The past week or so I have been extremely busy as a Master Gardener. I have been working the Home and Garden Show, doing a lecture or two, and working our information booth out at the Coastal Carolina Fair. At every single event I got asked "What is wrong with my plant?"
I think we need to start having those nutrition commercials for plants also. It is absolutely amazing to me the amount of people that think they know how to grow plants, but have no idea that they need to be fed!
Okay, to be fair, I was asked by one nice lady....Why do I need to feed my plants? Nobody is feeding the plants in the forest.
I told her she was partially right. Mother Nature was feeding them. She had a very perplexed look on her face after that.
We have basically screwed with the natural order of things. In the forest, leaves drop off every Autumn. They fall to the ground and decompose. Nobody rakes them up into a nice neat pile and hauls them away. That is food for the plants for next year. Along with animal droppings, worm castings, other plants that die, and all kinds of other micro-organisms. That is how Mother Nature feeds her plants. In short, she has a HUGE compost bin. In our yards we clean, primp, rake, and remove all of that food. It is even worst in our container plants. THAT is why we must feed our plants. She walked away with a brand new look on feeding.
If you look at a bag of plant food, you will see three numbers. There are all kinds of combinations, I will use 5-1-3. The 5 is the amount of Nitrogen in this product.
Nitrogen is the primary component of proteins and is a part of every living cell. This nutrient is usually more responsible for increasing plant growth than any other nutrient, as long as it is used within reason and in conjunction with other nutrients. Shortages can cause slow growth, reduced leaf size, yellowing, short branches, premature Fall color and leaf drop, and increases the likelihood of some diseases. An over abundance can cause excessive shoot and foliage growth, reduced root growth, and increased susceptibility to environmental stresses and some other plant diseases.
This what a Nitrogen deficiency can look like:
Notice the yellow leaves compared to everything around it? This is a Citrus tree that some how or another kept getting missed when it came to feeding time. Everything else around it looks fine. Nitrogen is a nutrient that moves very freely through the soil and is literally washed out every time you water or it rains, especially in a container such as this one. Even in the ground, Nitrogen can be depleted and needs to be replaced.
The second number (1 in my example) is Phosphorus. This nutrient plays a role in photosynthesis, respiration, energy storage and transfer, cell division, and cell enlargement.
Though less common than Nitrogen deficiency, Phosphorus shortages can look like this:
Purple veins may appear on the leaves or the leaves may take on a purplish color. It will also produce stunted growth and small thin stems. Like I mentioned, it is much less common a problem. If you have ever applied any fertilizer, the chances are good that the Phosphorus is still there. It does not move through the soil hardly at all.
The third number, (3 in my example) is Potassium. I should pause here a second and give you a tiny memory trick. Do you have trouble trying to figure out what order the numbers are in on the bag? As long as you can remember the three nutrients, Nitrogen, Phosphorus and Potassium are the three numbers listed on a fertilizer bag, it is always listed in alphabetical order.
Now, back to Potassium deficiency. It too is involved in many of the plants growth processes. It is also vital to photosynthesis and helps regulate water in plants. Potassium fertilization helps plants overcome drought stress, increases disease resistance, and improves Winter hardiness.
It can look like this:
Typical symptoms of Potassium deficiency in plants include brown scorching and curling of leaf tips. The symptoms generally first appear on older leaves. Potassium can move through the soil fairly quickly, faster than Phosphorus, but not as fast as Nitrogen.
That is a very quick idea of what are called the Macro-Nutrients. These are what a plant needs the most of.
There is also a list of Micro-Nutrients. These are needed by the plant, but in much lesser amounts.
This list includes:
Boron. Believed to be involved in carbohydrate transport in plants; it also assists in metabolic regulation. Boron deficiency will often result in bud dieback.
Chlorine. Necessary for osmosis and ionic balance; it also plays a role in photosynthesis.
Copper. A component of some enzymes and of vitamin A. Symptoms of copper deficiency include browning of leaf tips and chlorosis (leaf yellowing).
Iron. Essential for chlorophyll synthesis, which is often why an iron deficiency also results in chlorosis.
Manganese. Activates some important enzymes involved in chlorophyll formation. Manganese deficient plants can develop chlorosis between the veins of its leaves. The availability of manganese is partially dependent on soil pH.
Molybdenum. Essential to plant health. Molybdenum is used by plants to reduce nitrates into usable forms. Some plants use it for nitrogen fixation, thus it may need to be added to some soils before seeding legumes (Beans and Peas).
Zinc. This also participates in chlorophyll formation, and activates many enzymes. Symptoms of zinc deficiency include chlorosis and stunted growth.
So, as you can see, many nutrients rely on each other, or deficiencies can mimic each other.
There is not much need to worry about the Micro-nutrients, most good fertilizers already have them.
Which brings me to my next point. Types of fertilizers.
You should ALWAYS get your soil tested by your local extension office before applying any fertilizer. It could actually save you some money, time, and headaches in the end.
With that being said, the shear number of fertilizers on the market can be overwhelming! There are granules, water soluable, slow release, quick release, natural, and on and on. In a way I can see why people don't feed their plants, they have no idea what to use!!
Let me break down a few of the more common ones.
Slow release fertilizer. It is exactly what it sounds like. They release nutrients at a rate that makes them available to plants over a long period. They are applied less often and many believe they are better for the environment because they have less chance of leaching into the water supply. While I am on this topic, please do not use fertilizer spikes. If you want the whole story as to why not, I can give it to you. Suffice to say, they are just bad news.
Water Soluable. Again, exactly what it sounds like. This fertilizer is mixed with water at a specified rate. This type of fertilizer needs to be applied more often, but it is available to the plant much more quickly.
Natural Fertilizers. When it comes to the naturals, there is often a lot of quess work involved. Most natural materials are far less predictable in nutrient content, nutrient release, and nutrient efficiency than commercial grade fertilizers. Before most natural fertilizers can be absorbed by plants, they have to be broken down to an inorganic form by soil microorganisms through a decaying process called mineralization. This process is affected by moisture, temperature, and the microbial species and populations in the soil. Some examples of Natural fertilizers include, Blood Meal, Sewer Sludge, Animal Manures, Fish Emulsion and Cottonseed Meal.
The advantages and disadvantages of natural and synthetic fertilizers relate to the consumer, not to the plant. Use what you feel comfortable with, or have had success with.
This whole article just barely scratches the surface of fertilizers. I did not even get into the effect soil pH has on fertilizers. Or "when" to fertilize the plant if it is in the ground or in a container, especially if you will be protecting the containerized plants over the Winter or anything else like that. If you have a specific question in that regard, please feel free to contact me.....TheCitrusGuy@netzero.com.
There is so much information out there and new studies are being done almost on a weekly schedule. I wanted to bring your attention to the fact that plants DO need to be fed, whether it be naturally or artificially.
I will leave you with this story, completely true!
A woman came to me with a Citrus problem. She had a Meyer Lemon that she bought two years ago. It was a nice little tree already bearing fruit. She was growing it in a pot. When she came to me, the tree had not produced any fruit the prior year and was turning yellow. After a few questions I found out she did not know it needed to be fed, and had not given it anything to eat in the two years she had owned it!! I asked her how she would feel if she had not eaten in two years!?
Please remember to feed your plants!!
Happy Growing!
Darren
