace minerals) than soil-applied fertilizers because hydroponic systems do not have soil to buffer micronutrient availability. The powder is finely milled for fast dissolution in reservoir tanks.
The 5 pound bag runs around $35 and makes roughly 500 gallons of standard hydroponic solution. EC and pH behavior are predictable, which matters for closed-loop systems where solution drift can damage plants in 24 to 48 hours.
The right pick for DWC, ebb and flow, NFT, and other hydroponic systems. Overkill for in-soil container plants.
Southern Ag 20-20-20 - Best Value
Southern Ag’s 20-20-20 is the budget pick for households that want straight balanced nutrient delivery without the brand premium. The 5 pound bag runs around $20 to $25 at farm supply stores. Granules are slightly less uniform than Jack’s or Peters, and the micronutrient package is leaner, but for general container and vegetable feeding the difference shows up only in long-term greenhouse use.
Dissolution is fine in warm water. Mix at 1 tablespoon per gallon for general use. The bag stores well for two to three years in dry conditions.
The right pick for households that fertilize a vegetable garden and a few container plants and do not want premium branding markup. Not ideal for orchid collections or hydroponics where the lighter micronutrient package starts to matter.
How to choose 20-20-20 fertilizer
Application method
Match the product to how you apply. For watering can on houseplants and containers, Jack’s or Miracle-Gro is easiest. For greenhouse injection systems, Peters Professional in the 25 pound bag is the right format. For hydroponic reservoirs, Plantworks GP3 has the better micronutrient package. For occasional vegetable garden use, Southern Ag is the value play.
Micronutrient package
Water-soluble 20-20-20 ranges widely in micronutrient content. Plants growing in real soil get most micronutrients from the soil itself, so a lighter micronutrient fertilizer is fine. Plants in soilless mixes, hydroponic systems, or for extended container growing benefit from a heavier micronutrient package. Read the guaranteed analysis for chelated iron, manganese, zinc, copper, boron, and molybdenum.
Bag size and shelf life
Water-soluble fertilizers store well in dry conditions for two to three years. Buy the bag size that matches your annual use. A 1.5 pound jar makes 100 to 150 gallons of mixed solution, which carries 20 to 30 houseplants through a full growing season. A 5 pound bag carries a small greenhouse hobbyist for a year. Buying too large means storing fertilizer through the off-season, which is fine if kept dry.
Mixing rate
Standard rate is 1 tablespoon per gallon for general use. For sensitive houseplants and seedlings, halve the rate. For greenhouse crops in active growth, the rate may go to 2 tablespoons per gallon under bright light. Always start lighter and increase if growth indicators warrant. Salt buildup in container soil is the most common over-feeding symptom.
Frequency of application
For container plants and houseplants, apply 20-20-20 solution every 2 to 4 weeks during spring and summer when growth is active. Reduce to every 6 to 8 weeks in fall and stop or halve frequency in winter for plants on a normal seasonal cycle. Greenhouse crops under year-round lighting need consistent feeding through winter at slightly reduced rates. Flush container soil with plain water every fourth feeding to leach accumulated salts; this matters more in low-light winter conditions when salt buildup happens faster than the plant can use the nutrients.
Storage conditions
Keep water-soluble 20-20-20 in its original container with the cap firmly closed and stored in a cool, dry location. Moisture exposure causes the powder to clump and harden, which makes it impossible to measure accurately. A garage shelf or basement storage spot works well in most climates. Avoid storing in direct sun or near heat sources. Properly stored, the powder remains effective for two to three years past the manufacture date with no nutrient degradation.
For related reading, see our 10-10-10 fertilizer guide and our orchid fertilizer comparison. Our evaluation methodology covers how we compare garden inputs across application use cases.
20-20-20 fertilizer is the right water-soluble pick for container plants, greenhouses, and active growth phases. Jack’s Classic is the safe default for serious home gardeners. The other four picks above cover the cases (houseplants, greenhouse, hydroponics, value) where Jack’s is not quite the right fit.
Frequently asked questions
What does 20-20-20 fertilizer mean?+
The three numbers are the percentage by weight of nitrogen (N), phosphorus (P2O5), and potassium (K2O) in the bag or jar. A 20-20-20 fertilizer is 20 percent of each, with the remaining 40 percent made up of carrier compounds, micronutrients, and binders. It is twice the concentration of standard 10-10-10, which means smaller bag for the same nutrient delivery and a much higher concentration when dissolved in water.
Is 20-20-20 better than 10-10-10?+
Not better, just more concentrated. 20-20-20 is almost always water-soluble and used for foliar feeding, fertigation, hydroponics, or container plants. 10-10-10 is typically granular and used for in-ground feeding on lawns, shrubs, and vegetable rows. Pick the format that matches your application method. For watering can use, 20-20-20 wins on convenience because it dissolves cleanly. For broadcasting on a lawn, 10-10-10 granules are easier to spread evenly.
How much 20-20-20 should I mix per gallon?+
Standard mixing rate is 1 tablespoon (about 15 ml or 8 grams) of 20-20-20 powder per gallon of water for general houseplant and container feeding. For greenhouse and high-feed crops, 1 to 2 tablespoons per gallon is typical. Always read the specific product label because some brands concentrate differently. Mix in warm water first to ensure full dissolution, then top up with cold water before applying.
Can I use 20-20-20 on indoor plants?+
Yes. 20-20-20 is one of the most common houseplant fertilizers, especially for foliage plants in active growth. Mix at half the label rate (1 to 2 teaspoons per gallon rather than a full tablespoon) to avoid salt buildup in container soil. Apply every 2 to 4 weeks during spring and summer, then stop or halve frequency in winter. Flush containers with plain water every third or fourth feeding to prevent salt accumulation.
Will 20-20-20 burn my plants?+
Yes, if over-applied. Salt burn shows as brown leaf tips, especially on the lower leaves of houseplants and the edges of tomato leaves outdoors. Mixing above the label rate, applying to dry soil, or applying in full midday sun all increase burn risk. Water plants normally first, then apply the fertilizer solution to moist soil. Skip application during heat waves above 90 degrees and never use 20-20-20 on seedlings under two true leaves.
