Fertilizer: Recipes for Great Growing

People often think of fertilizer as plant food, but this is not technically correct. Instead, fertilizer is a combination of ingredients that are necessary in order for a plant to manufacture food internally. This, in mind, I’d like to help you with some basic information on fertilizer ingredients, ratios, and implementation plans. It’s really not as complicated as it seems.

Basic fertilizer contains three primary ingredients: nitrogen (N), phosphorous (P), and potash or potassium (K). Then, in some fertilizers, various trace elements are added, such as manganese, magnesium, boron, copper, and others. Personally, I find the proliferation of so many different combinations and analyses of fertilizer a bit confusing. It helps, though, to understand that fertilizers are mixed in ratios of one nutrient to another. Generally speaking, nitrogen is the first number listed and is used primarily to aid vegetative growth while phosphorous and potassium are assumed to be more important to root growth and flower and fruit development. Therefore, your lawn may be better off with a fertilizer containing four parts nitrogen to one par each of phosphorous and potassium – generally written 4N-2P-2K mixture. Annuals, on the other hand, may thrive and flower better on a 1N-2P-2K mixture. Of courser, there are combinations in between and also unlimited number of ways to integrate trace elements. These are just general guidelines, and it is important to realize that each manufacturer, perhaps rightly, thinks his or her analysis is best for each kind of plant. As always, read the labels and check with your garden center for specific plant recommendations as certain plants occasionally require a more specific analysis of fertilizer.

There are two major ways to implement fertilizer: namely, you can use dry materials or liquid. You can apply the liquid types with a hose and an attached apparatus, or mixing in a watering can, or by professionals with more powerful equipment (especially for use on trees). Either way, this method can be especially helpful to plants that have need of a readily available, quick uptake of fertilizer. Many water solubles also have extended release capacity. Much fertilization is done with dry, granular material, though and is broadcast on the surface of non-grassy beds or installed in drilled holes in the ground in the lawn area Your choice should be based on your preference and the needs of your plants. No matter what method you decide on, be sure to follow the rate charts very closely for quantity recommendations. Remember that if one aspirin is good; four are not better and may be very dangerous at rates above the recommendation. Too much of a good thing is just that – too much.

As for how often you should fertilize, it varies greatly from plant type to plant type and growing conditions and soil type, etc. For instance, a healthy shade tree needs to be fertilized only once every two to four years. Annuals and roses, though, may need a 1N-2P-2K (or similar) ratio as often as every three weeks. Again, see the package recommendations for frequency. As a general
statement, it’s best to fertilize regularly and avoid a feast or famine situation.

I can’t emphasize enough how important fertilization is this year. Due to the alternate lack and surplus of rain over the past few years and the stress it has caused plants, we need to take action now to save and maintain plants that may otherwise be lost. If you have never fertilized before, this is definitely the year to do it. We have had a wonderful spring of bloom and now we need to encourage a good summer of growth. One final note - Since fertilizers add elements to the soil to aid plants, it is important to know the nature of your soil. For this reason, a bonified laboratory soil test is advisable. If you are interested in this, your OSU Extension Agent or garden center can help direct you. The fee is nominal and the benefits are many.