Feeding Plants with Fertilizer
Wanting to give your plants a little boost? Wanting to make them produce larger, more colorful blooms? Wanting them to leaf out and spread quickly to act as a ground cover or fill that empty patch in the garden? Wanting them to produce more fruits? Obviously, what is called for is fertilizer, but how do you know which fertilizer will give you the results that you are hoping for? Here are a few tips to help you choose the plant fertilizer that is right for the plants in your garden that will produce the results that you are looking for.
Before You Start
The texture and acidity (pH level) of the soil determines the availability of nutrients that your plants can actually use, as well as effecting the movement of water and air that plants need to thrive. It is a good idea to have your soil tested, preferably before you plant, as different plants have different nutrient requirements. It is also important to know your soils pH before fertilizing, so that nutrients intended for your plants won’t leach out of the soil before they can ever reach them. Testing your soil is a fairly simple process that can be done easily with a home testing kit or if you prefer, you can simply send a soil sample to your local county or state agricultural agency. The nice thing about having your county extension service do the testing is that they will usually send recommendations for fertilizer and soil amendments with your results. (Components and Uses)
Read the Package
The first thing that you want to do when shopping for a fertilizer is to read the package. Most fertilizers not only tell you which plants they are best used on, but they also tell you what ingredients they contain, which tells you a lot about what kind of results they will produce. Somewhere on the front of the box or bag you will see three numbers, such as 10-20-10. These are the magic numbers of fertilizer, because they tell you if that particular fertilizer will do the job that you have planned. These three numbers give you the ratio of the three main ingredients necessary to the health of your plants.
If you are trying for an end result of greener, leafier, fuller leaves in forage plants or higher yields in fruiting plants, then you will want to pay close attention to the first number, which is the nitrogen content of the fertilizer. Nitrogen promotes leaf growth, as well as increasing seeds and fruits. If what you desire is a strong root system or you want to have big, beautiful blooms, then the second number will be the most significant to you. This number indicates the amount of phosphorus in the fertilizer. Phosphorous promotes rapid growth, particularly in blooms and root systems. If what you are aiming for are big, strong plants with quality fruits, you might want to get a fertilizer that’s a bit higher on that third number, which indicates the potassium content. Potassium is absorbed in larger amounts than any other nutrient except nitrogen, and helps in building protein, aides the photosynthesis process and helps to fight disease.
So, if you have a bag of fertilizer with the magic 10-20-10 on it, you know that that particular fertilizer contains 10 lbs. of nitrogen, 20 lbs. of phosphorus, and 10 lbs. of potassium per every 100 lbs. A fertilizer that contains all three of these nutrients, (regardless of the ratios), is considered to be a complete fertilizer, because these are the primary nutrients required for plant growth.
Fertilizers also contain secondary nutrients, such as calcium, sulfur and magnesium, and micro nutrients, such as manganese, boron, copper, molybdenum, cobalt and zinc. Calcium is an essential part of plant cell structure and strengthens plants. Magnesium is important to photosynthesis and activates enzymes that encourage growth. Sulfur produces protein, improves seed production and root growth, and helps with cold resistance. Copper plays a part in carbohydrate and nitrogen metabolism, and provides strong plant walls and prevents wilting.
Also contained in fertilizers, are micronutrients, (which are only needed in minute quantities), which aide the growth rate of the plant, as well. Boron, copper, chloride, iron, manganese, molybdenum and zinc would all be included in this category. A glance at the ingredients listed on the package will tell you how much of each nutrient contained in a particular fertilizer.
Identifying Which Nutrients Your Plants Need
Occasionally, you may desire to achieve some very specific results. You may think about adding a desired nutrient directly to the soil. However, more is not always better and the best thing to do is to get a good, all around fertilizer that contains all three of these ingredients to produce all around strong, healthy plants. To determine what nutrients your plants are lacking, look for tell tale signs on the plants themselves. When older leaves begin to loose their green color and turn yellow, while younger leaves are unaffected may indicate a nitrogen deficiency. Purplish or bronze colored leaves would lead to a diagnosis of phosphorous deficiency, while leaves with yellow, translucent spots and browning leaf margins would indicate that the plant is lacking in potassium. In any of these cases, adding any fertilizer that contains the three magic numbers, (nitrogen, phosphorous and potassium), should do the trick.
Younger leaves that loose their color, becoming nearly white in some cases, while veins remain green, would indicate the presence of an iron deficiency. Young leaves that are pale or grayish, with yellowing between the veins could mean that your plant needs more zinc. If the root and shoot tips are thickened and begin to die off, new shoots are withered or dead, leaves have tip burn, or the whole plant seems stunted, trying fertilizer that is rich in calcium may be what is called for. Yellowing, thin leaves that wither easily, stunted growth (new shoots do not open) or dieback of stems and twigs on a plant that is pale green overall, could indicate a copper deficiency. Yellow molted areas on leaves would indicate a need for manganese, while yellowing of the spaces between leaf veins shows that magnesium may be lacking. If the whole plant is stunted and pale, with yellowing leaves that have pale veins, sulfur may be what is needed, and if growing points die back and young leaves are distorted, forming unnatural rosettes, some added boron might help. Yellow leaves that are distorted and narrow could indicate a lack of molybdenum.
A full inspection of the plant is necessary to determine that the problem is not caused by insects, disease or improper environmental conditions, which may cause similar symptoms. Plants not receiving balanced nutrition can become more susceptible to disease causing organisms, insects or environmental extremes. Usually, if insects are responsible for the poor condition of a plant evidence of insect activity, such as damaged leaves, eggs on the undersides of the leaves, or the insects themselves will be visible. Make sure there are no fuzzy threads (hyphea), or fruits with rotting flesh, caused by fungus present on the plant. Also check for burnt leaves that would indicate too much sun, soil moisture to be sure the plant is not over or under watered, and make sure it is located where temperatures are accommodating to plant growth. Any of these factors can cause symptoms that are similar to those of nutrient deficiencies, so care should be taken to rule out other problems before these other problems. (O’Callagan) While fertilizing is generally good for your plants, other problems need to be identified and treated.
Excess Nutrients Can Cause Problems
Just as important as getting the right fertilizer for you plants, is making sure that you follow the directions on the package when using a commercial fertilizer. Soils that are too high in phosphorous or iron can cause a deficiency in copper, which is required for strong cell walls and prevents wilting. Excesses of some mineral nutrients such as potassium, calcium, nitrate-nitrogen, and magnesium may cause deficiencies in other nutrients. Excesses of other mineral nutrients such as boron, manganese, ammonium nitrogen, copper and zinc can result in toxicity. (Hershey)
Note: While lime can raise pH to the desired 6.0 to 6.5 and helps promote air and water movement when applied to acidic soils, large amounts of calcium and magnesium are also deposited into the soil, which can be good for calcium and magnesium loving plants, but can cause deficiencies in others. Chemical fertilizers applied in a concentration that is too high may damage roots or cause a salinity problem, resulting in plants not being able to get enough water. If this is a worry, stick with organic fertilizers to lessen the risk of plant damage.
Homemade or Organic Fertilizers
- Organic fertilizers that are nitrogen rich include bat guano, blood meal, fish meal and soybean meal.
- Organic fertilizers that are high in phosphorous are bone meal, colloidal phosphorous and rock phosphate.
- Organic fertilizers that are rich in potassium granite dust, greensand and ground kelp.
- In nature, plants often get the three main nutrients, (the three magic numbers), from decaying plant matter lying on the ground. Decomposing plant matter can also add significant sulfur content to the soil. Many feel that it is unsightly to leave last years leaves and other plant debris laying in the yard and it makes the perfect place for slugs and other pesky creatures that could do damage to your plants to hide. An alternative to this would be to build a compost pile and then start with good soil that is rich in nutrients and organic material to begin with. Recycling tree leaves and grass clippings through composting is a great way to add primary, secondary and micronutrients to your soil. For instructions on how to make a compost: http://www.ehow.com/how_3541_begin-compost-pile.html
- Sprinkling used coffee grounds or tea leaves around the base of the plant before watering to produce a slow release of nitrogen into the soil, or dilute them in water to create a gentle spray-on fertilizer that is fast acting. (Coffee and Gardening)
- Magnesium loving plants, such as peppers, potatoes, tomatoes or roses will love a homemade fertilizer made from 1 tablespoon Epsom Salt with a gallon of water.
- In Backwoods Home Magazine: practical ideas for self-reliant living, Christopher and Delores Lynn Nyerges tell how to make your own liquid fertilizer out of seaweed (or kelp). They also suggest using fish emulsion, earthworm compost, eggshells, coffee grounds and rabbit droppings. See “You can make your own fertilizers”: http://www.backwoodshome.com/articles/nyerges44.html
- Another inexpensive fertilizer can be made from all those pesky weeds that you pull and then don’t know what to do with them. See “How to Make Own Organic Fertilizer”:
“Components and Uses of Fertilizers in the Garden”. The Garden Helper. September 12, 1999. http://www.thegardenhelper.com/fertilizer.html
“Coffee and Gardening”. Sustainable Enterprises. http://www.sustainableenterprises.com/Business/coffeefert.htm
Hershey, David. “Re: How do the amounts of fertilizer affect plant growth?”. MadSci Network: Botany. April 17, 2002.
“Plant Nutrients”. North Carolina State Agricultural Office. http://www.agr.state.nc.us/cyber/kidswrld/plant/nutrient.htm
O’Callagan, Angela, Ph.D. “Recognizing Plant Nutrient Deficiencies”. University of Nevada, Cooperative Extension: Bringing the University to You. Fact Sheet 02-65. www.unce.unr.edu/publications/files/ho/2002/fs0265.pdf