Bloom Fuel 4L

Grotek Bloom Fuel 4L (sold by Grotek as Bud Fuel Pro) is a 1-3-4 NPK liquid flowering supplement built on fermented molasses, kelp, monopotassium phosphate, and diammonium phosphate. It is dosed at 2–3 ml per litre of water as a root drench, three to four times across the flowering cycle, alongside your regular flower-feed program in soil, peat or coco soilless, and water culture hydroponics.

Bloom Fuel 4L Specifications

The figures below come from Grotek’s published guaranteed analysis and application guidance for Bud Fuel Pro, the product DS Urban Farm and other retailers list as Bloom Fuel 4L.

Specification	Value
Brand	Grotek
Manufacturer product name	Bud Fuel Pro (retailed as Bloom Fuel)
Supplier SKU	UF18681
Container size	4 L (also available in 500 ml, 1 L, 10 L, 23 L)
NPK guaranteed analysis	1.0 N – 3.0 P2O5 – 4.0 K2O
Derived from	Fermented molasses, kelp, monopotassium phosphate, diammonium phosphate
Formulation	Liquid concentrate, high-solubility
Application method	Root drench
Standard dose	2–3 ml per 1 L water (≈ ½–¾ tsp per 1.25 qt)
Dilution ratio	1:500 — one litre concentrate makes 500 L of feed solution
Feeding frequency	3–4 times per growing season, mid-veg through early bloom
Compatible growing systems	Soil; peat or coco soilless; water culture hydroponics
Product type	Flowering supplement / bloom additive (not a standalone fertilizer)
Third-party organic certifications	None listed on the Grotek product page

Why Choose Bloom Fuel 4L

Bloom Fuel sits in a specific slot in a feeding chart: it is the additive that pushes the plant out of vegetative growth and into a flowering response, then keeps the bloom phase fed with extra phosphorus and potassium. It is not designed to replace a base nutrient, and Grotek is explicit on that point — it must run alongside a flower-stage feed.

• Targeted 1-3-4 ratio. Low nitrogen keeps vegetative push restrained while phosphorus (3%) and potassium (4%) line up with the plant’s increased demand at flower set and early bloom.
• Mineral and organic blend. Monopotassium phosphate and diammonium phosphate provide fast-uptake mineral P and K; fermented molasses and kelp supply carbohydrates and bio-active compounds that feed root-zone microbial activity.
• High-solubility liquid. Mixes cleanly into reservoirs without residue, so it is workable in drip lines, hand-watering, and recirculating hydro setups.
• 4 L size suits multi-room and small-commercial growers. At a 1:500 dilution, a single 4 L jug makes 2,000 L of feed solution — enough to carry a tent or small flower room through several full cycles, or a single larger room through a complete bloom run.
• Grotek’s stated formulation goal is to optimize the soil nutrient profile for flower growth and root structure — the additive is positioned to support the transition window rather than a late-flower finisher.

If you are already feeding a balanced base nutrient and want a single additive that covers the pre-flower and early-bloom phase without rebuilding your whole feed chart, Bud Fuel Pro is built for that slot.

Best Uses for Bloom Fuel 4L

• Pre-flower transition feeds. Add Bud Fuel Pro to your reservoir starting roughly halfway through vegetative growth to encourage the move into bloom. This is the application Grotek calls out specifically.
• Early-bloom support in soil and coco. Use as a 2–3 ml/L drench during the first weeks of flower to back the base nutrient with extra P and K while flower sites are setting.
• Recirculating hydroponics with a separate base feed. Dose into the reservoir alongside a flower base, keeping EC inside the range your strain tolerates and verifying with runoff or reservoir readings.
• Mixed-stage tents. Growers running staggered plants can add Bud Fuel Pro only to the late-veg and early-flower plants while leaving early-veg plants on a vegetative feed.
• Programs that already include a microbial input. The kelp and molasses content pairs naturally with biological additives such as Advanced Nutrients Tarantula 250 ml for growers who want to support root-zone microbial activity through the transition.

Bloom Fuel 4L vs Green Planet Dual Fuel 1

The closest in-catalog comparison is Green Planet’s Dual Fuel 1 (1 GAL / 4 L), another liquid bloom additive sold in a comparable 4 L size for the same pre-flower / early-bloom window. The two products overlap in use case but differ in nutrient emphasis.

Dual Fuel 1 runs a 1-3-2 analysis, weighting phosphorus over potassium. Bud Fuel Pro carries the same 1% nitrogen and 3% phosphorus but doubles potassium to 4%. For growers whose strains or substrate already drink potassium hard at flower — heavy coco programs, or strains prone to early-flower K deficiency — Bud Fuel Pro’s 1-3-4 is the closer match. For programs that lean on a separate potassium source later in bloom, Dual Fuel 1 may slot in better.

The other commonly compared additive in this slot is General Hydroponics KoolBloom (0-10-10). KoolBloom is a different animal — no nitrogen at all and far heavier P and K — designed for mid-to-late bloom finishing rather than the vegetative-to-flower transition Bud Fuel Pro targets. Both can sit in the same feed chart at different stages.

Price-wise, this 4 L bottle is listed at $77.97 on Premier Hydro; the Dual Fuel 1 equivalent gallon is in the same retail bracket, so the choice usually comes down to NPK fit and whether you want kelp and molasses in the blend (Bud Fuel Pro) or a straight mineral additive (Dual Fuel 1).

Compatibility & Operating Range

Grotek lists Bud Fuel Pro as compatible with three growing-system families:

• Soil — standard potting mixes and outdoor beds, applied as a root drench at the standard dilution.
• Soilless (peat and coco) — coco coir and peat-based mixes; pair with a coco-specific or general flower base, since coco’s cation-exchange behaviour can shift available potassium.
• Water culture (hydroponics) — DWC, recirculating reservoirs, and drip-to-waste systems. Mixes cleanly into the reservoir and does not require pre-dissolving.

It is designed to layer on top of a flower-stage base nutrient, not to replace one. Growers running a soluble organic program built on molasses-style carbohydrate sources should keep an eye on total carbohydrate load if they are also using a heavy molasses input such as Earth Juice Hi-Brix Molasses, since Bud Fuel Pro already brings fermented molasses to the mix.

No operating-temperature window is published for the concentrate beyond standard liquid-fertilizer storage practice — keep the bottle out of freezing temperatures and direct sunlight, shake before measuring, and use within a reasonable shelf-life window. Adjust pH of the final feed solution to 5.8–6.2 before applying, which is the standard range for most flower-stage feeds in soil, coco, and hydro.

Dosing Guidelines

Grotek’s published rate for Bud Fuel Pro is 2–3 ml of concentrate per 1 L of water, equivalent to roughly ½–¾ teaspoon per 1.25 quarts. At that rate, one litre of concentrate makes 500 L of finished feed solution, so the 4 L jug yields 2,000 L of solution at the standard dose.

Water volume	Bud Fuel Pro dose (2 ml/L)	Bud Fuel Pro dose (3 ml/L)
1 L	2 ml	3 ml
4 L	8 ml	12 ml
10 L	20 ml	30 ml
20 L (≈ 5 gal)	40 ml	60 ml
100 L (≈ 26 gal)	200 ml	300 ml

Frequency: Apply three to four times across the growing season. Time the additions to the pre-flower and early-flower window — the first application around mid-veg to trigger the flowering response, then subsequent applications across the first weeks of bloom while flower sites are setting.

Layering: Bud Fuel Pro is not a standalone feed. Mix it into a finished feed solution that already contains your base flower nutrient, then apply as a root drench. Run an EC check after combining to make sure the total feed strength is still within your strain’s comfort window.

How to Mix & Apply Bloom Fuel

1. Shake the concentrate. Invert and shake the 4 L jug for 10–15 seconds to redistribute any settled solids before measuring. The fermented-molasses and kelp content can settle slightly during storage.
2. Mix your base flower nutrient first. Add your flower-stage base feed to the reservoir or watering can at its label rate and stir until fully dissolved.
3. Measure Bud Fuel Pro. Use a calibrated syringe or measuring cup to draw 2–3 ml of Bud Fuel Pro for every 1 L of final feed solution. Stick to one rate within the 2–3 ml/L window for the run rather than alternating.
4. Add to the mixed solution. Pour the measured Bud Fuel Pro into the reservoir or watering can while stirring. Mix thoroughly for 30–60 seconds.
5. Check pH. Test the final solution and adjust to 5.8–6.2 for most soil, coco, and hydroponic flower programs. Adjust after Bud Fuel Pro is added, since additives can shift pH.
6. Apply as a root drench. Water the plants at the base, distributing the feed evenly across the root zone. In hydro, simply add the mixed solution to the reservoir.
7. Record and review. Log the application date and rate, then watch the plants for the next 5–7 days. Look for improved flower-site development; if EC or pH drift outside your target, adjust the next mix.
8. Repeat 3–4 times per season. Schedule the next application based on the plant’s growth stage, keeping all dosing inside the pre-flower and early-bloom window Grotek specifies.

Sources & Further Reading