Every day, we're bombarded by news reports and TV commercials stressing good nutrition. Eat right, stay away from fat and sugars, blah, blah, blah. The way I see it, we need to make the same push for plant nutrition, too.
WHY FEED PLANTS?
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! As Master Gardeners, we are often asked: "What is wrong with my plant? It looks sick?" Many times it is due to lack of nutrition. One nice lady asked: "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. In short, Mother Nature has a HUGE compost bin. In our yards we clean, primp, rake, and remove all of that food, and even more so in our container plants. THAT is why we must feed our plants.
WHAT DO I FEED THEM?
Let's first talk about the number combos on the fertilzer packages. If you look at a bag of plant food, you will see three digits, and they come in all kinds of different combinations. I use 5-2-6, for example, as this is an ideal balance for citrus. The 5 is the amount of nitrogen in the product. Nitrogen is the primary component of proteins and a part of every living cell. This nutrient is usually more responsible for increasing plant growth than any other, as long as it is used within reason and in conjunction with other nutrients. Nitrogen moves very freely through the soil and is literally washed out every time you water or it rains, especially in a container. Even in the ground, nitrogen can be depleted and needs to be replaced. Citrus are heavy nitrogen feeders. Look at the two pictures below with the light green leaves, these trees somehow got missed on a couple of feedings.
The second number (2 in my example) is phosphorus, which plays a role in photosynthesis, respiration, energy storage and transfer, cell division, and cell enlargement. We don't need much of this here in Charleston, at least for plants growing in the ground. There once were phosphate mines here, hence road names like Ashley Phosphate.
The third number (6 in my example) is Potassium, also a vital nutrient for plant growth processes. It is also vital to photosynthesis and helps regulate water in plants. It helps them overcome drought stress, increases disease resistance, and improves winter hardiness.
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 nutrients, the order is easy. The nutrients are alphabetical.
One last note: Always have your soil tested before making any major adjustments.
HOW OFTEN DO I FEED THEM?
My go to fertlizer is Citrus-Tone made by Espoma. I discovered this stuff about three years ago and I swear by it now. For in-ground trees, I start around Valentines Day and feed every six to eight weeks, stopping about Labor Day. The reason you stop around Labor Day is because that allows the new growth to harden off before the Winter sets in. Containers that are being protected during the winter, I feed all year round.
Lets say you can't find Citrus-Tone for whatever reason. The very next best thing is Miracle-Gro for Acid Loving Plants (formally called Miracid for you longtime gardeners). I use it every two to four weeks on my container-grown and in-ground citrus trees, same time table as above. It depends a lot on your soil type. Sandy soil will need more fertilizing than clay.
I give them a nice shower of Fish Emulsion about once a month or so. Stinky, but effective.
WHAT ABOUT SLOW-RELEASE FERTILIZERS?
This is a question I get quite often. They are okay to use as a supplement, but in my opinion, they release the food too slowly, especially in containers. I mentioned earlier that citrus are heavy nitrogen feeders, so these tend to simply not release quickly enough. I also have some opinions about citrus fertilizers that look like fish gravel and the Citrus Tree Spikes. Suffice it to say, I do NOT like them and dissuade anybody I talk to from using them. If you really want to know why, please feel free to ask. Due to space limitations I will not get into that here.
WHAT ABOUT WATERING?
The average quote is “one inch of water per week”. I hate that quote. There are so many variables. Sandy soil will dry out MUCH faster than clay. A large tree will need lots more water than a small seedling. In containers, I tell people to keep the soil the consistency of a wrung-out dish sponge (I know most people use dishwashers now, but you get the idea). If the leaves start to curl, it has gone too long without water. You can see the picture below that I purposely let get too dry for illustration. The best tool to check for moisture is your finger. Stick it into the soil about one inch deep, if dry, water.
DOES THIS WORK?
Think so. I had the USDA from Florida and the Department of Plant Industries out to inspect my plants a couple of years ago, after citrus greening was discovered in Charleston County. The gentleman from the USDA said that he sees LOTS of Citrus trees on a daily basis, but mine looked exceptionally good for being so far North and in containers. I took this as about as good an honor as I can get.
Rule of thumb? If you feed your citrus, they in turn will feed you! As always, feel free to contact me with your questions.