How to fertilize houseplants
When it comes to caring for houseplants, one of the most important things to learn about is fertilizer. For instance, you’ll need to know how often to feed your houseplants, what kinds to use, and what time of year is preferable for feeding. When used properly, fertilizer can go a long way to helping your green buddies grow, bloom, and become stronger!
What is Fertilizer?
Sometimes called plant food, fertilizer is more of a supplement. Food implies energy, and that’s not what fertilizer is for. Houseplants already create their own food with photosynthesis, which involves making both oxygen and simple sugars (energy, food) out of sunlight, carbon dioxide, and water.
Indoor plant fertilizer is more like a nutritional supplement, helping houseplants perform their natural growth processes. It also makes the soil more suitable and habitable in general, as an imbalance in the soil can cause a houseplant to become sick. Plants need the proper lighting, temperature, and watering schedule before they can be fertilized – and not all fertilizers are suitable for all plants. Read below to see what kinds to use for which plants and when.
Types of Houseplant Fertilizer
Organic fertilizers are plant- and animal-based, and they include things like composted fruits and veggies, eggshells, fish emulsions, and good ol’ fashioned manure (particularly from cows, horses, goats, and sheep).
While you probably don’t want to add straight manure to indoor plants, it’s a common enough ingredient in potting soil. It can also be extremely beneficial to supplement your houseplants with composted food from your own composter.
Organic fertilizers tend to degrade and absorb more slowly than their inorganic counterparts, so it’s best to use a mix to feed your plants. This will ensure plants have the nutrients they need for optimal growth, now and later.
Inorganic fertilizers have been derived from non-organic sources (such as a mine) and are the most common that you’ll find in the store, usually in the form of a liquid or powder. Most of these are potent and slow-release, gradually introducing nutrients to the soil and giving plants time to absorb them.
Dry fertilizer is usually reserved for outdoor garden plants, and it is typically sprinkled around the roots and stalks in the form of powder. For best results, it should be applied when plants are dry, so it doesn’t stick to their leaves (which can harm them). Then, use water to wash any excess powder off.
For houseplants, a liquid feeder is probably what you’re looking for. This comes in the form of crystals, powder, or concentrate, and it is meant to be combined with water. It can be applied as often as once a week.
Nitrogen in Fertilizer
Nitrogen is essential to the creation of chlorophyll, which then enables houseplants to turn sunlight and carbon dioxide into simple sugars (i.e. food, energy). Nitrogen is also responsible for the formation of amino acids, the proteins that make living things. The proper amount of nitrogen fertilizer can help your houseplants be stronger and encourage faster growth.
Potassium in Fertilizer
Potassium is responsible for helping houseplants carry nutrients and water. It also plays a big role in starch synthesis. Like nitrogen, it makes plants stronger and ensures optimal growth. Specifically, potassium helps plants resist illness and survive dry spells and cold weather. It makes their leaves more resilient and their roots stronger.
Phosphorus in Fertilizer
Phosphorus is the third most important nutrient for indoor houseplants. It is a key component in photosynthesis, the conversion of nutrients, and general energy transfer. You can encourage roots to strengthen and grow and flowers to bloom with phosphorus!
Micronutrients in Houseplant Fertilizer
Some fertilizers will also contain micronutrients that are helpful to houseplants, such as zinc, boron, iron, chlorine, and copper.
Only Feed During Your Houseplants’ Growing Season (Usually Spring/Summer)
As a rule, you should only fertilize your houseplants during their growing season, which for most, is spring-summer. Some tropical houseplants are the opposite, like the Thanksgiving Cactus or the Bird of Paradise Flower. Instead, they have their growing season in autumn-winter.
During the dormant season, feeding can do a lot more harm than good, causing root burn and leaf browning, etc. On the other hand, if you live somewhere that doesn’t experience the classic four seasons, you can continue to apply indoor plant fertilizer all year – reducing the frequency when temperatures cool (typically in autumn and winter).
How Often to Fertilize Indoor Plants?
How often depends largely on the type. Store-bought fertilizer provides directions on the container or box. Usually, it will instruct you to fertilize once every couple of weeks to once every few months. That will also depend on the time of year (and whether it is the growing season or not).
Don’t Fertilize Immediately After Repotting a Plant
When it comes to fertilizing indoor plants, make sure to give recently repotted green friends a little break. Repotting stresses houseplants, leaving their roots with tiny tears. These small wounds will suffer from burns if fertilized too soon. Let roots fully recover before feeding your green friends!
Will Fertilizing Indoor Plants Make them Grow Faster?
Fertilizing encourages houseplants to grow faster if their health is otherwise good. A plant will not grow properly if it is overwatered or underwatered or if it is sick. Plants also need adequate sunlight in order to flourish, fruit, and flower.
If a plant’s other needs are being met, then providing some extra nutrients to the soil can indeed help stimulate faster growth. This is what nitrogen-rich fertilizer, in particular, is known for!
Avoid Using Too Much Fertilizer
Overfeeding will do houseplants more harm than good, potentially causing burns, mutations, and more. Balance is key when applying any type of fertilizer.
Signs that Houseplants Need Fertilizer
- Failure to thrive (stunted growth)
- Chlorosis (paling around leaf veins)
- Yellowing of lower, older leaves
- Shrinking, shorter roots
- Curling of younger leaves
As you can see, fertilizing houseplants can bring many benefits. Just remember that fertilization is secondary to aspects like lighting, temperature, and water!