When Do I Fertilize House Plants?

When I started collecting plants, I thought I had to fertilize my plants a lot. Little did I know, that’s not the case at all! So here, I’m writing a short post on when, why, and how to fertilize your house plants.

Why do I need to fertilize house plants?

Plants need a few things in order to grow healthily. Good lighting, moisture, and nutrients. In the wild, there are tons of different elements and essential nutrients that help with plant growth. I’m not familiar with the details of all these nutrients, but some of the most important and abundant ones includes nitrogen, phosphorus, and potassium. These three elements are usually what the three numbers on fertilizer packaging represents. Also, because there are a lot more living creatures in the soil out in the wild that helps with decomposing, there’s always a consistent source of nutrients for plants in the wild. For plants in containers, there’s nothing that helps add nutrients (unless you’re able to miraculously keep earth worms alive in your pots…).

In the end, every plant needs a different amount of each element and it also depends on what the goal of each plant is. Plants that are grown for flowering or fruiting require more of specific types of element than others.

The bottom line is, fertilizing assists with plant growth, but too much of it will do more harm than good.

So when does my house plant need fertilizing?

Short Answer: When they’re growing.

You’ll notice that your house plants don’t grow vigorously all year round. In the winter, they slow down or go into dormancy. I usually start fertilizing when spring comes and for some plants, I even wait until it’s summer, after they’ve put out some new growths.

What should I use to fertilize?

I’ve used a few different fertilizer brands, and I prefer the liquid ones because they dissolve well in water. You can easily find these at plant stores, garden centres, or big box stores.

I’m currently using Marphyl Soil Enhancer on my house plants and garden plants. You can find their products on their website or on Amazon. Compared to last summer when I didn’t bother fertilizing, my plants were clearly much happier this year!

How do I apply fertilizer?

There are two ways for plants to absorb nutrients: through the soil and through the air.

Plants in Soil

For me, every time I water my plants, I pour a bit of Marphyl into my watering can and fill the rest with water. I usually tell people to follow the label (1:20 parts water to Marphyl) but I’m too lazy to measure so I just eyeball it. My estimate is that I probably end up going about 1:40. But, I also use the fertilize more often than it instructs.

Never pour the fertilizer directly into the soil!

Plants in Water Propagation

I always drop a few drops into my water propagation. For these, I use Schultz All-Purpose Liquid Plant Food because it comes with a little dropper. For a cup or water, I put 4-5 drops and I re-apply every time I change the water.

Foliar Feeding

I have a lot of house plants that are climbers (epiphytes in the wild). Instead of relying on nutrients in the soil, they absorb it through their leaves. These plants include Hoya, Dischidia, and Tillansia. For them, I use a plant spray from AgricultureRx. I do this once a month, or whenever I remember to spray them all over. Don’t over do it though! A spray or two from each direction on the plant is enough.

So that’s it! Remember to feed your plant, but keep in mind that plant growth depends SO MUCH MORE on lighting than nutrients 🙂 Feeding a plant that lives in a low light area will almost do nothing to it.