Just like you need vitamins, your houseplants need fertilizer. Think of fertilizer like chewy Flintstones vitamin supplements for plants.

However, you can have too much of a good thing! Just like our health can suffer if we get too much of a vitamin or nutrient, we can also throw our houseplants out of whack by overfertilizing them.

When plants get too much fertilizer, you risk creating an imbalance of salts in the soil which can cause chemical burns to the roots and reduce your plant’s ability to absorb water, leading to dehydration.

Read more about this here.

We want to prevent this, so make sure to avoid these common mistakes when fertilizing your plants!

6 mistakes plant parents tend to make when fertilizing their houseplants

Adding too much fertilizer at once

It’s easy to assume that if a little fertilizer is good, then more must be better. Right?


Make sure to carefully read the instructions on your fertilizer label and do a little research on your plant to make sure you’re adding the right amount.

Not leaching often enough

Your plants love fertilizer in the right amounts, but you want to make sure the fertilizer isn’t just sitting in the soil.

Water-soluble fertilizers can be dissolved in water before you add them to your plants, which makes it easy to regulate the nutrients your plants are getting. They can also be easily leached from the soil.

However, when the water evaporates, nutrients called salts can be left behind and build up around the roots of the plant, so it’s important to leach your plant every four to six months or so.

To leach the plant, just put the whole pot in the sink or somewhere water can run out, slowly pour in about twice the amount of water that the pot could hold, and let it all drain out the bottom. This will wash away excess salts left behind by the fertilizer.

Poor drainage

Most houseplants do best in a pot with drainage holes so water and excess fertilizer can run out the bottom instead of sitting in the pot. If your plant’s soil can’t drain properly, you risk a buildup of fertilizer.

Not balancing your watering and fertilizing schedules

Watering and draining remove excess fertilizer from the soil, so if you’re adding more fertilizer than can drain on your plant’s watering schedule, it’s time to back off a little.

Also, make sure to adjust your fertilizing routine if you move your plant to a drier climate or if you change its watering schedule (like in the winter). Leaching is also a good idea before you make the change.

Too much slow-release fertilizer

Slow release fertilizers come in granules that you mix with the soil. A lot of people like these because you can use them less often.

But that’s the thing: You have to use them less often. They stay in the soil for a long time and don’t leach out as quickly, so read the label to ensure you aren’t using too much, too often.

Mixing different kinds of fertilizers

While it is possible to successfully combine the use of slow-release and soluble fertilizers, this is an advanced move that we don’t recommend for most beginning indoor gardeners.

It’s just way too easy to overfertilize your plants when you’re using both because it’s hard to gauge how much your plants are actually getting.

Stick with one or the other for now. Your plants will thank you!

Fertilizing sounds complicated, but it doesn’t have to be! Err on the lighter side if you’re not sure, and watch your plant closely for signs of overfertilization. You’ll get better with practice!

Trust me, I understand the frustration. I was so fed up with over fertilizing, under fertilizing, and trying to remember a schedule that we created a gentle fertilizer that you can use every single time you water without overfertilizing your plant. I just mix a little into my watering can each week when I water my plants. Easy!

Our Indoor Plant Food is available here!