A major part of houseplant care that’s far too easy to neglect is soil quality. But the soil is where your plant’s root system is and where those roots absorb most of the plant’s water and nutrients. The soil you use for your plants can mean all the difference between healthy plants and plants that are barely hanging on!
So what goes into healthy, fertile soil?
This can vary greatly from plant to plant, but in general, the right potting mix will have the ideal balance of drainage and moisture retention, which means it won’t dry out too quickly or stay wet for too long. The potting mix should also contain the nutrients a plant needs to grow robust roots, strong stems, healthy leaves, flowers, fruit, etc. Finally, the right conditions for nutrient uptake must be present or the plant won’t be able to use the water or nutrients in the soil.
In this article, we’ll explain the factors that contribute to a soil’s fertility, and how you can cultivate that for the health of your plants!
Why Do Plants Need Fertile Soil?
Why is soil fertility so important? Can you just buy any bag of potting mix and plant your houseplant in it? Do you need to add things to bagged potting mix to make it more fertile?
In nature, plants grow in the ground and receive a steady supply of nutrients from organic material that breaks down into the soil, as well as an abundance of healthy microbes that aid in nutrient absorption.
Fertile soil provides the conditions plants need to grow such as moisture retention and drainage, nutrients, and helpful microorganisms that help make those nutrients more available. Low-quality soil can cause your plant to starve because it might not contain the right nutrients or the conditions to allow the plant to absorb whatever nutrients are there.
How to Check the Fertility of Your Soil
There are several simple ways to check various elements of your soil’s fertility such as pH levels and nutrient density.
Testing the pH Level in Soil
pH levels are crucial for plant health. Soil with an appropriate pH level for a particular plant will provide the right conditions for the plant to absorb water and essential nutrients from the soil.
If you’re a little rusty on pH (we get it, it’s been a while since high school chemistry), here’s a quick review:
The pH scale runs from 0 to 14, with most potting soils ranging from 3 to 10. 7 is neutral; anything above 7 is alkaline and anything below 7 is acidic. Most plants will thrive in fairly neutral soil, but there are a few out there that grow better in slightly acidic or alkaline soil. (Blueberries, for example, are known for enjoying acidic soil.)
pH is important because it affects the solubility of certain nutrients in water. Plants absorb nutrients along with water, so this is crucial for nutrient uptake! Acidic soils can also kill off helpful bacteria that improve plant health and affect nutrient absorption, so it’s important to maintain the right pH levels for your plant.
pH levels are easy to test. We like to use this 3-in-1 soil meter to test soil pH levels as well as moisture content and light quality! It’s easy to use and can provide great insight to the health and fertility of your soil.
Adjusting Soil pH for Houseplants
What should you do if your soil pH is off?
While there are ways to adjust soil pH (like adding sulfur to make soil more acidic, or lime or alkaline drops to make it more alkaline), this is a lot of work for houseplants. We find it easier to simply repot the plant into a more appropriate soil.
Do Your Plants Look Healthy?
One of the most reliable determinants of whether your plant’s soil is healthy and fertile is the condition of your plant!
If your plant isn’t growing as quickly as it should or if you’re noticing discoloration on the leaves, stem, or veins, there could be an issue with the soil. There could be other causes, though, so it’s important to check your plant’s light, water, and humidity conditions as well. And make sure it’s not root-wrapped!
If everything with your plant’s care and environment seems to otherwise be in order, it’s time to start thinking about the soil.
First, consider how old the soil is. If the plant has been in the same soil for more than a year, it could be helpful to repot in order to refresh nutrients and give the roots more room to grow.
You can also use a pH meter to test the soil and confirm or rule out inappropriate pH levels. (We like this meter because it tests soil moisture, pH, and environmental light levels.)
How to Improve Soil Fertility
Repotting isn’t always necessary to improve soil fertility, and sometimes repotting isn’t the best course of action because many houseplants are sensitive to such a big change. It’s a good idea to maintain your soil between repottings and keep your fiddle happy and healthy in its soil for as long as possible. (But after a year or sometimes two, depending on the plant, you’re probably better off changing the soil and moving up a pot size anyway.)
Here are a few simple ways to improve soil fertility.
Probiotic Supplements for Plants
Beneficial microbes in the soil can improve the bioavailability of certain nutrients; however, these microbes can gradually die off, which decreases soil fertility over time.
Adding probiotics to the soil can refresh these bacterial populations and help your plant absorb essential nutrients. We love this supplement because it’s all-natural, easy to use, and super effective!
Adding Rich Organic Material
Adding nutrient-dense material to soil can also improve its nutritional content. After all, all the microbial supplements and perfect pH in the world won’t do much good if there are no nutrients to absorb!
Some houseplant owners like to occasionally add a handful of compost from their compost piles or tabletop composters to improve soil nutrient content.
We like to use organic green compost in our Premium Indoor Potting Mix for ideal nutrient balance.
High-quality fertilizer is also an excellent option for maintaining the nutritional content of your soil! Houseplants need the right nutrients to grow beautiful leaves and strong roots and stems to support them, so it’s a good idea to fertilize regularly with a liquid fertilizer that’s appropriate for your plant.
We highly recommend our Indoor Plant Food because it works beautifully for most houseplants (just not succulents) and it’s gentle enough to use with each watering. This takes all the guesswork out of fertilizing!
Benefits of Boosting Soil Fertility
There are several benefits to maintaining your soil fertility rather than simply switching out the soil.
Extend Life of Potting Soil
Let’s face it: repotting can be a pain, especially if your plants are large and especially sensitive to repotting! Keeping your soil well aerated and fertile means you’ll have to repot your plant less often, which is less work for you and less stress for your plant.
Supercharge Your Plant’s Vitality
Consistently fertile and nutrient-rich soil means your plants will be able to grow consistently. When a plant experiences a nutrient deficiency, it can take some time to recover and start growing again. With a steady supply of nutrients and the right conditions to absorb them, your houseplants can grow uninhibited!
Minimizing the Risk of Disease
Healthy, fertile soil is also less likely to succumb to pests or pathogens that could harm your plant. No plant owner likes to deal with bacterial infections or pest infestations, so healthy soil can save you a lot of work in the long run.
Final Thoughts: How to Improve Soil Fertility
Maintaining the health and fertility of your soil should be part of your care routine if you’re serious about growing thriving, beautiful plants.
Make sure you’re fertilizing regularly, and consider adding a probiotic supplement to your regimen. When you water your plants, take a few moments to inspect the appearance of the leaves, stems, and soil surface so you can detect soil problems early and solve them before they become major issues. It’s also not a bad idea to test the soil pH occasionally!
Soil care is just part of houseplant care, but it doesn’t have to be difficult or time-consuming. It will save you so much time and headache if you stay consistent!
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