Terpinator: What It Does, How to Use It and Whether It Works

Last updated September 27, 2026 by Shariful Alam Pavel

Scientifically reviewed by Dr. Lukman Syed Rony, PhD, plant microbiologist and Lab Director at Innovate Phytoceuticals. Reviewed September 2026.

Growers buy Terpinator expecting more smell and flavor from the same plants. What the bottle actually contains is simpler than the marketing suggests. Terpinator is a 0-0-4 potassium supplement made from potassium sulfate and a proprietary blend of plant extracts, now sold under the General Hydroponics brand. The manufacturer recommends 5–10 ml per gallon in veg, rising to 25 ml per gallon in late bloom and flush. No independent, peer-reviewed trial of Terpinator has been published. The published research on potassium also gives a reason for caution. This guide explains what Terpinator is, how to use it, what the evidence says, and who should buy it.

Terpinator: key facts

• Terpinator is labeled 0-0-4, meaning 4% soluble potash (K₂O) and no nitrogen or phosphorus.
• Planet Natural lists Terpinator as derived from potassium sulfate and a proprietary blend of plant extracts, with no plant growth regulators (PGRs).
• General Hydroponics directs 5–10 ml per gallon in veg, 10–15 ml in early to mid bloom, and 25 ml in late bloom, ripening and flush.
• Terpinator is a root-feed product; General Hydroponics says not to use it as a foliar spray.
• ScottsMiracle-Gro bought Rhizoflora’s nutrient brands, including Terpinator, on August 16, 2021, for $33.5 million.
• A 2022 Volcani Institute study found most cannabinoids and terpenes decreased as potassium in the feed increased, and recommended about 60 ppm potassium in flower.

What is Terpinator?

Terpinator (sold as Terpinator®) is a liquid plant supplement designed to enhance terpene and resin production in flowering plants. It carries a 0-0-4 fertilizer rating, so its only labeled nutrient is potassium. It is an add-on to a complete base nutrient, not a fertilizer on its own.

Rhizoflora created Terpinator and its color-focused sister product, Purpinator. On August 16, 2021, ScottsMiracle-Gro bought Rhizoflora’s nutrient business for $33.5 million and made its Hawthorne division the main US supplier. The product is now sold as General Hydroponics Terpinator, and older bottles still carry the Rhizoflora name. The formula is marketed to hemp, cannabis, fruit and vegetable growers.

Terpinator 0-0-4, now sold under the General Hydroponics brand

What is in Terpinator?

Terpinator contains 4% soluble potash from potassium sulfate, plus a proprietary blend of plant extracts. The manufacturer does not disclose which plant extracts are used or at what concentration. Retailers describe it as pH neutral, free of plant growth regulators and free of heavy metals.

How does Terpinator work?

Terpinator works, according to its maker, by supplying potassium and plant-derived compounds that support the plant’s own terpene production. It does not add terpenes to the flower. Terpenes are secondary metabolites made in the plant’s glandular trichomes, the resin glands on flowers and leaves.

The potassium part is well understood. Potassium activates enzymes, controls stomata and moves sugars from leaves to flowers. Those sugars supply the carbon building blocks that trichomes use to make terpenes and cannabinoids. The plant-extract part is the unverified piece. The manufacturer has not published which compounds are in the blend or any controlled trial showing their effect.

Terpenes shape a flower’s aroma and flavor. Our guide to the compounds in hemp explains how terpenes and cannabinoids form, and our article on why CBD oil smells covers which terpenes carry the smell.

What does research say about potassium and terpenes?

Research does not show that more potassium means more terpenes. In a 2022 study, Saloner and Bernstein at Israel’s Volcani Institute found most cannabinoids and terpenes decreased as potassium rose from 15 to 240 ppm. They recommended about 60 ppm potassium in flower.

A separate North Carolina State University study by Cöckson, Veazie, Logan and Whipker tested 0–234 ppm potassium. Plants made the most biomass at 234 ppm, but the team recommended 40–80 ppm for healthy growth, with 60–120 ppm as a prudent range. That study did not measure terpenes.

This matters because Terpinator adds a meaningful amount of potassium at the label rates. The table below estimates the potassium Terpinator alone adds to one gallon of feed. It assumes the liquid weighs about 1 gram per milliliter, like water. Your base nutrient adds more potassium on top.

The calculation uses the label’s 4% K₂O and the standard conversion of K₂O to elemental potassium (0.83). These are estimates, not lab measurements. The practical takeaway: if your base nutrient is already potassium-heavy in bloom, full-rate Terpinator can push total potassium far past the levels research links to the best terpene results. Start low and measure your feed’s EC.

How to use Terpinator

Use Terpinator by adding it to your mixed nutrient solution at 5–10 ml per gallon in veg, 10–15 ml in early to mid bloom, and 25 ml in late bloom through flush. Feed it at the roots from veg till harvest. Stir the reservoir, then check pH and EC before feeding.

1. Fill the reservoir with the full volume of water.
2. Add base nutrients first, in the order your nutrient line specifies. If you use a calcium-magnesium supplement, add it before other nutrients; see our Cal-Mag supplement guide.
3. Add Terpinator to the diluted solution, never to undiluted concentrates.
4. Stir, then measure pH and EC. Terpinator is labeled neutral pH, but the full mix may still need adjusting, especially with alkaline tap water.
5. Feed at the roots by hand, drip or reservoir.

Soil, coco and hydroponics

Terpinator works in soil, coco, hydro setups, soilless mixes and hydroponic systems, according to General Hydroponics. In recirculating hydroponics, top off with plain water between changes and re-dose Terpinator only at each full reservoir change. In organic soil or amended potting mix, feed it with your regular nutrient waterings. Mix only what you need for each feeding to avoid waste.

Can you spray Terpinator on leaves?

No. General Hydroponics states Terpinator is not for foliar use. Spraying it on flowers late in bloom can also leave residue on the buds and raise mold risk.

Terpinator supplies potassium during bloom and flush

Can Terpinator be used during flush?

Yes, the manufacturer designs Terpinator for use during flush. General Hydroponics directs its highest rate, 25 ml per gallon, in late bloom, ripening and flush. That means a Terpinator flush is not a true plain-water flush, because it still feeds potassium.

Research suggests the flush itself changes less than growers think. In a 2024 study in Industrial Crops and Products, Saloner, Sade and Bernstein found flushing had only minor effects on yield. Cannabinoids changed in 30% of samples, and terpenes in only 3%. If you flush, you can choose plain water or a Terpinator flush without expecting a large difference in terpene content from the flush alone.

Does Terpinator leave residue in the final product?

Terpinator is marketed as free of plant growth regulators and heavy metals, and its only labeled nutrient is potassium, a mineral plants use naturally. No published test shows Terpinator residues in finished flower. The manufacturer has not published a full ingredient list for the plant-extract blend.

For licensed hemp growers who sell products, the safe step is a residue and heavy-metal panel on the finished harvest. That test covers every input you used, not only Terpinator.

Terpinator vs Purpinator

Terpinator targets aroma and resin, while Purpinator targets color and flavor. Both come from Rhizoflora and are now sold under General Hydroponics. Terpinator is 0-0-4 potassium only. Purpinator is 0-2-4, adding phosphorus alongside potassium.

Fellow growers on Reddit and YouTube often run both together, but those side-by-side videos are rarely controlled trials. If you do, add their potassium to your base nutrient’s and check the total against your target. Other terpene boosters, such as GH Floralicious Plus and Advanced Nutrients Bud Candy, use different ingredients and cannot be dosed the same way.

Is Terpinator worth it?

Terpinator is worth trying only as a controlled test, not as a guaranteed terpene boost. The potassium it supplies is real, but no independent trial shows its plant-extract blend increases terpenes. Research links high potassium in flower to lower terpene levels, so full label rates on top of a potassium-rich base nutrient can work against you.

• Good fit: growers with a light, low-potassium base nutrient who want a single, simple potassium booster in bloom.
• Poor fit: growers already using a potassium-heavy bloom booster, and anyone expecting a dramatic change in smell.
• Best test: run two plants of the same cultivar side by side, one with Terpinator at half rate and one without. Compare a terpene lab test, not just smell.

Retail prices at Planet Natural ranged from $64.95 to $114.95 for the 1-liter and 4-liter sizes in September 2026.

FAQ

Can I mix Terpinator with my current nutrient line?

Yes. General Hydroponics says Terpinator works with other base nutrients and supplements. Add it to the diluted solution after your base nutes, then check pH and EC. Account for its potassium if your bloom booster also supplies potassium.

Does Terpinator increase yield?

No independent trial shows Terpinator increases yield. Retailers claim it improves dry weight and resin gland size, but those claims come from the manufacturer. Potassium supports flower growth only when the base feed is short of it.

Does Terpinator work in hydroponics?

Yes. Terpinator is labeled for hydroponic, coco, soilless and soil systems. In hydroponics, add it at each reservoir change and watch EC, because salts can build up when plants drink water faster than they take up nutrients.

How should you store Terpinator and how long does it last?

Store Terpinator sealed in a cool, dry place away from sunlight, above 40°F and never frozen. General Hydroponics says it stays stable for 2 years sealed. Use an opened bottle within 1 year.

Is Terpinator organic?

Terpinator is made from naturally occurring inputs, according to retailers, but no organic listing is shown on the product pages we checked. If you need certified organic inputs, confirm the current OMRI status with the manufacturer before using it.

How to test Terpinator on your next grow

Before you buy a full gallon, check how much potassium your base nutrient already supplies in bloom. If it is low, start Terpinator at half the label rate in week one of flower and measure EC with every mix. Keep one plant as an untreated control. At harvest, send both to a lab for a terpene panel. If the treated plant does not test higher, stop using it and keep the savings. For the rest of your setup, see our complete guide to indoor hemp farming for CBD, or browse more grower guides in our hemp farming section.

UprightCBD is not affiliated with General Hydroponics, Hawthorne or Rhizoflora and received no payment for this review. Label rates and product details were checked against manufacturer and retailer pages in September 2026; always follow the label on your bottle.