Feed Me! The Fertilizer Plants Need, Or Don't Need

Why do plants need fertilizer? The simple answer is, they don’t. Left to the natural cycle of life, Mother Nature provides fertilizer to most plants by the breakdown of organic material like leaves, branches, bark, stems and the like, and many of the other elements that plants need occur naturally in our soils. Well, some of our soils. Think about it. No one goes through the Pine Barrens sprinkling or spreading fertilizer and yet millions of pine trees seem to grow there just fine. Also in sand. No one goes down the ocean dunes spreading fertilizer and yet a wide range of plants grow on the top of the dunes, the back of the dunes and even on the salty windswept face of the dunes.

It’s only when man gets involved that we find that our plants need fertilizer. We want our lawns to be lush and green. We want our fruit trees to bear copious amounts of fruit and we want them big and tasty. We want our landscape trees to be large and luscious so they can provide color, texture and size. We want the trees that line our streets and highways to thrive in spite of the fact that they are surrounded by blacktop roads and concrete sidewalks. We want our vegetables to grow fast and taste great and we breed them for those characteristics. All of these are really unnatural states and in order for these plants to perform like this, they need fertilizer.

Then there is the organic versus chemical fertilizer debate. And while you might like to think that plants prefer organic fertilizers to chemical fertilizers, there is little to no evidence to prove this. To the contrary, plants don’t seem to know the difference because there is a chemical and physical reaction in the soil, before the plant roots can absorb these fertilizers or nutrients, that pretty much makes them both end up the same, plant-wise anyway.

The debate over chemical versus organic is much more complex and is more related to how the two are produced, derived and what effect they have on the environment in both their production and once we apply them. But even here there is some debate. While we know that chemical fertilizers can destroy the natural microbes in our soils and can leach into our water table and pollute our streams, bays and aquifers, so can organics. Yes, chemical fertilizers are a primary source of pollution. But when not properly used, organics can do harm as well.

When we look at lawn fertilizers it gets more complicated, but in the end there is one question that has to be answered. We’ll get there. For the examples below we priced out fertilizer based on the amount of nitrogen it contains, as nitrogen is the primary nutrient that a grass plant needs.

If you do the math with one of the most promoted four-step lawn fertilizer programs—and if you follow the entire program—you will be applying about 2 pounds of nitrogen to your lawn every year. This will cost you in the area of $16 for every 1,000 square feet of lawn area. This fertilizer is 100-percent chemical and that includes not only the elements that go into it but also the processing involved in coating the fertilizer and treating it so that it is not released all at once. Then there are the chemicals that are added for weed control and insect control and no one considers these to be benign. So if you have a 15,000-square-foot lawn, you are spending about $230 plus your time to make the four applications.

On the organic side there isn’t an even comparison since we won’t be including weed and insect control and we’ll be making only two to three applications of fertilizer and half the amount of nitrogen, or 1 pound per 1,000 square feet per year. Using the 15,000-square-foot lawn, the cost for this program would be $270 to $360 a year. That’s quite a cost jump for half as much nitrogen. But that’s not the whole story.

Organic fertilizer breaks down more slowly than chemical fertilizer, so it’s naturally “time released.” Organic fertilizer has also been found to increase soil microbes, whereas the chemical fertilizers may tend to kill or reduce them. And since you’re using less fertilizer your grass will grow more slowly and you’ll be cutting it less often. Ah, but will it be as green and lush as your neighbor’s lawn that’s weed-free, insect-free and nearly biologically dead? Maybe, but there’s more to a safe and happy life than a lush carpet of green.

But wait, there’s more. What about your flower garden and your vegetable garden? Let’s start with the vegetable garden. This is where you grow stuff you’ll be eating. Here you may want to be even more careful about what you put into your soil, because it’s going directly into your body. This is where I don’t mess around and I use only organics. But even here there are issues. There is organic—and then there is organic.

I looked at four different brands of fertilizer for the vegetable garden: Coast of Maine, Happy Frog, Dr. Earth and Espoma. Each one tries to lure you in with their own additives like “Pro Biotic” or “Active Soil Microbes,” but don’t be duped by the hype. If you’ve got good soil that you’ve been adding compost to, these additives really don’t matter. And you may find that one company has something like an organic rose fertilizer while another has an all-purpose vegetable fertilizer that has the same analysis, such as 4-4-4, but a very different price—go for the less expensive.

But for the purist among you, the die-hard organic gardeners, there is something to watch out for. Read the bag carefully. Does it say “organic,” or “natural”? Simply, natural does not have to be organic. You will also see that one brand will have the ORMI emblem on it. This is the best assurance of a product’s organic origin and certification. Another may be certified by the Main Organic Farmers and Gardeners Association (MOFGA) … your decision. Watch the Espoma products, though. Espoma has been around a long time but not all their products carry the organic label and some are labeled simply “natural” because they can’t meet the federal standards for “organic.”

In the flower garden I’m not so critical, though I still stick with organics. Here I have no hesitation using Espoma products and the way to save here is to buy the largest bag you can carry as these are the least expensive per pound. You’ll also find that one Southampton garden center’s prices for Espoma products are much lower than the others. Again, be a wise shopper. I doubt very much if your tomato plant is going to know if you’re giving it 3-4-4 or 3-4-6, but you’re wallet may know the difference.

As to the various choices of products, I checked the 4-pound bags of 11 different organic fertilizers at six different locations, including one of the big boxes, a farm supply store and several garden centers. The least expensive I found was in Southampton and it was Rose-tone that came in at 62 cents per pound of fertilizer—not per bag pound. Happy Frog came in at $1.13 per pound for their rose food and Jobe’s organic rose food was $1.09. For organic vegetable fertilizer, Burpee came in at 77 cents a pound and Jobe’s at $1.29 a pound.

But just to give you a flavor for the hype, Jobe’s also has an heirloom tomato food that goes for $1.80 per pound of nutrients while their “regular” organic tomato food goes for $1.29 per pound of nutrients. What’s the difference? One is 2-7-4 and the other is 2-6-4. Bottom line—if you’re a tomato plant—no difference. Keep growing.