Fertilizer (Plant Food) 101

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Those of us with teenage kids or grandkids probably know all about texting.  Of course we don’t know all the short cuts but LOL (laugh out loud) and OMG (oh my gosh) are pretty common.

But do you know NPK?  In the gardening world this is vital information.  Each bag, bottle, jar, or jug of fertilizer will have three numbers on the back, such as 10-10-10 or 5-10-5, representing the percentage of nitrogen, phosphorus, and potassium that is available in each bag.  (Technically it represents the percentage of N, P2O2, and K2O that is available, but for our purposes, nitrogen, phosphorus, and potassium will do.)

Now you’re probably thinking 5 plus 10 plus 5 only adds up to 20% -- what’s in the other 80% of the bag?  Depending on the brand of fertilizer, the rest of the bag may contain some minor nutrients and filler material.  The filler material allows us to apply the nutrients evenly across the area we want to fertilize.  Without the filler material, we would over apply nutrients in some parts of the area and under apply in others.  In other words, the filler material allows for a uniform application of nutrients.

So let’s talk about what each number (letter) really does for your plants.

N -- Nitrogen -- This nutrient provides dark, green color and rapid growth.  It also improves the yield and quality of leaf crops (such as lettuce, collards, kale, and chard).  It also enhances protein content of food crops.  Nitrogen aids in stress tolerance and disease resistance (in plants that is -- I’m not sure about humans).

P -- Phosphorus -- stimulates early root growth and plant vigor.  It also influences blooming and seed formation which makes it great for punching up the color of blooming annuals.  Phosphorus also imparts winter hardiness in grasses and perennials.

K -- Potassium -- mostly helps stem and stalk stiffness but also encourages rooting, vigor, protein formation, fruit quality, as well as disease resistance.  Potassium is essential in the formation of plant starches, sugars, and oils which makes it good for herbs where the essential oils make up their flavor.

Now let’s talk a little bit about chemical vs. organic fertilizers.  I know you’re all thinking organic fertilizer -- she must mean cow manure.  Well, yes, that is one but all three -- N-P-K -- are naturally occurring nutrients.  If the product you’re using is labeled organic -- GREAT!  However, compared to chemical fertilizers organic fertilizers contain relatively low concentrations of the actual nutrients but they perform important functions which chemical fertilizers do not.  Such as, they increase the organic content which consequently improves the water-holding capacity of the soil.

Organic fertilizers also improve the physical structure of the soil which allows for more air to get to the roots.  Plus they add more fungal and bacterial activity which makes other nutrients more available to the plant.

However, with all great things there are disadvantages as well.  I always say when using organic fertilizers (or organic insecticides) you need to “start early and stay late.”  Since you don’t get the punch of instant gratification as you would with a synthetic application, that is immediately available to the plant, you need to start an organic fertilizer almost before it’s needed so it has time to get to the roots and start it’s magic.  It’s just that organic fertilizers take time to break down to make their nutrients available to the plants.

Chemical fertilizers usually cost less, have a rapid solubility (meaning it gets to the “root” of the problem quickly) but you must be more cautious as more doesn’t always mean better in this case.  Too much fertilizer can burn up a plants root system and kill it more quickly than if it had not received any food at all.

If you’re not fertilizing your plants on a regular basis you could be depriving them of essential nutrients they need to perform their best.  Watering and sunlight are essential but those two things cannot provide everything your plant needs, especially if it’s in a container or hanging basket.

So tonight after you’ve grilled out your dinner why not give your plants some food too!   If plants could text they might just say THX!

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