How, When, and Why to Fertilize Boston Ferns

Welcome to our essential guide to fertilizing Boston Fern plants at home. As houseplants, Boston ferns are prized for their bushy foliage. These dramatic plants spread themselves out with delicate fronds to create a real jungle aesthetic. The secret to getting bountiful bushy foliage from a Boston fern is to fertilize it correctly. In this post, we’ll do a deep dive into how, when, and why you should fertilize a Boston fern. We’ll also come up with some suggested fertilizer recipes to help your plant thrive.


Fertilizing Boston Ferns – The Essentials

Boston ferns grow fairly slowly, so they won’t need a huge amount of fertilizer. Use a water-soluble fertilizer once a month during the main growing season. This should have a nitrogen-phosphorous-potassium (NPK) ratio of 20-10-20. In the winter, feed these ferns sparingly with a weaker fertilizer.


The Role of Fertilizer in Plant Health and Growth

The Role of Fertilizer in Plant Health and Growth

As well as resources like water, sunlight, and carbon dioxide, all plants need nutrients to survive and thrive. These are usually obtained from the soil through the plant’s roots. 

There are three major nutrients that plants require, each with a different benefit. Nitrogen (N) is an essential building block for thick, bushy foliage. Phosphorus (P) helps a plant develop strong roots, while potassium (K) protects the plant against diseases and makes photosynthesis more effective.

A few other nutrients are also beneficial for plants. One of these is magnesium, which increases a plant’s ability to produce chlorophyll. This vital nutrient helps give the foliage a rich green color. Calcium is also another helpful mineral.

Fertilizers help provide plants with these crucial nutrients. These products are usually sold as water-soluble solutions, which are diluted in water before being poured onto the soil. Fertilizers are also available as granules which gradually break down in the soil to release their minerals. 

Premade solutions suitable for Boston Ferns can be purchased easily enough, it’s also possible to make your own. Most fertilizers are composed of ingredients like potash, manure, and other things that provide nitrogen, phosphorus, and potassium. These are represented by the NPK rating.

Signs Your Boston Fern Needs Feeding

Signs Your Boston Fern Needs Feeding

Boston ferns grow on the forest floor of tropical jungles in Africa and Central and South America. They’re grazers, slowly absorbing nutrients from rich sources like fallen leaves. 

Because they grow slowly, there won’t be many outward signs that your Boston fern needs feeding. It’s best to feed your Boston fern a sparing amount of fertilizer during the main growing season. 

When and How Often Should You Fertilize Boston Ferns

The ideal time to fertilize a Boston fern is during the main growing season. This runs from spring through until the end of summer. This is when the plant is actively trying to grow, and fertilizer can provide a helping hand.

Because they don’t grow that quickly, Boston ferns don’t need huge doses of fertilizer. A good schedule is to provide some feed every four to six weeks during the growing season. 

During fall and winter, most plants will go dormant, including Boston ferns. Fertilizing can be reduced to once every two or three months but isn’t strictly necessary. The strength of the fertilizer dose should also be reduced.

The Best Fertilizer for Boston Ferns

Every plant responds to fertilizer a bit differently, and houseplant owners should adjust to this. Boston ferns do best with water-soluble fertilizers because they can be quite sensitive to strong chemicals and salts.

These fertilizers should have an NPK rating of 20-10-20. The main focus of a Boston fern will always be the foliage, so having plenty of nitrogen will help this flare out nicely. These plants don’t need that much phosphorus because they don’t produce flowers or fruits.

There are a few premade fertilizers that are ideal for Boston ferns. A lot of standard houseplant fertilizers will do the job, such as Miracle-Gro Indoor Plant Food

Another good option is Osmocote Smart-Release Plant Food as each dose will last six months. Orchid Fertilizer by E-Z-gro also provides the right NPK ratio for Boston ferns.

You can also make your own fertilizer, often from some surprisingly common ingredients. Banana peels contain plenty of potassium, while spent coffee grounds are full of nitrogen. 

For a more technical mix, use a 2:1:2 blend of urea, bone meal, and potash diluted with several gallons of warm water.

How to Apply Fertilizer

Water-soluble fertilizers have the advantage of being easy to apply. Simply dilute the recommended dose of the mixture as per the instructions. Then use a watering can to apply this to your Boston fern’s soil.

If you’re using everyday ingredients such as banana peels, blend them into a pulp before combining them with warm water. Coffee grounds can also be mixed with water and introduced to the soil.

Key Considerations to Be Aware Of

Key Considerations to Be Aware Of

Boston ferns are pretty sensitive, so it’s easy to apply too much fertilizer which can damage the plant quite severely, so keep an eye out for:

Burnt or dropping leaves

Many fertilizers can essentially burn plants if misapplied. That is why diluting a fertilizer is crucial. If leaves develop brown tips and start falling en masse from your Boston fern, the fertilizer might be too strong. Water it down more and feed less often for a while.

Salt buildup

Over time, fertilizers can leave behind a buildup of salts in the soil. These salts appear as white patches and can cause the soil to become toxic. If this happens, flush the soil with distilled water until the salts have been washed away. Hold off on fertilizing again for as long as six months.

Wrap Up

Getting the fertilizer right for your Boston fern may seem fiddly, but the benefits can be enormous. By correctly applying fertilizer, you’ll get thicker, bushier foliage and a much more robust plant.

Use water-soluble fertilizers with an NPK ratio of 20-10-20 every four to six weeks during the growing season. You can stop fertilizing altogether or scale it back to every two or three months in the winter.


Boston Fern Plant Care Guides:

For more, see our essential Boston Fern plant care guides:


Fertilizing Boston Ferns FAQs: 

Boston Ferns benefit from feeding and fertilizing to help keep them healthy. Since Boston Ferns are relatively slow-growing, they don’t require a lot of fertilizer, but they will suffer if you leave them without nutrients during the growing season.

Fertilize your Boston Fern once per month only from April through to September each year.

Boston ferns should be fed with a balanced fertilizer comprising nitrogen, phosphorus, and potassium components in either liquid or solid form.

A common sign of too much fertilizer includes brown or yellow leaf edges or stunted growth. Another indicator that you may be applying too much fertilizer is the presence of a crust on the soil surface, which is salt buildup from fertilizer.


Author

I’ve long been fascinated with the world of flowers, plants, and floral design. I come from a family of horticulturists and growers and spent much of my childhood in amongst the fields of flowering blooms and greenhouses filled with tropical plants, cacti, and succulents from all over the world. Today, my passion has led me to further explore the world of horticulture, botany, and floristry and I'm always excited to meet and collaborate with fellow enthusiasts and professionals from across the globe. I hold a BSc degree in Plant Sciences and have trained professionally at leading floristry schools in London and Paris.

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