Fish emulsion. How and when to use it?

[FairyInTheFlowers]

Well today I decided to buy some fish emulsion and I was wondering how I should use it. Should I use it by itself like an ordinary fertilizer, or should I use it just as a foliar spray, and if so, how often. Would it be okay to mix it with synthisized fertilizers, or would it explode or something? Thanks for any info!

[tucker85]

I think you can do either one. I don't use fish emulsion but I do use Maxicrop Liquid Seaweed. I mix it in with my regular fertilizer. Since I grow outdoors my fertilizer gets on the leaves and in the pots. Some people just use it once a month as a foliar spray by it self. During the summer I use the strength recommended on the label but this time of year I use half the dose. If you're growing inside remember that fish emulsion really smells bad for a day or two.

[Andrew]

I use a trace element fortified fish emulsion at 1/4 to 1/2 the recommended strength on the label for general garden plants, depending on the orchid. Based on Ray's calculator this comes to 150 to 75 ppm N. I use it instead of fertilizing with a synthetic fertilizer; I usually alternate between the two each week. Fish emulsion is a reasonably strong fertilizer so if you are going to add fish emulsion to a synthetic you will need to halve the concentration of each so you don't burn the plants.

Seaweed extract is generally thought of as a conditioner/tonic rather than a fertilizer per se and is not comparable to fish emulsion. Seaweed extract contains a variety of growth regulators but it has almost no nutritional benefit, so adding it to a synthetic fertiliser will not increase the total NPK that much and has little risk of burning your plants.

[beanluc]

The seaweed typically has negligible N, whereas the fish emulsion is a high N fertilizer. so, in my opinion, really not comparable products.

I have heard that orchids really don't absorb from foliar application the way many other plants do. I doubt that it's harmful in any way, but personally I wouldn't make any kind of extra effort to get food on leaves.

Finally: fish emulsion is SO high in N that I make a point of making sure I am also giving sufficient P and K over time. Fish emulsion typically is 5-1-1, that's a very low P and K ratio. I actually don't use fish emulsion on anything but terrestrials and firbark-rooted orchids, as these mediums are the ones which really are known for having bacteria which eat substantial amounts of the N, so they (especially firbark) need high N applications in order for any N to make it up to the orchid.

[Orchid126]

Fish emulsion, being an animal product, can be caustic to orchid roots. If you use it, constantly check the roots for rot or burn.

Liquid seaweed, on the otherhand, being a vegetable product, is very gentle and good for roots. Seaweed can grow as much as a foot a day, and has lots of good micronutrients in it.