If you’ve ever looked at a shelf full of fertilizer and felt confused by the options, you aren't alone. We often hear that plants need "food," but fertilizer is actually more like a vitamin supplement. It provides the nutrients a plant needs to build strong cells, but it doesn't provide the energy (which comes from light).
Once you understand that, the "when" and "how" of fertilizing become much simpler.
The "Weakly-Weekly" Philosophy
You’ll see instructions on bottles telling you to fertilize once a month with a heavy dose, but many enthusiasts prefer the "weakly-weekly" approach. This means using a diluted amount of fertilizer every time (or every other time) you water, depending on your plants needs.
Think of it like our own diet: it’s healthier to eat consistent, balanced meals rather than trying to eat a month's worth of food in one giant sitting. This steady, low-dose approach provides a constant stream of nutrients and reduces the risk of "fertilizer burn" on your plant’s delicate roots.
Does Winter Matter?
The old-school advice is to stop fertilizing in the winter because plants go dormant. However, indoor plant care has changed.
If your home is climate-controlled and you are using grow lights, your plants may not know it's winter! They continue to grow, and if they are growing, they are using nutrients. My plants that I have under only grow lights definitely appreciate winter fertilizing. But if plants are truly "resting"—meaning they aren't pushing new growth—you can certainly scale back, but don't feel obligated to follow a strict "no fertilizer in winter" rule if your plants are still putting out new growth all winter.
Best Practices for Success
- Only Feed the Healthy: Never fertilize a sick or struggling plant. If your plant is suffering from pests, root rot, or severe dehydration, fertilizer will only add stress. Get the plant back to health first, then start feeding it again.
- Be sure to follow the instructions on the bottle: Adding too much fertilizer can burn the roots of your plant, you want to make sure that you are adding the right amount to make sure your pants have what they need without causing damage.
- Wet Soil is a Must: Never apply concentrated fertilizer to bone-dry soil. This can shock the roots and cause chemical burns. Always make sure the soil is slightly damp before you add your fertilizer solution.
- Know the N-P-K: You’ll see three numbers on every bottle (like 10-10-10). These stand for Nitrogen (foliage growth), Phosphorus (roots and flowers), and Potassium (overall health). For most foliage-focused houseplants, a balanced, all-purpose fertilizer is all you really need.
- Flush the Soil: Over time, mineral salts from fertilizer can build up in the soil, which can look like a white, crusty layer on top of the pot. Once every few months, "flush" your plants by running water through the soil for a few minutes longer than usual to wash away those excess salts.
A Note on "Growing vs. Resting"
Keep a close eye on your plants. If you see a new leaf unfurling, that plant is in "growth mode" and will appreciate the extra fuel. I always make sure I’m giving my monsteras everything they need when I see a new leaf begin to emerge. If a plant has remained stagnant for months, it’s telling you it doesn't need the extra nutrients. Let your plants’ growth rate dictate your fertilizing schedule, not the calendar on your wall.