Garden Plant Fertilizer, pH and Micro-Nutrients

Plant Fertilizer

About Garden Plant Fertilizer

Confused over what garden plant fertilizer to apply to your garden, when, and how often? What do all these fertilizers do for your plants anyway? Is it that important? Is more better?

These are all common questions about one of the more confusing aspects of gardening. Fortunately, you do not need to have a degree in chemistry to grow a home garden. Nor do you need a college degree, to understand and apply basic garden fertilization concepts.

Importantly, in order to know what fertilizers to apply, you need to know how much fertilizer is currently in your soil. To find out, can take a soil test using an inexpensive Soil Tester.

Did you know? You should apply different types of garden fertilizers at different times of the growing season.

Garden Plant Fertilizer Selection Chart

Balanced Formula (10-10-10, 0r 20-20-20) – This general-purpose fertilizer is a good choice for new gardeners.

Early Season (20-20-20) – Aids in the development of leaf and root structure.

Blooming Period (5-10-5) – Promotes those beautiful flowers you are seeking.  and the flowering of vegetables.

Fruit Growth (10-10-20) – After the blooming stage, fruits and vegetables benefit from higher potassium.

Super Phosphorous (0-30-0) – Used by experienced gardeners and professional growers to promote bigger blooms.

Super Potassium (0-0-60) – Used by experienced gardeners and professional growers to get bigger fruits and vegetables. For example, this is used by growers of giant pumpkins, squash, and watermelon for competition. 

The Chemistry of Garden Plant Fertilizer

A Chemistry degree is not needed, to understand the basics of fertilizers for your garden. Most fertilizers display the three major chemicals on the packaging. It will look like this:

5 – 10 – 5

And it stands for:  Nitrogen – Phosphorous – Potassium

If you remember High School science classes, they are abbreviated as “N”, “P” and “K” respectively.

The number above the chemical represents the percentage of that chemical element in the fertilizer. Depending upon the growth stage of your plant, you should seek higher or lower levels of these chemicals.

Nitrogen Fertilizer

Apply higher concentrations of Nitrogen in the early growth stage. It provides for leaf root growth. High levels of nitrogen result in a lush, green plant. Of the three major chemicals, nitrogen can also provide the most damage, as it can burn your plants. Avoid direct contact with leaves and vines. For example, if you have ever put too much fertilizer on a section of lawn and see it burn out, you can understand the effects.

Too much nitrogen also can reduce or delay the emergence and number of flowers and fruit. If your plant seems to be thriving and is a healthy green, yet has no flowers, stop adding nitrogen for a week or two. Eventually, the plant will redirect its energy from plant growth to fruit set and development. Also, extremes of nitrogen can cause wilting (due to burning) of your plants.

Phosphorous Fertilizer

As the season moves towards the flowering and fruit set stage, switch to a formula higher in Phosphorous. Flower growers like Phosphorous to help promote big, bright blooms. 5-10-5 or 5-15-5 are common ratios. If you do not want to worry too much about what fertilizer to use, this is a good overall ratio for the entire year.

Phosphorous will promote both root growth and fruit set and development. Phosphorous is more forgiving as it does not burn your plants. It is less water-soluble, so an over-application will not do major harm to your plant.

Potassium Fertilizer

This chemical will promote fruit growth. After the fruit set, you should either switch to a high potassium fertilizer or supplement your feedings with extra potassium. Like Phosphorous, it will not burn your plants. Over application, however, along with all the other ingredients(sun, water, rich composted soil) can cause have negative effects on your plant. Take it easy early in the fruit development stage, especially if you are a new grower.

Now that you have enjoyed the science class, go out and put it to work in your garden. Remember, to avoid over applications and not to overlook the other essentials of good soil, plenty of compost, and plenty of water.

Other Chemical Fertilizers

There is a wide variety of chemicals which are essential to plant growth. This applies to any plant growth whether it be a vegetable, a tree, a flower or weeds. Just read a box of liquid fertilizer and you will see the chemicals and trace elements. Some of these are likely to be in your soil already and others are not. It all depends on what type of soil you have, whether these elements are readily soluble and whether they have been depleted through years of growing. Look at these as the “vitamins” for your plants, as that is exactly what they are. As you take regular, daily vitamins, you should also provide regular vitamins to your crop. If you are buying a name brand fertilizer, these minerals and nutrients will be included.

Liquid Garden Plant Fertilizer

Liquid Fertilizers are a popular fertilization method. Most importantly, use the proper amounts when mixing liquid fertilizers.  Spray it directly onto the leaves or pour it directly to the root system. Also, use liquid fertilizers in the water supply for drip or other underground irrigation systems. Because it is water-soluble, it is immediately absorbed into the plant’s root system to give a quick boost.

Aside from cost (and it is not that much), liquid fertilizers have almost no downside. They include all the chemicals needed for good growth. In addition, because they are in a water-soluble state, they can easily be absorbed by the plant.

One limitation is that it is often difficult to find a mixture other than the normal average which is usually something like 5-10-5. If you want to stress one chemical over the other, it is hard to find a different mixture. Secondly, because it is dissolved in water it leaches through the soil and must be frequently applied.

Another important point is you should not rely exclusively on liquid fertilizer. Nothing beats a rich garden soil supplemented with compost and manure. Gardeners should perpetually seek to improve their soil and successful ones always do.

Foliar Feeding Your Plants

Foliar feeding is the simple, but important process of feeding your plant through the leaves. Use a liquid fertilizer and spray leaves and vines. Make sure to follow the directions on the fertilizer container. Importantly, do not use too much fertilizer, and mix thoroughly. Too much fertilizer can burn the leaves. Regular weekly or more frequent applications will result in healthier, greener leaves.

After having been away on an extended trip one year, I began foliar feeding upon my return. A week later, my neighbor remarked at how green the plants had become since my return. He suggested that the plants had missed me. I agreed and did not let him in on my secret.

If you practice foliar feeding regularly, you will not see a difference as clearly as the example above. But, you will have much healthier and stronger plants all season long. And, you will add significantly to the size of your flower, fruit, or vegetable.

More on Plant Foliar Feeding

Your Garden Plant Fertilizer Strategy

Now that you are armed with a little knowledge about fertilizers, it is time to plan your strategy. Here is a basic plan and template for you to use. Adjust it for your area and conditions as well as your personal experiences and experimentation ideas.

  • Before planting, prepare a bed rich in compost, manures, and nutrients.

  • Mix general-purpose garden fertilizer into the soil before planting.

  • Apply foliar feeding once a week or more.

  • Apply dry fertilizer every two to three weeks.

  • Include liquid fertilizer in the water your feed your roots, as often as you desire.

  • Use fertilizers high in Nitrogen until flowers appear.

  • Switch to higher Phosphorous during the fruit set stage.

  • Use high Potassium fertilizers for fruit growth.

Garden TIP for Inexperienced Growers: In your first year or two, simplify your efforts and look for a balanced dry fertilizer like 5-10-5. Then apply it every two weeks and thoroughly water it in. Apply liquid fertilizer as a foliar feeding if and when you find the time and inclination. You will be rewarded for the minimal effort and can get more “experimental” in the following years.

Secrets of Other Growers

Every avid grower develops his own secret ingredients from fertilizer to the preparation of the soil. Some will share their secrets, others will not. You will need to judge and evaluate the facts from the fiction.

A friend of mine overheard a grower at the bar who had had one or two too many. The grower said his secret to giant pumpkins was adding milk to the soil. My friend had a couple of gallons of milk which were beginning to sour. So, he said “what the heck”, and applied it to the pumpkins. All he got for his efforts was a sour-smelling patch. Fact or fiction? I don’t know. But, if there is any truth to it, it is probably in the chemical composition of milk. Plants need calcium (a major element of milk) for root development. This sounds to me like the “root cause” of the growers’ secret.

Common Problem with Garden Plant Fertilizer

Most problems with fertilizers occur with new and in-experienced growers. The biggest problem with fertilizers is over-application. If you apply too little fertilizer, nothing much happens, including no burst of growth or green-up of your crop. The danger lies in over-applying.

Nitrogen in fertilizers can burn your plants, causing wilting and delaying the flowering stage. In short, take it easy, take it slow. Importantly, study the results of your fertilizer applicarions..

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