The How, When, What and Why to Fertilizing Plants

Put your plants on a nutritional diet by fertilizing. Get all your questions answered here and keep them happy! And grow your own green thumb!

By: Lively Root
July 9, 2021
The How, When, What and Why to Fertilizing Plants
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Put your plant on a diet! That's right. They need nutrition too. Adding the right amount of the big three, Nitrogen (N), Phosphorus (P), and Potassium(K), along with other micronutrients, can take your plant from sad to happy, happy, happy. Since your plants are not outdoors soaking up the nutrients in the earth and the earthworms are not leaving rich castings that fertilize, we gotta give a little help to our plant friends when they're in containers! 

The Why of Fertilizing Plants

Let's first talk about what those numbers mean on the fertilizer bottle or bag. 



The numbers are a set of three. They stand for the big three, as mentioned before—Nitrogen, Phosphorus, and Potassium. To distinguish what each one does for your plant, memorize the little saying: “Up, Down, All around.”


The first number is Nitrogen, and that's what is referred to as the UP part of the plant. The nitrogen majors on the leaf growth. So, if you have a leafy plant like a fiddle leaf fig or alocasia plant, your nitrogen number may have a higher number if you get specialized fertilizers. Nitrogen is what keeps your plant overall healthy. It enables the plant to synthesize the sunlight by which photosynthesis occurs to make food for the plant. An example of this is when the grass turns greener after a spring thunderstorm. Nitrogen is a part of the chlorophyll molecule, so it stands to reason, your plants will be healthier with it. 

The next one is Phosphorus. This is the Down part of the saying or better known as the roots of the plant. The roots are going to carry water and nutrients in the soil to the plant. And healthy roots stabilize the plant and also help fight diseases. Phosphorus also helps produce seeds and fruit, so if you were growing an edible fruit, you'd want more Phosphorus in the fertilizer formula. 

The next one is Potassium, and it helps develop the flowers and fruits, which insinuates the "All Around" part of the plant.

Potassium also helps resist pests, uses water better, and fights off disease. Symptoms of potassium deficiency would appear in the lower part of the plant. The leaves might turn yellow at the leaf margins or edges. This symptom could be from overfeeding, too. We recommend taking notes when you fertilize and with what and how much and keep it on your digital calendar! 

When is the Best Time to Fertilize my Indoor Plants?

Outdoor plants begin to "wake up," so to speak, in the spring when daylight hours are longer, and the soil starts to warm up. That goes for indoor plants as well. Your plants can feel the change from the light changes inside the house if you have natural light. So, from late March to early April, it's safe to start fertilizing your indoor plants through September. 

How to Mix the Fertilizer  

For most indoor plants, you can put them on a monthly rotation to fertilize. Plants with synthetic soils or soil mix need to be fertilized at 1/2 strength. Mix a 1/4-1/2 tsp of our Foliage-Pro in a gallon of water, and stir it well. Use it just like you're watering your plants. Apply it until the water is dripping out of the drainage holes of your planter. Let completely drain, then place back into your decorator pots if you keep the plant in a grower pot. 


Foliar Feeding

Foliar feeding is also an option for your plants. Typically, you will want to dilute your fertilizer more for foliar applications than you would for the soil to avoid burning the leaves. Test a spot on one leaf before applying it to the whole plant and wait a week to see the results. You can apply our Foliage-Pro every 2 to 4 weeks and follow the labels' directions for either soil application or foliar spraying. Mix it up in a gallon size container, then pour some into a spray bottle and apply. 

Foliar fertilize your plants in the early morning so the air can dry the leaves during the day to prevent mold or fungus. If a leaf stays wet too long, it can lead to fungus issues. This goes for outside plants as well. Spray feeding would be a supplement to the fertilizers you are already applying to the soil.


How Do I Fertilize my Outdoor Plants?

As long as there isn't snow on the ground and your outdoor plants are breaking dormancy, you can fertilize in the spring. Let's say, when you start seeing buds on the trees and shrubs, you can fertilize outside too. We recommend using John and Bob's Optimize Plus organic fertilizer that's a soil conditioner. 

If your soil is in poor health or has been tilled a lot or stripped of nutrients, this is what you need. It has beneficial microbes and adds organic calcium and iron that will help balance the soil's pH. If you have hard or clay soil, this is an excellent conditioner. It releases each time the plant is watered. This soil conditioner will increase the fertility and vitality of the plants. And one cup will treat 180 sq ft, so it is very concentrated. 

You can apply 6 T. to a small plant or shrub you're planting outdoors. Apply this any time of year between the spring and fall. To apply fertilizer and conditioners, scratch the surface around the plant's dripline to hit the root area. 

The "dripline" is a horticulture term that means the spot where rain would "drip off the plant" or the widest part that the limbs reach around the plant. Now, you'll want to read the instructions carefully to apply the right amount for your plant. Evenly spread the fertilizer and conditioner around the dripline's circumference. 


Then, cover up the ingredients with the soil you scratched and water it in with a light shower setting on your nozzle to let it evenly soak in. 

You don't want to spray the water hard to hurry up this process, or you could waste your fertilizers and amendments by washing it away too fast before it soaks in. You also don't want to splash potential fungus or bacteria upon the leaves of your plant either with the hard and fast method of watering. Just take it slow and steady, and don't be in a hurry when you're gardening. Pour yourself a glass of sweet tea or take a glass of wine out with you while you water the fertilizer and plants. 

Schedule adding amendments and fertilizer about the same time that you’re applying mulch in the spring or else in late March when the days start getting longer. 

Signs of Under or Overfeeding Your Plants

How do you know if you're overfeeding or underfeeding your plants? 

Too much fertilizer can cause leaf edges to turn brown if the growing conditions are good in every other way. It can also cause the lower leaves to drop on your plant prematurely. Now, this is a natural occurrence occasionally but if you have a new plant and all of a sudden you see leaf drop, check how much fertilizer you're giving it. If you discover it's reacting to too much fertilizer, you can flush your plant with water by giving it an excessive drink and let it drain thoroughly. Water it, then water again to wash away the salts. If that isn't enough, you might want to repot it in fresh soil to help it recover. 

Underfeeding your plants will produce pale leaves, fewer or no flowers at all. 

If your plants are on a monthly diet, then set your calendar on your phone to remind you to fertilize!


When Not to Fertilize--The Dormancy Period

When the days start getting shorter, the plant is going to go into dormancy. This means they're going to have a resting period where they don't grow as much. Shorter days and cooler temperatures induce dormancy. Typically, during this time, they have an absence of new growth, and you may have some yellowing of leaves that fall off. If you do, make sure you're not overwatering it at this point. While they're resting, they're not getting as much light, as usual, hence the need for water reduction too. Remember always to use your 3 in 1 meter to check moisture levels before adding water! 

And here's another note. Tuberous and bulbous plants like your caladiums and amaryllis will die back to the ground while they rest, just like daffodils and tulips outside. 

Finishing Touches

Now, you better understand what the NPK means and a little saying to remind you ("Up, Down and All Around"). Plus, you know when and how to fertilize your plant babies. Now, please do one more thing for yourself! Keep a record on the 1st day you start fertilizing in the spring and record how tall and wide your plant is, and then measure in September when you stop fertilizing and see how much it has grown! That will be fun to see the difference from year to year for each plant! Let us know how much your plants have grown in one season!