Cucumber Fertilizer 8-16-36 | Chelated Micronutrients | Hydroponics, Soil & Foliar Application
Cucumber Fertilizer 8-16-36 | Chelated Micronutrients | Hydroponics, Soil & Foliar Application
Cucumber Fertilizer 8-16-36
Maximize your cucumber and vine crop yields with our premium water-soluble 8-16-36 formula. High potassium supports crisp, great-tasting fruit while chelated micronutrients help ensure complete nutrition for soil, hydroponic, and foliar growing.
Ideal Applications
FEATURES
⚖️ Optimized 8-16-36 Ratio
Engineered specifically for heavy-fruiting vine crops. Controlled nitrogen (8%) prevents excessive foliage while very high potassium (36%) drives crisp, sweet fruit with excellent shelf life.
🥒 Better-Tasting Cucumbers
Adequate potassium supports water balance inside fruit cells and helps reduce the stress conditions that can contribute to bitterness. Consistent nutrition — alongside consistent watering and good variety selection — gives you the best chance of sweet, crisp cucumbers.
🚫 Tested for Heavy Metals
Every batch is independently lab tested for heavy metal content. Our December 2024 analysis by AgroLab/Matrix Sciences shows results consistently well below required limits — so you can grow food for your family or customers with confidence.
🌊 100% Water Soluble
Dissolves instantly in cold water with zero residue. Safe for drip lines, Dutch buckets, NFT systems, and foliar sprayers without clogging risks.
🌸 Enhanced Flowering & Fruit Set
16% available phosphate (P₂O₅) stimulates abundant flower production and strong root systems, reducing flower drop and improving overall yield for continuous harvests.
🛡️ Supports Plant Vigor & Resilience
Adequate potassium supports cell wall strength and overall plant resilience during heavy production. Chelated copper and manganese help maintain the micronutrient availability that supports the plant's own natural defenses.
💧 Soil, Hydroponic & Foliar Versatility
Equally effective in garden soil, raised beds, containers, all hydroponic systems (DWC, NFT, Dutch buckets, drip), and as a foliar spray. Scales from home gardens to commercial greenhouses.
🔬 Complete Micronutrient Package
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.
📦 Better Fruit Shape & Shelf Life
Adequate potassium nutrition helps reduce the risk of curved, bottlenecked, or hollow fruit while supporting firmness for longer storage. Good nutrition is one key factor in market-quality cucumbers — alongside consistent irrigation and variety selection.
📋 CDFA Registered & Lab Verified
Registered with the California Department of Food and Agriculture. Third-party lab tested for guaranteed analysis, purity, and compliance with state fertilizer standards.
DERIVED FROM
Our 8-16-36 formula is blended from premium-grade, solution-grade raw materials — each chosen for purity, solubility, and plant availability.
Macronutrient Sources
Monopotassium Phosphate (MKP) 0-52-34
Primary phosphorus and potassium source. Fully water-soluble with low salt index.
Potassium Sulfate 0-0-53
Additional potassium plus sulfur for enzyme activation and protein synthesis.
Ammonium Sulfate 21-0-0
Ammoniacal nitrogen source that helps lower root-zone pH for better nutrient uptake.
Potassium Nitrate 13-0-46
Nitrate nitrogen and additional potassium. Highly soluble with a low salt index — ideal for sensitive growth stages.
Micronutrient Sources
Chelated Iron EDTA
EDTA-protected iron for chlorophyll synthesis. Stays available even in alkaline conditions.
Chelated Manganese EDTA
EDTA-chelated for enzyme activation in photosynthesis and nitrogen metabolism. Supports overall plant health and micronutrient availability.
Chelated Zinc EDTA
EDTA-chelated zinc for auxin production, fruit development, and growth hormones.
Chelated Copper EDTA
EDTA-chelated copper for lignin synthesis and plant structural strength.
Boric Acid
Highly available boron source for flower development and fruit set. Not chelated — supplied in mineral form.
Sodium Molybdate
Trace molybdenum source for nitrogen metabolism and enzyme function. Not chelated — supplied in mineral form.
SCIENCE BEHIND THE FORMULA
8-16-36: Engineered for Vine Crop Performance
Understanding why our 8-16-36 formula works so well for cucumbers and cucurbits requires looking at the unique nutritional demands of these heavy-fruiting vine crops throughout their growth cycle.
🌿 Nitrogen — 8% (Controlled Growth)
Cucumbers need sufficient nitrogen for vine development, but too much creates excessive foliage, delayed flowering, increased plant stress, and can contribute to reduced fruit quality. Our 8% strikes the ideal balance — enough for healthy green growth without diverting energy from fruit production.
🌸 Phosphorus — 16% as P₂O₅ (Flowers & Roots)
Enhanced available phosphate (P₂O₅) stimulates early root development for drought tolerance, promotes abundant flower production, improves fruit set percentage, and enhances energy transfer during rapid fruit development. The 16% P₂O₅ level ensures robust reproductive growth for continuous harvests.
⭐ Potassium — 36% (Fruit Quality)
Cucumbers are extremely heavy potassium feeders. Potassium supports water regulation within fruit cells, activates enzymes for sugar transport, contributes to cell wall strength and fruit firmness, and helps extend post-harvest shelf life. The 36% helps ensure plants can meet peak demand during fruiting without running short.
Essential Micronutrients
🧲 Iron (Fe) 0.50%
Chelated EDTA. Essential for chlorophyll synthesis. Prevents yellowing between leaf veins that reduces photosynthetic capacity during heavy fruit production. Learn about Chelated Iron EDTA →
⚙️ Manganese (Mn) 0.20%
Chelated EDTA. Activates enzymes for photosynthesis and nitrogen metabolism. Supports overall plant health and helps maintain the micronutrient availability needed during heavy production. Learn about Chelated Manganese EDTA →
🌱 Zinc (Zn) 0.30%
Chelated EDTA. Required for auxin production and fruit development. Deficiency causes stunted growth and small, misshapen fruits. Learn about Chelated Zinc EDTA →
🔗 Copper (Cu) 0.05%
Chelated EDTA. Important for lignin synthesis and plant strength. Helps support structural integrity of heavy fruit-laden vines. Learn about Chelated Copper EDTA →
🧱 Boron (B) 0.10%
Boric Acid (mineral form — not chelated). Critical for flower development and fruit set. Deficiency causes flower drop and cracked, misshapen fruits. Learn about Boric Acid →
🔬 Molybdenum (Mo) 0.001%
Sodium Molybdate (mineral form — not chelated). Essential for nitrogen metabolism and enzyme function. Though needed in trace amounts, deficiency causes yellowing and reduced yields. Learn about Sodium Molybdate →
Why High Potassium for Vine Crops?
🥒 Better Fruit Shape
Adequate potassium nutrition helps reduce the risk of curved, bottlenecked, or misshapen fruits — one factor among several, including consistent irrigation, pollination, and variety.
💧 Reduced Stress-Related Bitterness
Potassium supports water balance inside fruit cells and helps reduce the plant stress that can contribute to cucurbitacin accumulation. Variety genetics, watering consistency, and temperature all play a role as well.
🛡️ Plant Vigor & Resilience
Adequate potassium supports cell wall integrity and overall plant strength during heavy production, helping vines stay productive through the full harvest season.
📦 Storage Quality
Maintains firmness and prevents soft spots during storage and shipping for longer shelf life.
🌱 Continuous Production
Supports multiple harvests by maintaining plant vigor throughout the growing season.
🌡️ Heat Tolerance
Improves stomatal function and water use efficiency, helping plants cope during hot summer months.
APPLICATION RATES & DIRECTIONS
Recommended rates for cucumbers, melons, squash, and all cucurbit vine crops. Select a tab for your growing method.
Rates are per 100 gallons of reservoir and assume approximately 80 plants per 100 gallons (greenhouse trellised standard). These are Greenway's recommended starting rates based on RO/low-EC source water — adjust for your system and water quality. Rates assume RO or rainwater; reduce Cal-Mag Plus by 30–50% on hard tap water with measurable Ca/Mg.
| Growth Stage | 8-16-36 | Cal-Mag Plus | pH | Target EC (PPM 500 / 700) |
|---|---|---|---|---|
| Seedling | 0.25 lbs ~1.1g per plant |
250–500 ml | 5.8–6.2 | 1.2–1.6 EC (600–800 / 840–1120) |
| Vegetative | 0.5 lbs ~2.8g per plant |
500–1,000 ml | 5.8–6.2 | 1.6–2.0 EC (800–1000 / 1120–1400) |
| Flowering / Fruiting | 0.75 lbs ~4.3g per plant |
1,000–1,500 ml | 5.8–6.2 | 2.0–2.4 EC (1000–1200 / 1400–1680) |
PPM 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
RO Water — Calcium Nitrate Supplement
On RO or rainwater, Cal-Mag Plus alone is insufficient for fruit-set calcium during peak cucurbit production. Add Calcium Nitrate as follows:
- Vegetative: 0.30–0.50 lbs Calcium Nitrate per 100 gal
- Flowering / Fruiting: 0.50–0.75 lbs Calcium Nitrate per 100 gal
- Optional: 0.20–0.40 lbs Epsom Salt per 100 gal at fruiting if tissue test indicates Mg need
Pre-dissolve Calcium Nitrate separately. Add to reservoir first, then Cal-Mag Plus, then 8-16-36. Reduce NPK rate by 10–20% if final EC exceeds your stage target. Reduce by ~25% on tap water with 30+ ppm Ca.
Mixing Sequence
- Fill reservoir with target volume of water
- Pre-dissolve each fertilizer separately in a small bucket of warm water
- Add Calcium Nitrate solution (if used) — stir thoroughly
- Add Cal-Mag Plus stock — stir thoroughly
- Add 8-16-36 solution — stir thoroughly
- Adjust pH last; verify final EC before introducing plants
Never combine calcium sources with phosphate fertilizers in concentrated form — calcium phosphate precipitate will form and nutrients become unavailable. Dilution greatly reduces but does not eliminate precipitation risk.
| Purpose | 8-16-36 per 100 gal | Per-Gallon Equivalent | Frequency |
|---|---|---|---|
| Maintenance / boost | 0.5–1 lb ~0.6–1.2g per plant sprayed |
~2.3–4.5g / gal (~½–1 tsp) | Every 10–14 days |
| Pre-bloom push | 1 lb + Cal-Mag stock 5 ml/gal in tank | ~4.5g / gal (~1 tsp) | Once, 7–10 days before first female flowers |
| Deficiency correction | 1.5–2 lbs (MAX) | ~6.8–9g / gal | Every 5–7 days, max 3 sprays. Start at low end. |
Foliar Best Practices
- Apply early morning or late afternoon; avoid open flowers
- Spray to glistening — leaves should be wet but not dripping
- Cover undersides of leaves; add a non-ionic surfactant for waxy cucurbit foliage
- Adjust spray solution to slightly acidic pH (~5.5–6.0) for best leaf uptake
- Stop foliar feeding 7 days before harvest; rinse fruit before use
- Foliar feeding supplements root feeding — it does not replace it
Rates are general guidelines based on typical soil conditions. Actual rates vary with soil test results, plant density, and local conditions. For commercial field production, consult your local extension service or a certified crop advisor. Cucurbits are heavy feeders — pre-plant organic matter significantly improves results.
| Application Method | Rate | Frequency / Timing | Notes |
|---|---|---|---|
| Pre-plant incorporation | 2 lbs / 100 sq ft | Once, before transplant | Add generous compost; cucurbits are heavy feeders |
| Side-dress — vining | 0.5 lb / 100 sq ft | When vines start to run | Band 4–6" from stem |
| Side-dress — flowering | 0.5 lb / 100 sq ft | At first female flower | Band 4–6" from stem |
| Side-dress — fruiting | 0.5 lb / 100 sq ft | At first fruit set | Pair with separate Ca/N program |
| Drip fertigation | 0.75 lb / 100 gal | Weekly during fruiting | Use 25–50% of rate for continuous fertigation |
| Container — at potting | 0.5 tsp / gallon of soil volume | Once at potting | Mix thoroughly into media |
| Container liquid feed | 0.5 tsp / gallon water | Every 2–3 weeks | Top-dress monthly with dry application |
| Soil drench — seedling | 0.25 lb / 100 gal | At transplant | — |
| Soil drench — vegetative | 0.5 lb / 100 gal | Weekly | — |
| Soil drench — fruiting | 0.75 lb / 100 gal | Weekly | Pair with separate Ca/N program |
| Per Acre (field reference) | 200–400 lbs | Split applications | Base on current soil test and crop removal — consult local extension |
Soil Supplement Pairing
- Gypsum (CaSO₄): 3 lbs / 100 sq ft pre-plant for calcium without pH change
- Epsom Salt: Use only if soil or tissue testing confirms magnesium deficiency — container and coco media may need routine Mg supplementation
- Calcium Nitrate: Side-dress 0.25 lb / 100 sq ft monthly during fruiting on arid/sandy soils
HOW TO USE
Soil & Container Growing
- Dissolve the recommended amount in water (1-2 gallons per application).
- Apply in a ring approximately 6 inches from the plant stem, avoiding direct contact with stems and foliage.
- Water thoroughly after application to move nutrients into the root zone.
- Apply every 2-3 weeks during the growing season, increasing frequency during heavy fruiting.
- For best results, supplement with Cal-Mag Plus between fertilizer applications.
Hydroponic Systems
- Fill your reservoir with water to 80% capacity.
- Add Cal-Mag Plus first and stir thoroughly.
- Add Cucumber Fertilizer 8-16-36 and stir until completely dissolved.
- Check and adjust pH to 5.8–6.2 for all stages (fruiting and vegetative).
- Verify EC/PPM levels match your target growth stage.
- Top off to final volume. Monitor and replace solution every 1-2 weeks.
Foliar Spray
- Dissolve at the recommended concentration for your growth stage in a spray bottle or backpack sprayer.
- Apply early morning or late afternoon to avoid leaf burn.
- Spray both upper and lower leaf surfaces until runoff.
- Repeat on schedule during active growth.
- Do not apply during peak sun hours or when temperatures exceed 85°F.
Pro Tip: Always Add Cal-Mag First
When mixing hydroponic nutrients, always add Cal-Mag Plus to your reservoir first and stir thoroughly before adding 8-16-36. Mixing calcium and phosphorus fertilizers simultaneously in concentrated form causes precipitation — you'll see white cloudiness and lose nutrient availability. Adjust pH only after all nutrients are added.
When Cucumber Fertilizer 8-16-36 Is the Right Choice
- Growing any cucurbit vine crop — cucumbers, melons, squash, pumpkins, zucchini, gourds
- Fruiting stage when potassium demand peaks
- Hydroponic systems requiring 100% water-soluble nutrients
- Greenhouse cucumber production at any scale
When to Consider Other Options
- Growing tomatoes or peppers — try Tomato Fertilizer 4-18-38 for higher potassium optimized for nightshades
- Growing strawberries — try Strawberry Fertilizer 8-12-32 for optimized berry ratios
- Growing leafy greens or herbs — try Lettuce Fertilizer 8-15-36 for higher nitrogen balance
- Seedling/early vegetative stage only — consider a balanced formula like Grow Green 4-2-6 until flowering begins
CUCUMBER FERTILIZER CALCULATOR
SAFETY & HANDLING
Personal Protective Equipment (PPE)
- Wear gloves and eye protection when handling dry powder or concentrated solutions
- Avoid inhaling dust — use in well-ventilated areas or wear a dust mask when measuring
- Wash hands thoroughly after handling
Storage Guidelines
- Store in a cool, dry place in the original sealed container
- Product is hygroscopic — it will absorb moisture from the air if exposed
- Keep out of direct sunlight and away from heat sources
- If powder clumps from moisture exposure, break it up — efficacy is not affected
- Keep away from children and pets
Application Precautions
- Do not mix dry fertilizer with other products before dissolving in water
- Do not apply foliar sprays during peak sun hours or when temperatures exceed 85°F
- Avoid direct contact with plant stems and foliage when applying to soil
- Water thoroughly after soil application to prevent root burn
- Boron caution: Apply only to crops listed on the product label — application to unlisted crops may cause serious crop injury
- Molybdenum caution: Do not apply to forage or pasture crops — elevated molybdenum in forage is toxic to ruminant animals (cattle, sheep, goats)
First Aid
- Eye contact: Flush with clean water for 15 minutes. Seek medical attention if irritation persists
- Skin contact: Wash affected area with soap and water
- Ingestion: Do not induce vomiting. Contact Poison Control (1-800-222-1222) or seek medical attention
- Inhalation: Move to fresh air. Seek medical attention if symptoms persist
Refer to the Safety Data Sheet (SDS) for complete safety information.
COMPLETE YOUR SYSTEM
Build a complete vine crop feeding program by pairing 8-16-36 with these essential companions.
Cal-Mag Plus 2-0-0
Supplies the calcium cucumbers need for cell wall integrity and firm fruit development. Critical companion product for both soil and hydroponic growing — apply separately from 8-16-36.
AlternativeCalcium Nitrate 15.5-0-0
Another calcium source option. Provides a small nitrogen boost during the vegetative stage.
BoostEpsom Salt (Magnesium Sulfate)
Magnesium for chlorophyll production. Enhances green color, photosynthesis, and overall plant vigor.
QualityPotassium Sulfate 0-0-53
Additional potassium boost during peak fruiting for maximum yield and quality.
FREQUENTLY ASKED QUESTIONS
Why is the potassium (36%) so high in this formula?
Cucumbers are extremely heavy potassium feeders. Potassium supports water pressure inside plant cells, activates enzymes, and contributes to cell wall strength and fruit firmness. Adequate potassium can help reduce the stress conditions that sometimes contribute to cucurbitacin accumulation and bitterness — though bitterness in cucumbers is also influenced by genetics, heat, irregular watering, and overall plant stress. The 36% level helps ensure plants can meet peak potassium demand during fruiting.
What pH should I maintain for cucumbers?
Cucumbers prefer slightly acidic conditions. For hydroponics, keep pH between 5.8-6.2 during fruiting or 6.2-6.5 during vegetative growth. For soil growing, aim for 6.0-6.5. pH directly affects nutrient availability — outside these ranges, key nutrients like iron and phosphorus become locked out even when present in the solution.
How do I prevent bitter cucumbers?
Cucumber bitterness is caused by cucurbitacin compounds, which accumulate mainly in response to plant stress — heat, irregular watering, poor nutrition, and variety genetics all play a role. Our formula can help reduce nutritional stress because:
- Adequate potassium supports water balance within fruit cells
- Controlled nitrogen helps avoid excessive vine stress
- Balanced nutrition helps reduce the overall stress load that can trigger cucurbitacin production
For best results, combine good nutrition with consistent watering (avoid letting plants dry out), choose low-bitterness varieties where available, and supplement with Cal-Mag Plus during fruit development. No fertilizer can fully offset varietal genetics or severe environmental stress.
Can I use this for greenhouse cucumber production?
Absolutely. Our formula is ideal for greenhouse cucumbers. Use 0.25 lbs/100 gal for seedlings, 0.5 lbs for vegetative, and 0.75-1 lb for fruiting stage. Monitor EC closely — greenhouse plants are more sensitive. Increase Cal-Mag during rapid growth periods and adjust based on variety (European types need higher EC than standard slicing types).
Why doesn't this fertilizer contain calcium?
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 16% available phosphate (P₂O₅), calcium must be applied separately. Cucumbers need consistent calcium for cell wall integrity and firm fruit development — use Cal-Mag Plus 2-0-0 or Calcium Nitrate 15.5-0-0 as a companion product throughout the season.
How do I store the powder?
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.
Can I use this on watermelons and cantaloupes?
Yes. This formula works excellently for all cucurbit crops including watermelons, cantaloupes, honeydew, squash, pumpkins, and gourds. All cucurbits share similar nutritional needs — high potassium for fruit quality, enhanced phosphorus for flowering, and controlled nitrogen to avoid excessive vine growth at the expense of fruit.
GROW WITH CONFIDENCE
Important details on quality, returns, sustainability, and charitable efforts that set our product apart.
Product Quality Guaranteed
- Manufactured in Madera, California, USA
- Tested by independent third-party laboratories for purity and guaranteed analysis
- Registered with the California Department of Food and Agriculture (CDFA)
- Independently tested for heavy metal content by AgroLab/Matrix Sciences (December 2024) — results consistently well below required limits
- 100% chelated micronutrients (Fe, Mn, Zn, Cu) for maximum bioavailability
- Lot-coded for full traceability — every bag can be traced back to its production batch and third-party test results
Hassle-Free Return Policy
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.
Environmental Responsibility
We're committed to sustainable practices, including:
- Recyclable packaging materials
- Precise nutrient formulation to reduce environmental runoff
- Support for integrated pest management (IPM) practices
- Promoting efficient nutrient delivery systems like hydroponics
Charitable Contributions
1% of all profits go to our foundation, focused on improving educational opportunities for children in agricultural communities.
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