Wednesday, September 14, 2011

Fertilizer! Magic Potion or toxic formula?

A few years ago, during an online search for something garden related I came across some very helpful information published by Mike McGroarty. At that time I signed up to receive his newsletter by email. Since then, for two reasons I've read each and every newsletter sent by Mike. The first reason is because they are manageable, arriving once a month or so if that often. And second, the information he provides is relevant and usable. Lately, as I've been mentally preparing for the change in seasons and with a lot of new plants in the ground this year, I've had doubts and uncertainty about fertilizing during the fall season. I was glad to see Mike's newsletter on Fertilizer arrive in my inbox just a few days ago:

Fertilizer!  Magic Potion or toxic formula?

I just came in from sitting on the front porch and I was admiring the large bed of Impatiens that Pam and I planted under and around the willow tree.  What a blast of color!

Then I thought about what I feed them.

But first, let's do the fertilizer crash course.  On a bag of fertilizer you will see three numbers like 12-12-12 or 18-6-4 or 5-36-5.  Here's what the numbers mean and  what they mean to you as a gardener.

The first number is the percentage of nitrogen in that particular bag of fertilizer.  Plants need and love nitrogen, but like banana splits, too much of a good thing is not a good thing.  So you have to make sure you are not putting too much nitrogen on any particular plant.

By the way, I like Banana Splits.  Can you tell?

The second or middle number on a bag of fertilizer is phosphorous.  Phosphorous is like an under the hood tune up for plants.  Phosphorous plays an important role by helping the plant absorb and use the nitrogen and other nutrients that a plant needs from the soil in order to be healthy and happy. 

Phosphorous really aids in the photosynthesis process and essentially makes and keeps the plant healthy.  Which means the plant will produce more flowers and fruit.  So basically, it takes the correct amount of phosphorous for plants to flower beautifully.

The third or last number on the bag of fertilizer is the percentage of Potassium in the fertilizer.  Also called potash.  Potassium gives plants stamina because it helps plants absorb and use water.  Usually there is plenty of potassium in the soil, but much of it is not in a form that plants can absorb.  The potassium in a bag of fertilizer is water soluble and easily absorbed by plants. Potassium helps plants survive drought conditions because
it helps the plant use water more efficiently.

So what does all that mean?  That means that you have to use the correct fertilizer for the particular plant you are fertilizing.  However, the fertilizer companies have made this easy for us because a lawn fertilizer has a very high amount of nitrogen because your grass grows a lot more than typical plants and grass needs and will use more nitrogen.

A garden fertilizer might have a formulation of 12-12-12 or 14-14-14.  You can use either one, don't get too caught up in the details.  But a garden fertilizer is meant to be applied to your garden before you plant and it releases those elements very quickly upon  application. It's good for a bare garden, but not so good for established plants in your landscape.  Unless used very sparingly.

Fertilizer companies make fertilizers for things like hanging baskets that are really high in phosphorous to help the plants make lots and lots of flowers.

What I use on the flowers in my beds is a product called Osmocote.  Osmocote has a lot of different formulations but what I often use is the 14-14-14.


Don't confuse Osmocote 14-14-14 with a garden fertilizer that says 14-14-14 on the label. 

Osmocote is a coated fertilizer that is engineered to release it's formula very slowly over a period of months. Unlike a garden fertilizer that releases fully in a matter of days.  Some Osmocote releases over 3-4 months. Some of the formulations take as long as 8 or 9 months to release.

I like the Osmocote 14-14-14 that releases over 3 to 4 months for my flower beds because is just sprinkle it over the bed after I plant my flowers and let it slowly feed the flowers all summer long.

What about things like Miracle-Gro, do they work? 

Yes, Miracle-Gro is a good product.  The liquid formula releases very, very quickly but is safe when used as recommended.  It's a quick release, but safer form of nitrogen.  So even if you have fertilized your flowers with Osmocote slow release granular fertilizer, you won't hurt a thing by giving them a little Miracle-Gro along the way.

Another brand name that I've used successfully on my flowers is Jack's Classic Plant Food, formerly known as Peters liquid fertilizer.

Okay!  That's a lot but I hope you find it informative and useful.
 Here's Mike in 2000 on the cover of Mother Earth News:

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  1. As I try to get more from my garden, I'm trying to figure out what is best to use. (I do use some compost, but don't make enough for the entire place!) Good information.

  2. Thanks so much for explaining this! I have the crappiest dirt. You could dig anywhere in my yard and use it to make a clay pot. Cracks everywhere. BTW, I live a stone's throw away from the Scott's Company. I have a friend who does their package design. Go to their website often as they give away samples and good coupons.

    Take care,

    P.S. Want some chicken poo? In low concentrations, it is great. I should compost, but I should do a lot of things...