Fish Food For Your Roses
by Paulette Mouchet
Originally published in "The Rose Garden" newsletter, June 2003. Updated November 2006.
Ocean products make excellent rose and garden fertilizer because they contain a wide variety of major, macro, and micro nutrients that are sometimes in short supply in land-based fertilizers. Here's a primer to help you sort out the differences between them.
Most of us are familiar with fish emulsion, having used it as a foliar spray. It provides a readily available source of nitrogen, phosphorous, and potassium for our hungry roses. Fish emulsion is a good food source for beneficial foliar bacteria.
Fish emulsion is a by-product of the fishing industry. After fish is cleaned and the meat removed for human consumption, the leftovers are cooked at high temperatures. The fish oil is removed and used for paints and cosmetics. The protein is removed and dried to make fish meal. The remaining water is condensed into the thick, brown liquid we know as fish emulsion.
Even after all this processing, fish emulsion usually retains a "fishy" smell that can attract unwanted animals to the garden. Another problem is that the emulsion contains enough solids that it can clog a hose-end sprayer.
A slow-release, long lasting source of primary macro, secondary macro, and micro nutrients. Fish meal is a great food source for beneficial soil bacteria. The nitrogen in fish meal is stored as protein that is safe from leaching from the soil and is easily accessible by the plant.
To be of benefit, fish meal must be worked into the soil and watered in. If you sprinkle it on top, not only will you get no fertilizing benefit, you'll be visited by unwanted animals who are drawn by the smell.
The newest fish product to reach the consumer market, fish hydrolysate, contains all the vitamins, proteins, amino acids, enzymes, growth hormones, and micro nutrients naturally found in whole fish. The nitrogen and other nutrients are chelated, so they are readily available for the plant's consumption. Best of all, there is no odor. Fish hydrolysate can be applied as a foliar spray or soil drench, and is an excellent food source for beneficial foliar and soil fungi.
Most fish hydrolysate is made from by-catch—unwanted fish caught by accident with the regular catch. Some is made from fish leftovers after the fillets and steaks have been removed for human consumption. The fish by-catch or post-consumer leftovers are ground up and enzymatically digested producing a liquid product. The process is cold—there is little or no heat involved—which protects the beneficial nutrients from damage.
My dictionary defines kelp as "any large, brown, cold-water seaweed of the family Laminariaceae, and seaweed as "any plant growing in the ocean." Thus kelp is seaweed but not all seaweeds are kelp.
Seaweeds contain carbohydrates and amino acids as well as a huge number of beneficial micro nutrients—as many as 60 according to the folks at Neptune's Harvest—and have been shown to
- enhance plant development (particularly root growth), flower color, and vigor
- improve resistance to cold and heat
- improve drought tolerance
Seaweed preparations are often used as a foliar spray but can be applied as a soil amendment or compost ingredient, and they are an excellent food source for beneficial soil and foliar fungi. As with fish meal, dry seaweed products must be worked into the soil and watered in.
Fish hydrolysate is my #1 choice for a liquid fish fertilizer. I've had great results using Neptune's Harvest Fish/Seaweed Blend that combines the benefits of both fish hydrolysate and seaweed in one formula. I used this as both a foliar feed and a soil drench on all my garden plants, not just my roses.