1. How do I use Physan 20?

Physan 20 can be used in many different ways:

  • Primarily as a rescue remedy on all Orchids for Crown Rot, Erwinia and Boytritis
  • All round Disinfectant to decontaminate pots, floors and workbench areas in the Greenhouse
  • Sterilizing agent for Greenhouse tools and equipment
  • Maintenance spray to combat and control Fungal diseases on flowers and plants
  • Clean out and sanitise closed hydroponic Irrigation systems
  • Controls Algae on walkways, paths and hard garden surfaces
  • De-flasking and soil drenching
  • Controlling algae in fountains, birdbaths, swimming pools and decorative water displays

Download Full Physan 20 Imperial Measurements Product Booklet here:

Download Full Physan 20 Metric Measurements Product Booklet here:

2. What plants can I use Physan 20 on?

Physan 20 can be used on all sorts of plants! Below is a chart showing some of the plants and diseases that are treatable with Physan 20. The Green dots indicate that Physan 20 is effective. Download Usage Guide PDF here:

Download Full Physan 20 Imperial Measurements Product Booklet here:

Download Full Physan 20 Metric Measurements Product Booklet here:

3. Can I use Physan 20 in my hydroponic system, and if so, what ratio should I use while my plants are growing in there?

Absolutely. Physan 20 is safe to use in the presence of plants and typically we recommend using a ratio of 1mL of Physan 20 to 40 Liters of water. This rate can be applied every 10-14 days to help control algae and protect roots against pathogens.

4. What is Parts Per Million (PPM) of Physan 20 when applied in hydroponic systems?

At the rate of 1ml per 40 litres of water, and the PPM of Physan 20 is 5.

5. If I'm adding beneficial bacteria to my reservoir, will Physan reduce the beneficial effectiveness since it is a bactericide?

Typically we recommend staggering Physan 20 application with that of nutrient/beneficial feeding. While Physan 20 will not completely nullify the beneficial bacteria, Physan 20 cannot determine the difference between beneficial and harmful bacteria when present in the reservoir.

6. Do I need to wear any protection when using Physan 20?

It is recommended you use protection when handling Physan 20 in its concentrated form, however, when diluted with water it is completely safe to use. Gloves and specialised safety equipment are not required.

The diluted Physan 20 solution is safe enough to dip ones hands in. It is not a primary eye or skin irritant, and if splashed on clothes will not harm them. The solution is pleasant smelling and requires no special ventilation to use.

7. Is Physan 20 Toxic for my dog?

In it's concentrated form, Yes, however once diluted it is safe for all birds and mammals. Physan 20 is only toxic to fish as it clogs up their gills and impedes breathing. Do not use it on your water feature if there are fish swimming around. Physan 20 is Bee Friendly, and will not harm your local insects, birds or mammals.

8. Is it safe to clean my pool and House with Physan 20 if I have children around?

Absolutely, when diluted with water Physan 20 is safe to use around all children and pets - EXCEPT FISH.

9. Is Physan 20 environmentally Friendly?

Physan 20 is one of the few disinfectant products of the market which is EPA approved and bio-degradable. 

10. How long does Physan 20 last for?

When left in the bottle in its concentrated form Physan 20 can last up to 10 - 15 years.

When diluted it can last up to a week - a simple way to check if the solution is still active is to give it a little shake, if you see slight soap bubbles this indicate the solution is still active and can be used. 

Physan 20 has residual germicidal activity, which means it remains effective for a period of time, particularly on hard surfaces. The solution itself remains active and can be used over time. In addition, a 10 minute contact time is all that is required to disinfect.

Physan 20 is a naturally long lasting contact fungicide. When applied, it leaves a bacterio-static barrier and serves as an excellent wetting agent, performing and lasting much longer than other Fungicides on the market today.

11. What are the benefits of using Physan 20?

  • Broad spectrum disinfectant with a huge variety of plant and surface applications
  • Environmentally friendly and biodegradable - EPA approved for direct use on plants
  • Gloves not required for use with diluted solution and is safe for use around children, mammals and plants.
  • Highly stable product with a Long shelf life that retains antiseptic and germicidal properties for years compared to hydrogen peroxide, chlorine bleach, and alcohol
  • Available in a cost effective concentrate meaning a little goes a long way
  • Non-flammable
  • Excellent wetting agent - Long lasting
  • Pleasant odor and does not discolor skin
  • No need for respiratory gear, jump suits or specialised safety equipment.
  • It stands alone on the NZ market as there is no product remotely like it

12. Should I disinfect my tools with Physan 20?

Absolutely, Physan 20 is particularly useful when it comes to disinfecting cutting tools in the green house. Simply mix a solution in a vessel and dip your tool in for 8 to 10inutes. You can use Physan 20 to disinfect your work areas, benches, pots, flats and flower buckets too! Dilution rates for these applications are as follows:




Disinfect Cutting Tools 4 teaspoons Physan20 per 3.7 litres of water
Mold/Mildew Control on Surfaces 1 1/2 Tablespoons Physan20 per 3.7 Litres of water
Disinfect Work Areas and Benches 1 Tablespoon Physan20 per 3.7 Litres of water
Disinfect Pots/Flats/Flower Buckets 1 Tablespoon Physan20 per 3.7 Litres of water

13. How does Physan 20 work?

Physan 20 disrupts the cell membrane of the Pathogen to destroy and/or disable it from affecting the plant. It has an inherently high wetting and penetrating action that provides a deep and intimate contact between the antiseptic-germicide and any microorganisms, dirt e.t.c. When used an almost unseen residual anti-bacterial film is left on the surface, this film prevents and inhibits the growth of micro organisms over a period of several days. Download Technical Data PDF here:

14. Does water temperature affect Physan 20's effectiveness?

Physan 20 is effective in either hot or cold water, however it's effectiveness increases with a higher water temperature.

15. Will Physan 20 change the PH level of my soil?

Physan 20 concentrate is a very stable PH neutral compound and will not effect the pH of any potting mix/dirt. The PH ratings of Physan 20's aqueous solutions fall within the range of 6.5 to 7.5. Physan 20 is cationic in its reaction to surfaces throughout the entire PH range and maintains its bactericidal effect throughout the whole PH range. In addition when used in application, Physan 20 is heavily diluted down with water and will maintain its neutral pH.

16. Is Physan 20 compatible with other sprays and can it be mixed with other chemicals?

Physan 20 can be mixed with some chemicals without problems as it is typically a soap compound so It won’t cause any harm. However, take note that if mixed with another product, it may impede Physan 20 from contacting the surface your cleaning thereby compromising its disinfecting abilities. Check page 3 of the Technical Data PDF for more info.

17. Can Physan 20 be used on Vegetables, fruit or plants intended to be smoked or consumed?

Yes, Physan 20 can be used on these sorts of plants. Physan 20 is widely used on tobacco plants to control Tobacco Mosaic Virus (TMV) and there are no problems with using Physan 20 on a smokable product. We recommend to halt the use of Physan 7 days prior to clipping any buds or leaves. Physan 20 breaks down into the organic element Nitrogen after 7 days, so there is not a chemical residue left over that would be harmful if smoked or ingested. Physan 20 is also non-systemic, so customers can feel confident that Physan 20 will not harm individuals consuming any plant material that has had previous contact with Physan 20. 

18. Can Physan 20 be used on metal machinery or plastic?

A mixed solution of Physan 20 to the correct dilution as specified in the handbook is non-corrosive to all metals and plastics. It will not damage or mar natural rubber, glass and painted plastic surfaces. Download Technical Data PDF here:

19. Is physan 20 a hazardous chemical?

Yes, Physan 20 is classified by MPI NZ as a class 8 Dangerous good. You can download the entire Safety Data Sheet Here for all the information you need.

20. Why is Physan 20 so heinously expensive to ship or deliver?

Physan 20 is classified as a class 8 Dangerous good, therfore it cannot be handled by your average post office or courier company. By law we are required to use a specialised dangerous goods delivery company. We use ChemCouriers as they are the cheapest alternative we have been able to find in New Zealand by a long shot.

It is also important for us to state that we are not making a profit or marking up any of the delivery charges. What you are seeing is the true Delivery cost.

For more info on delivery just visit our Delivery Info Page