Fertilizer 101: Learn to Love Fish Emulsion

I've been talking with a lot of folks at the market about growing conditions for the herb and vegetable starts that we sell and they'll often mention to me that in previous years, they haven't had good luck with certain crops - particularly basil. Upon hearing this, my first question is: are you growing in the ground or in containers? And if the answer is in containers, my second question is: how often are you fertilizing? Nine times out of ten, I get a shocked look and a hesitant admission of "...Never?" The answer I should be hearing is "Once every week or two!"

Forget container size, forget different potting soils, even forget hours of sunlight: in my opinion, the most important element of successful container gardening is FERTILIZER!

Commercial potting soils are sterilized to eliminate weed seeds, fungal spores, plant-borne diseases, and insect eggs, which is of tremendous benefit when starting seeds. However, sterile potting soil lacks the nutrients that you would find in fertile soil. So for plants to thrive and eventually bear fruit in containers, they need the nutrients they would find in nature - primarily, nitrogen, phosphorus and potassium (or NPK). Fertilizers contain these three primary nutrients, along with others, in varying concentrations.

I won't get into an analysis of the different kinds of fertilizers available commercially - and there are many - because for us, only one will do: fish emulsion. Sometimes called "liquid fish," fish emulsion is a natural fertilizer created from the unusued parts of fish after they've been processed for oil or meat. In addition to NPK, fish emulsion also contains micronutrients that plants need - you've heard about how beneficial cod liver oil can be for humans? Well, plants love fish too. Think too about those stories about Native American planting techniques that we all learned in elementary school, and how they taught the Pilgrims to bury dead fish in the soil when they sowed their crops. Nevermind that said fish (and fish emulsion) can get pretty ripe...the plants don't mind, and you can just breathe through your mouth for the minute it takes to mix up a watering can of fertilizer.

Fish emulsion is a water-soluble fertilizer - that is, you pour a "glob" of it (that's the technical term, by the way) into your watering can, fill with water, and swish it around to dissolve the fertilizer in the water. Once that's done, you can water your plants normally. Aside from the natural benefits of the fish emulsion, we prefer a liquid fertilizer because it's quickly absorbed by the roots of the plants, making the nutrients readily available. It's best to give the plants a drink of water about 10 minutes before you fertilize to minimize the chance of the fertilizer "burning" the roots. (But I freely admit that I rarely follow this dictum because the fish emulsion I use is pretty mild to begin with.)

Be sure to read the instructions on your particular bottle of fish emulsion, since different brands come at different strengths. (The lower the NPK number, the milder the fertilizer - for instance, 1-1-1 is very mild, but 5-5-5 is much stronger and should be used more sparingly & less frequently.)

I fertilize my container-grown plants (basil, tomatoes, chard, elephant ears, zucchini, etc.) with fish emulsion once a week. Perennial herbs in containers should be fertilized only every month or so - their growing requirements are not nearly as intense as those of annuals. With such a regular fertilizing schedule, I'm careful to avoid over-fertilizing - I go a little easy on my "glob" of fish emulsion and dilute it thoroughly in a 2-gallon watering can. In my experience, it's hard to over-fertilize basil and tomatoes with fish emulsion, but I'm sure it is possible. Peppers are a little more sensitive, and herbs like parsley and dill really don't need to be fertilized more often than every two weeks. (Again, I freely admit that I sometimes fertilize the herbs more often than that and they're perfectly happy and rather on the gargantuan side of things.) But the basil? Whack it regularly and fertilize it weekly and you're set. I harvested half a pound of basil from only 3 plants the other night after following that regimen for a while.

If you're going a little heavy on the fertilizer, you'll see a lot of foliage growth but few flowers. If you're not fertilizing often enough, the plant will begin to turn yellow, slow its growth, and eventually die because it can't get the nutrients it needs to survive. As you might have surmised by now, I prefer to err on the side of more fertilizer. But fish emulsion is extremely forgiving because it's natural, mild, and balanced - I definitely couldn't get away with my current fertilization habits with synthetic super-powered fertilizers like MiracleGro with ratios of 18-18-21. (I just looked that up on their website and my eyes nearly bugged out of my head. That's overkill, folks, and synthetic overkill at that.)

There are a number of OMRI-listed brands of fish emulsion available that are approved for organic production - try your local garden center or a store like Lowe's or Home Depot to find bottles of the concentrate. If you don't have any luck in those places, there are a number of fish emulsion brands available online (and it's well worth it). We use enough of it both in the garden and on the pasture that we've graduated to 55-gallon barrels of the stuff. But a quart will go a long way unless you've got a substantial container garden!

I'll try to post some pictures of my container garden later in the week, as I've left my camera at the farm for now. Then you too can bask in the glory of my elephant ears, which impressed even my mother, the Master Gardener!