Soluble Fertilizers Can Be Useful to Gardeners

Fertilizers are now available in many forms. So many in fact, that making choices can be confusing. There are dry granular, pelletized, slow release, controlled release and soluble forms. Some are organic, others are inorganic and there are some that are a combination of both.

So which kind is best? Plants really don’t care as long as they are getting the right amount of nutrients, in the right concentration and at the right time.

Soluble, or the so called “liquid fertilizers” for example, have become popular with many gardeners over the past few years. Though I don’t recommend them for fertilizing everything in the landscape, they can be useful in growing flowers, herbs, vegetables and potted plants.

There are several brands of quality soluble fertilizers on the market. Most are offered with convenience in mind. They are usually attractively packaged, and frequently include a handy measuring spoon to aid in accurately mixing solutions.

All soluble fertilizers are not the same. They come in many formulations, with varying amounts of nitrogen, phosphorus and potassium. Some include trace, or minor elements, and some do not.

Sandy, Gulf Coast soils are peculiar in that they retain phosphorus while nitrogen and potassium don’t remain for very long. With this fact in mind, choose products that are low in the middle number, which is phosphorus. Look for a ratio of 3-1-3 or 3-1-2, which includes 15-5-15, 20-5-15 or similar formulations with a low middle number.

Soil that is low in organic matter and porous potting mixes might also benefit from using a soluble fertilizer that also includes trace minerals. Some products have them and some don’t, so read some labels while in the store. In addition to the major elements, look for a list that includes iron, sulfur, manganese and other minors.

Leaf Feeding vs. Soil Application

Soluble fertilizers are used for both foliar feeding and for application to the soil around plants. In most cases, application to the soil within the plant’s root zone is far more effective and long lasting than foliar feeding.

The purpose of plant leaves is to use sunlight and convert it to energy for the plant, not absorb fertilizer. Roots on the other hand, are capable of taking up nutrients and translocating them throughout the plant.

It’s true that foliar feeding can sometimes quickly green up yellow plants. Amazing results are often seen when a soluble fertilizer containing iron is sprayed on plants that are deficient in that mineral. Though recovery might be rapid, it is usually temporary.

Some soluble fertilizers have two different mixing rates, depending upon the application method. A much weaker solution is used for foliar feeding because there is more danger of leaf burn when compared to concentrations used for soil application.

Question of the Week: I am growing pepper plants indoors and they are blooming, but the flowers produce no fruit. What can I do to make them bear?

Answer: Move them to an area outdoors that receives full sunlight. Peppers have several requirements that won’t be satisfied inside of a house. In addition to the lack of sufficient natural light, peppers are air pollinated. They need the shaking and swaying supplied by wind. Sufficient fluctuation in day and night temperatures are not found indoors either.