Plants Need Food Too - How To Fertilize Like a Pro

I will be offering lots more information on fertilizer during my  Houseplant Care 101 Workshops  at the  Horticulture Center of the Pacific  this fall. Stay tuned for more information!

I will be offering lots more information on fertilizer during my Houseplant Care 101 Workshops at the Horticulture Center of the Pacific this fall. Stay tuned for more information!

Often overlooked or deemed unnecessary, this integral part of plant parenthood can seem daunting, but fertilizing doesn't have to leave you cross-eyed.

Like learning a new language, learning about fertilizer can be frustrating. From words that bring back nightmares of Chem 12, to worrying about timing and measurements, to deciding between the thousands of products on the market, it's no wonder I often have people screaming at me HOW THE HELL DO I DO THIS? Well, like all tough things in life that we don't understand, let's break this baby down and build it back up...

The elements.

Like us, plants require specific elements to survive. In order for them to photosynthesize, grow and metabolize they need these 16: carbon (C), hydrogen (H), oxygen (O), nitrogen (N), phosphorous (P), potassium (K), calcium (Ca), magnesium (Mg), sulfur (S), iron (Fe), zinc (Zn), molybdenum (Mo), boron (B), copper (Cu), manganese (Mn), and chlorine (Cl). . The macronutrients, which are required in much larger amounts, are nitrogen, phosphorous, potassium, calcium, magnesium, and sulfur. Of these macronutrients, N, P, and K are considered "primary nutrients" and are what we will focus on here. 

Why do plants need fertilizer?

As soil-base plants grow, they are constantly extracting nutrients from the soil via their roots. When growing in their natural habitat (meaning not in a pot inside our homes), they receive these essential nutrients from decomposing organic material, humus and animal excrement. When you fertilize, you are amending the soil and replenishing any nutrients that have been depleted as the plant uses them. 

It is important to note that a plant is needs these nutrients most during it's growing period. For most plants, this is spring and summer, although there are some plants that appreciate the extra boost in the winter, such as the Christmas cactus and orchids. 

NPK who?

The most common question I get regarding fertilizer is what is this NPK jargon and how does it work? You'll notice on every bottle of fertilizer it will have some numbers that look similar to this this: 6-8-6. The first number will always be nitrogen (N), second phosphorous (P), the last potassium (K). These three number make the ratio of available nutrients in that specific container. So, if I had a 1 pound container of fertilizer, 0.06 is N, 0.08 is P and 0.06 is K. The rest of the 0.80 pounds is filler product (such as sawdust and limestone) or other ingredients that provide nutrients (such as amino acids and essential oils). 

Nitty gritty.

Nitrogen is a major component of chlorophyll and the MVP in photosynthesis. It also produces proteins that produce new tissues and is particularly important for leafy plants like Ficus and Philodendrons. Using a fertilizer with a higher first number means that it contains more nitrogen and is great for helping out new growth and greening up those older leaves. 

Phosphorous is for roots, buds, fruit and flowers. It transfers energy from the roots to the buds. For plants that flower, or are grown for both foliage and flower, use a fertilizer with a higher middle number. 

Potassium is caffeine of the plant world - it's not part of the chemical makeup of a plant, but it is essential for vitality and vigor. It also produces proteins responsible for cell growth and regulates the opening and closing of the plant pores, called stomata, which is how the plant breathes (exchanging CO2 and 02) and receives water vapor. Not enough P = excessive water loss = dry plants = sad plant.

For bromeliads and tillandsias: I half the recommended amount to a spray bottle and apply to the foilage once a month during growing period.

For bromeliads and tillandsias: I half the recommended amount to a spray bottle and apply to the foilage once a month during growing period.

How to fertilize.

Okay, so now you understand the elemental nutrients required for healthy plant growth, how they work and how to understand the NPK ratio. Now it's time to do the damn thing! 

I recommend only fertilizing during a plants growing period, as this is when a plant needs these nutrients most. During dormancy a plant is not photosynthesizing nearly as much and any excess nutrients in the soil will go unused. 

Some people have a strict feeding schedule and specific fertilizer for each plant, and I say heck ya! If you want to get all nerdy like that, I'm proud. But to make things easier on myself I fertilize everything once every two weeks. I use an organic (who wants chemical crap in their house full of kitties and babies or on their food?) liquid, water soluble fertilizer that I can just add to my watering can and incorporate into my watering schedule. I follow the measurement instructions on the back of the container, but because I am using an organic product (made form fish emulsion, humic acid, and kelp extract) I can afford to be a little lazy in the measurement department (I typically go with the 'one glug, two glug" method). If you are using a synthetic fertilizer, it is very important that you follow the instruction carefully, even dilute more, as too much will burn the sensitive roots. 

If, in your plant tribe you have some guys such as orchids, african violets, or other flowering plants then feed them with a fertilizer with a higher middle number. For almost everything else (in my home anyways) I stick with a relatively balanced (meaning all three numbers are the same) fertilizer. 

Some say cacti and succulents don't need to be fertilized. In my world, I'll give them a sip as I'm passing by, why not? If I can get my  Opuntias  flower, I'd be happy!

Some say cacti and succulents don't need to be fertilized. In my world, I'll give them a sip as I'm passing by, why not? If I can get my Opuntias flower, I'd be happy!

If you find yourself in the garden center staring at the giant wall of fertilizer products, going cross-eyed, here are some of the products I use.

*Food producing plants need LOTS of food themselves to produce enough energy to fruit. I also fertilize my veggies once every 2 weeks during growing period. 

Hope this bring some new insight into this very large and nerdy topic! If you have any questions please ask below, I will be happy to help! 

 

Horticulture Center of the Pacific
Confessions Of A Plant Murderer
Orgunique BioFert