Unlock the full potential of your leafy greens with our premium water-soluble 8-15-36 formula. High potassium can significantly improve crisp texture and extended shelf life while chelated micronutrients support robust, well-nourished harvests for soil, hydroponic, and foliar growing.
Engineered specifically for leafy green crops. Moderate nitrogen (8%) promotes healthy leaf development without excessive, leggy growth while very high potassium (36%) ensures crisp texture and extended shelf life.
High potassium can help strengthen cell walls for that perfect crunch consumers expect, while supporting post-harvest quality so your greens may stay fresh longer.
Every batch is independently lab tested for heavy metal content so you can grow food for your family or customers with confidence in what you're feeding your plants — and yourself.
Dissolves readily in cold water with zero residue. Suitable for drip lines, NFT channels, aeroponics, and fine mist foliar sprayers when used at recommended concentrations.
Balanced nutrition with moderate nitrogen can help reduce the rapid growth that outpaces calcium transport — a primary contributor to lettuce tip burn. Pair with Cal-Mag Plus to help minimize tip burn risk.
Chelated iron (0.50%) and manganese support rich chlorophyll production for the deep green color that consumers associate with freshness and quality.
Equally effective in garden soil, raised beds, containers, all hydroponic systems (NFT, DWC, ebb and flow, drip, aeroponics), and as a foliar spray. Scales from home gardens to commercial operations.
All six essential micronutrients in precise ratios — iron, manganese, zinc, and copper are EDTA-chelated to prevent lockout in high-pH water, while boron and molybdenum are supplied in highly available mineral forms.
Easily scaled to quarter or half strength for microgreen and baby leaf production. Single applications at low EC deliver complete nutrition for fast-turnover crops.
Registered with the California Department of Food and Agriculture. Third-party lab tested for guaranteed analysis, purity, and compliance with state fertilizer standards.
Our 8-15-36 formula is blended from premium-grade, solution-grade raw materials — each chosen for purity, solubility, and plant availability.
Primary phosphorus and potassium source. Fully water-soluble with low salt index.
Additional potassium plus sulfur for enzyme activation and protein synthesis.
Primary nitrate nitrogen source (7.5% of total N) and additional potassium. Contributes to the clean, rapidly available nitrogen profile preferred by leafy greens.
Supplies the ammoniacal nitrogen fraction (0.5% of total N). Helps lower root-zone pH slightly for improved nutrient uptake in high-pH water.
EDTA-protected iron for chlorophyll synthesis. Stays available even in alkaline conditions.
EDTA-chelated for photosynthesis enzyme activation and disease resistance.
EDTA-chelated zinc for auxin production, growth hormones, and leaf development.
EDTA-chelated copper for lignin synthesis, enzyme activation, and plant structural integrity.
Highly available boron source for cell wall strength and calcium uptake. Not chelated — supplied in mineral form.
Trace molybdenum source for nitrogen metabolism and enzyme function. Not chelated — supplied in mineral form.
Understanding why our 8-15-36 formula works so well for lettuce and leafy greens requires looking at the unique nutritional demands of these crops, where leaf quality, texture, and shelf life are the primary goals.
Supplied as 7.5% nitrate nitrogen and 0.5% ammoniacal nitrogen. The predominantly nitrate form is directly available for rapid uptake, while the small ammoniacal fraction helps moderate root-zone pH. Leafy greens need sufficient nitrogen for chlorophyll production and leaf development, but too much creates overly succulent tissues prone to reduced shelf life, bitter flavors, and increased nitrate accumulation. Our 8% strikes the ideal balance for healthy, flavorful greens.
Available phosphate develops strong, efficient root systems for maximum nutrient uptake, enables rapid ATP production for cellular energy, supports photosynthesis and sugar transport, and promotes early establishment for faster maturity. For a deeper look at phosphorus in plant biology, see What's the Function of Phosphorus in Plants?
Leafy greens are heavy potassium feeders. Potassium regulates stomatal function and water use efficiency, activates over 60 enzyme systems, can help strengthen cell walls for crisp texture, supports overall plant vigor, and may contribute to extended post-harvest shelf life. Learn more in What's the Function of Potassium in Plants?
Chelated EDTA. Essential for chlorophyll synthesis and photosynthesis. Helps prevent interveinal chlorosis (yellowing between leaf veins) that reduces market value in leafy greens. See 8 Reasons Why Plant Leaves Turn Yellow for a full deficiency guide.
Chelated EDTA. Activates enzymes for photosynthesis and chlorophyll formation. Supports overall plant vigor and helps maintain deep green color in leafy greens.
Chelated EDTA. Required for auxin production and protein synthesis. Deficiency causes stunted growth and reduces leaf size — critical issues for leafy green production.
Chelated EDTA. Involved in lignin synthesis for strong cell walls and overall plant structural integrity. Important for enzyme function and supporting plant vigor.
Boric Acid (mineral form — not chelated). Critical for cell wall formation and calcium utilization. Deficiency causes tip burn in lettuce and poor leaf development. Note: do not apply to crops not listed on the label — boron can injure sensitive crops at elevated rates.
Sodium Molybdate (mineral form — not chelated). Essential for nitrate reduction and nitrogen metabolism. Deficiency causes yellowing and poor growth in leafy vegetables. Note: forage crops should not be treated without confirming baseline Mo levels, as elevated Mo can affect ruminant animals.
Strengthens cell walls for that perfect crunch consumers expect in quality lettuce and greens.
Supports robust cell wall structure and general plant health under common production stresses, including environmental variability in controlled growing environments.
Improves sugar content and reduces bitterness for better taste profiles in salad greens.
Maintains freshness days longer after harvest, reducing waste and improving marketability.
Improves stomatal control and drought tolerance for consistent growth even under grow lights.
Helps plants cope with temperature fluctuations, heat stress, and environmental variability.
Below are recommended starting rates for lettuce, kale, spinach, chard, and all leafy green crops. Rates assume RO or rainwater for hydroponic applications — reduce Cal-Mag Plus by 30–50% if using tap or well water with 30+ ppm calcium. Always adjust based on plant size, growth stage, and source-water EC.
| Growth Stage | 8-15-36 Amount | Cal-Mag Plus Stock* | pH Range | EC Target |
|---|---|---|---|---|
| Seedling / Transplant | 0.15–0.25 lbs | 250–500 ml | 5.8–6.2 | 0.8–1.0 EC (400–500 PPM @ 500-scale / 560–700 @ 700-scale) |
| Vegetative | 0.3–0.5 lbs | 500–1,000 ml | 5.6–6.0 | 1.2–1.6 EC (600–800 PPM @ 500-scale / 840–1,120 @ 700-scale) |
| Mature / Harvest | 0.4–0.5 lbs | 1,000 ml | 5.5–6.0 | 1.4–1.8 EC (700–900 PPM @ 500-scale / 980–1,260 @ 700-scale) |
*Cal-Mag Plus stock is prepared by dissolving the entire 5 lb bag in 2 gallons of water. All ml values above are ml of that prepared liquid stock — not dry powder. Shake stock before each use. Do not exceed 2.0 EC for lettuce — higher EC increases tip burn risk. PPM/TDS readings depend on your meter's conversion scale. Use EC for the most accurate measurement. 500-scale PPM = EC × 500 | 700-scale PPM = EC × 700. Most Hanna and HM Digital meters use 500-scale. Most Bluelab meters report EC directly.
Hard water (30+ ppm Ca): Reduce Cal-Mag Plus stock by 30–50%. If your tap water tests above 80 ppm Ca, Cal-Mag may not be needed at the seedling/vegetative stages — test source water EC and Ca first. On RO water, use the rates as published.
Per-gallon conversion (approximate): 0.25 lb / 100 gal ≈ 1.1 g/gal ≈ ¼ tsp/gal | 0.5 lb / 100 gal ≈ 2.3 g/gal ≈ ½ tsp/gal. Teaspoon equivalents are approximate (~4.5 g/tsp). Weigh for precision.
Cal-Mag Plus alone may be light on calcium for tip-burn-prone butterhead and crisphead varieties on RO water. Supplement with Calcium Nitrate:
Vegetative: 0.15–0.25 lbs Calcium Nitrate / 100 gal
Mature / head fill: 0.25–0.45 lbs Calcium Nitrate / 100 gal
Optional on tap water with 30+ ppm Ca. Pre-dissolve Calcium Nitrate separately and add to the reservoir first, before Cal-Mag Plus stock or 8-15-36. Do not exceed 2.0 EC regardless of source water.
Rates assume ~120 plants per 100 gallons (NFT/raft standard, 1.2 plants/gal). Per-plant scaling: a 50-gallon system supports ~60 plants, 25-gallon ~30 plants, 10-gallon ~12 plants. Adjust rates proportionally for denser or sparser plantings. Tip burn is a calcium transport issue triggered by rapid growth at high EC, low humidity, and poor air movement — not a nutrient deficiency that foliar feeding can fix. Prevention: keep EC under 1.8 during head fill, maintain adequate root-zone Ca, ensure air movement across the canopy, and avoid leaf temperatures above 75°F during head fill.
| Purpose | 8-15-36 Rate | Cal-Mag Plus Stock | Frequency / Notes |
|---|---|---|---|
| Supplemental Ca/Mg support | 0.5 lb / 100 gal (~½ tsp/gal) | 10 ml/gal in tank | Weekly during head fill — supplemental support only, not a tip-burn cure |
| Maintenance / general | 0.25–0.5 lb / 100 gal | 5 ml/gal in tank | Every 10 days; very light spray to glistening, not runoff |
| Deficiency correction | 0.75 lb / 100 gal (MAX) | — | Every 5–7 days, max 2 sprays — then address root-zone nutrition. Test small area first. |
Cal-Mag Plus stock ml values refer to prepared liquid stock (5 lb bag dissolved in 2 gallons of water) — not dry powder. Do not combine Cal-Mag Plus concentrate with 8-15-36 concentrate — mix each separately into the diluted spray tank.
Per-gallon conversion (for home sprayers):
0.25 lb / 100 gal ≈ 1.1 g/gal ≈ ¼ tsp/gal | 0.5 lb / 100 gal ≈ 2.3 g/gal ≈ ½ tsp/gal | 0.75 lb / 100 gal ≈ 3.4 g/gal ≈ ¾ tsp/gal
Example: 1-gallon home sprayer at the supplemental rate = ½ tsp 8-15-36 + 10 ml Cal-Mag Plus stock. Teaspoon equivalents are approximate (~4.5 g/tsp).
| Application Method | Rate | Timing |
|---|---|---|
| Per plant (any soil method) | 1–3g per plant (~¼–½ tsp) | Every 2–4 weeks; 1g for seedlings, 3g for active growth, 5g for large heads |
| Pre-plant incorporation | 1 lb / 100 sq ft + 2" compost | Once, before transplant or direct seeding |
| Side-dress (cut-and-come-again) | 0.25 lb / 100 sq ft | Every 2 weeks during active growth |
| Side-dress (head lettuce) | 0.25 lb / 100 sq ft | Single application at heading; reduce 2 weeks before harvest |
| Drip fertigation | 0.5 lb / 100 gal | Weekly during active growth |
| Container — at potting | ½ tsp per gallon of soil volume, mixed in | At potting; top-dress at 3 weeks |
| Container — liquid feed | ½ tsp per gallon water | Every 10 days during active growth |
| Soil drench (seedling) | 0.125–0.25 lb / 100 gal | At transplant |
| Soil drench (vegetative) | 0.25–0.5 lb / 100 gal | Weekly; reduce 2 weeks before harvest |
For a broader look at water-soluble nutrients in hydroponic systems, see What Are the Best Fertilizers for Hydroponics?
Always pre-dissolve each fertilizer in a separate small bucket before adding to the reservoir. If using Calcium Nitrate, add it first. Add Cal-Mag Plus stock second. Add 8-15-36 last. Calcium sources and phosphate-bearing fertilizers must never be combined in concentrated form — doing so can cause precipitation and reduce nutrient availability.
Refer to the Safety Data Sheet (SDS) for complete safety information.
Build a complete leafy green feeding program by pairing 8-15-36 with these essential companions.
Helps prevent tip burn and calcium deficiencies. Commonly paired with this formula for hydroponic lettuce production.
AlternativeAnother calcium source option with a small nitrogen boost for the vegetative stage.
BoostExtra iron for deep green color and enhanced chlorophyll production in leafy greens.
QualityAdditional potassium for improved texture and extended shelf life before harvest.
Leafy greens consist largely of water, and potassium is the nutrient that controls water pressure inside plant cells (turgor pressure). The 36% potassium (as K₂O) can help support cell wall thickness for that perfect crunch, resistance to wilting under grow lights, and post-harvest quality. Without adequate potassium, lettuce tends to become limp and can lose market value more quickly. For a deeper look, read What's the Function of Potassium in Plants?
Lettuce is particularly sensitive to pH. If pH is too high, iron locks out (causing yellow leaves). If too low, calcium locks out (causing tip burn). For hydroponics, keep pH between 5.8-6.2 for the best balance. In soil, aim for 6.0-6.5. Check pH daily in hydroponic systems — lettuce responds quickly to pH drift. For a full guide to yellowing leaves and nutrient lockout, see 8 Reasons Why Plant Leaves Turn Yellow.
Tip burn is a calcium transport issue — calcium isn't reaching the fast-growing inner leaves quickly enough. This fertilizer does not contain calcium because calcium and phosphorus are chemically incompatible in the same solution. You must supplement with Cal-Mag Plus or Calcium Nitrate. Our balanced formula may help by keeping nitrogen moderate (which can reduce excessive growth rate) and providing high potassium (which supports calcium transport within the plant). Note that airflow, cultivar, humidity, and growth rate also influence tip burn risk — nutrition is one part of a complete management approach.
Yes. For baby leaf (3-4 weeks to harvest), use at 50-75% of standard concentration, apply every 5-7 days, and target EC of 0.8-1.2. For microgreens (7-14 days to harvest), use at 25% concentration after cotyledons emerge — a single application is usually sufficient with a target EC of 0.4-0.6.
Calcium and phosphorus are chemically incompatible in concentrated solution. When mixed, they form insoluble calcium phosphate that precipitates out and becomes unavailable to plants. Since our formula contains 15% available phosphate (P₂O₅), calcium must be applied separately. Use Cal-Mag Plus 2-0-0 or Calcium Nitrate 15.5-0-0 as a companion product.
Iron, manganese, zinc, and copper are EDTA-chelated so they remain soluble and plant-available across a wide pH range — particularly in alkaline irrigation water or high-pH growing media where unchelated mineral forms can precipitate out and lock up before reaching plant roots. Boron and molybdenum don't form the same insoluble compounds and are supplied in highly available mineral forms. For a full comparison, see Sulfate vs. Chelated Fertilizers.
Our fertilizer is highly hygroscopic, meaning it absorbs moisture from the air. Keep the bag sealed tight between uses and store in a cool, dry place out of direct sunlight. If it clumps from moisture exposure, simply break it up — the efficacy is not affected.
You might expect a leafy green fertilizer to have very high nitrogen, but too much creates problems: overly succulent tissues prone to disease, reduced shelf life, bitter flavors, and increased nitrate accumulation in leaves. Our 8% provides enough nitrogen for healthy chlorophyll production and leaf development without those downsides. For more on nitrogen's role in plant biology, read What's the Function of Nitrogen in Plants?
Important details on quality, returns, sustainability, and charitable efforts that set our product apart.
If you're not completely satisfied, we offer a 90-day money-back guarantee. Simply return the unused portion in its original packaging, and we'll process a full refund. No questions asked.
We're committed to sustainable practices, including:
1% of all profits go to our foundation, focused on improving educational opportunities for children in agricultural communities.
Family-owned since 1989. Based in Madera, California, we've been making gardens — and their humans — healthier for over 35 years.
Check out our full FAQ page or contact our experts for personalized advice.
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