Fertilizer Confusion

At a local garden center I strolled down the fertilizer aisle and was both amazed and confused. There were rows and rows of fertilizers, most of them organic. There was specific fertilizer for roses, annuals, bulbs, tomatoes, vegetables, etc., etc., etc. Since I grow all of these plants, does it mean that I need a different bag of fertilizer for each one?

The simple answer is no! While these various fertilizers each claim to be for a specific plant, often what’s inside the bags is pretty similar.

When looking at fertilizer, there’s one thing that’s important to note. Each bag of fertilizer has three numbers on it written in a ratio. This ratio is often refered to as N-P-K. The first number is nitrogen, the second is phosphorus and the third is potassium. The numbers tell how much of each nutrient is present in the fertilizer. For example, if you had 100 lbs of a fertilizer labeled 4-3-3, it would contain 4 lbs of nitrogen, 3 lbs of phosphorus and 3 lbs of potassium.

Without getting into all of the details of these three nutrients, in the average garden there are two types of rations that matter. If you’re using fertilizer on the lawn, the numbers should be something like 28-1-2 – a ratio with a large amount of nitrogen since nitrogen leads to a lot of leaf growth. For flowers and vegetables, you’ll want the numbers to be closer together – 4-3-3, 10-10-10 or something similar.

This important N-P-K ratio wasn’t on the front of most of the bags of fertilizer that I saw. I had to look closely at the label on the side of the bag to find it. But when I did find it, I noticed that all of those “special fertilizers” for roses, flowers and vegetables were all pretty much the same. The ratios were very similar. Also I can’t imagine that annual flowers wouldn’t bloom if given a vegetable fertilizer or that the tomato would object to “rose food.”

When it comes to granular fertilizer, I buy two kinds and that’s it. I get lawn fertilizer for greening up the lawn (32-0-4) and I buy a so-called “vegetable fertilizer” for everything else (3-4-4). There are still choices to be made such as the brand and whether it’s organic or inorganic. But limiting my fertilizers to one for the lawn and one for the garden makes shopping in the fertilizer aisle much less confusing.


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