Fish Emulsion for Orchids: 3 Reasons Why it Works

Fish emulsion, or also known as liquid fish fertilizer, usually has a very low concentration of NPK, (5-1-1 or 5-2-2) so many orchid growers use this in their personal orchid care. I do not, but I’ll get to that later. They usually will switch every other week between their usual fertilizer and fish emulsion. But what is fish emulsion and how does it work for orchids?

When used monthly, fish emulsion is an organic fertilizer that aids orchid growth in both leaves and flower spikes. Since it is high in nitrogen, fish emulsion is fantastic for building chlorophyll and creating strong healthy plant cells. Most all orchid growers have reported benefits from using fish emulsion.

The problem with using fish emulsion only is that it has such a high nitrogen count as compared to phosphorus and potassium that you will need to supplement those eventually. If not, the orchid will receive too much nitrogen and some future problems may occur.

Fish emulsion started as a fertilizing method used before planting crops to enhance the soil nutrition. There are historical records of Native Americans burying the entire fish in the ground and having that decompose before or during the growth of corn stalks. When the years were not as forgiving, just the carcass and scales were buried. With this practice, fish emulsion became widely known and recorded in records at the colonization at Jamestown.

Since fish emulsion is the entire fish, or the majority of the fish, it is a great solution for organic fertilizer, with no added chemicals that can harm your orchids.

If your orchids are heavy feeders, they are perfect candidates for fish emulsion. Some Cattleyas and most all Catasetum are perfect examples.

Fish Emulsion for ORchids
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The Pros of Using Fish Emulsion on Orchids

1) Fish emulsion incentivizes and stimulates the orchid to produce flower spikes. This promotion of the spike is due to the nitrogen boost. I kind of find that odd though, because nitrogen mainly promotes healthy leaf and stem development and increases the production of chlorophyll.

So, there is more to this than meets the eye, but the number one result of using fish emulsion among growers is the appearance of spikes, not healthy leaves. Maybe the leaves just get by-passed in the observations since we all are “spike-focused”.

Nitrogen isn’t the only macro-nutrient in the fish emulsion. It also provides numerous micro-nutrients that are not present in most orchid fertilizers. This means that it’s great as a supplement.

2) Another positive side of using fish emulsion on orchids is that it is relatively fast-acting. Orchids tend to grow at a snail’s pace, so anything “fast-acting” must be taken into context. It’s not going to sprout out new flower spikes in a matter of days, but it will be quicker than if you applied nothing.

3) Since fish emulsion has such low NPK ratios, it’s hard to get fertilizer burn or over-fertilize your orchids with this product. The ratios are perfect for bi-monthly applications, and there is no risk of using too much.

Please note that all store-bought and homemade solutions will require dilution. The ratio will depend on the product that you buy, but the majority say to use one tablespoon per gallon.

The Cons of Using Fish Emulsion

Fish emulsion does wonders on your orchid, but it also breaks down your potting media quicker than other products will. It was initially designed to stay in the soil and release the nutrients as the fish decomposed. In your potting media, this is not the best.

What is available in the market today are foliar sprays with fish emulsion. This is intended to spray on the leaves, and not on the soil or potting media. This leads to another con, which is how much can the orchid leaves absorb? They will absorb some, but orchids are not like other household plants.

You’ll need to spray the underside of the orchid leaf if it is a Phalaenopsis, but what about other orchids? This is not applicable to all orchids.

Another con is about attracting other living things. The smell is atrocious, but some little outdoor critters and creatures love it. So, beware.

Thirdly, this product smells awful. It makes you think of the melting pot of putrid skunk stench mixed with a wet dog. The aroma invokes the regurgitation of all meals ingested in the last week.

One more thing: the smell will persist for two days if you use it indoors, so that’s why I stay away from it. If you have orchids outside or are in a very well-ventilated room, then this might not be a problem.

For olfactory reasons only, I don’t use this product on my orchids. Since I keep them indoors, specifically in my home office, I’d be out of work for weeks at a time.

Is Fish Emulsion and Seaweed the same thing?

Fish emulsion is not the same as seaweed, since they have different NPK properties. Even though fish emulsion has various other elements besides nitrogen, phosphorous, and potassium, such as calcium, sulfur, magnesium, and sodium, it is not considered a stand-alone fertilizer. You need to use another additional fertilizer to upgrade the percentage of NPK.

Seaweed, on the other hand, lacks NPK almost entirely. It has trace elements of various nutrients (mainly enzymes) that are healthy for your orchids but lack the proper Nitrogen, Phosphorous, and Potassium. This means that the orchid will receive nutrients, but not the ones it needs to maintain a long, healthy life.

Liquid seaweed enhances root production on the orchids, has been known to make the orchid more resistant to disease, and in some cases, increased the fragrance of the flowers.

If you want to use liquid seaweed, that’s perfectly fine, but use it as a supplement that you use every other week along with another balanced fertilizer.

To use the seaweed, you’ll need to dilute it in one ounce per gallon. Depending on the seasons of the year and how much you water, you can decrease that to half an ounce per gallon.If you’re wondering how much seaweed fertilizer costs, you can click here Opens in a new tab.(Affiliate Link). If you don’t want the seaweed, but prefer fish emulsion, and you can see the price hereOpens in a new tab. (Affiliate Link).

Extra Notes About Fish Emulsion

I haven’t tried what I’m about to write. But as I close this article, I can’t just walk away without stating the obvious (the formula).

You might want to know how to make your own fish emulsion. The benefit to making your own fish emulsion is that there are beneficial bacteria and fungi that can aid the orchid in the potting media. It’s quite easy, but gross.

You need a can of sardines, or any other fish that you have cut, gutted and cleaned. The sardines are the easiest and fastest way. It doesn’t matter if you have bought the oil or water-based sardines, since both will act in similar ways.

You will also need some sawdust. If that isn’t available in your area, you can try dry leaves. This is necessary to absorb the decomposed fish and have something manageable to throw about on your plants.

To aid in this decomposition process, you need molasses. Most recipes/formulas that I have come across say to use the molasses with sulfur, and others say it doesn’t matter.

Place these items in a big bucket that you don’t ever plan to use again in your life. That smell will penetrate the bucket and it will be so strong that you won’t be able to reuse it.

Layer the fish, leaves, sawdust, molasses again and again until the bucket is ¾ full. Anywhere from half to ¾ is best and fill it with water until the top of the fish is totally covered. More than that, the fermentation might get away from you, and you certainly don’t want this stuff spilling out on the floor.

From this point forward, the times and days vary.

Some authors say to leave this emulsion in the bucket for a few days and stir it often. Others say to leave it a week, stirring it every other day. Some even suggest keeping it a month. I guess I don’t have an opinion about this and never will since I am not trying this.

If you have tried this, please comment below on how long it took for your emulsion to separate and turn into a slimy gook.

Once you are satisfied with your final product, you need to strain the solids from the liquid. You can use an old window screen or mesh to do this. Please be careful to not get this stuff on your clothes. The smell will not come out.

Now you have your final fish emulsion made from home, but please don’t use this exactly the way it is. You’ll need to dilute it before you apply fish emulsion to your orchids. Dilute about 5 ounces into 1 gallon of water. That’s enough to make a difference.

Don’t Stop Learning!

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Orchid Fertilization

Also, if you are looking for an orchid journal to keep your notes specifically about orchid care, check out my 2 solutions for that on this page. If note-keeping isn’t your thing, then there is a free excel spreadsheet that you can download. Click here for more information on how to do that.

If you subscribe to my newsletter, I will send you a 14-page guide on the main tips of orchid fertilizer. It is downloadable and you can print it out on your computer. I designed the guide to double up as a coloring book, just to make it fun.

In all, I wish you the best in your orchid care and happy cultivating.

Signature Amanda Matthews

Amanda Matthews

Amanda Matthews is a theological professor, author, pastor, and a motivational speaker. She's passionate about spreading hope and teaching. Her hobbies include biking, cultivating orchids, and exploring nature trails. She now lives in Kansas, while raising her two children. To read more, go to

3 thoughts on “Fish Emulsion for Orchids: 3 Reasons Why it Works

  1. Thanks Amanda
    Love talking fish emulsion. Been using over 40 yrs on orchids and ferns and everything in between. Used to mix in garbage can and dip fern baskets. In-laws were convinced their daughter had found a nut case.

    1. Hi Steve,
      Thanks for your comment. That is so funny, and I know my family members have the same feeling about me.

  2. Dear Amanda,
    I really enjoyed reading this, as I am heading out to foliar feed my orchids with fish emulsion. My orchids are outside so I can bare the stench. The only being who enjoys the smell is my dog. I would never use this method inside. However, watching my dogs excitement as I fertilize my plants always brings me joy and the orchid seem to love it.

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