Best Fertilizer for Ferns

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Ferns are great for adding a tropical feel to your garden, or for injecting a bit of color to your home decor. They are available in a wide variety of shapes and sizes from the smallest pot plants to great big, rainforest tree ferns. In fact, there are around 15,000 species of fern that can be found on Earth, and some were even present when dinosaurs roamed the planet!

Curly ferns

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Relatively easy to grow, they thrive in moist, well-drained, shady sites where they can add a touch of drama and architecture to an otherwise dim area that is ordinarily hard to grow anything in. However, like all plants, ferns need some extra nutrients to give them a boost and to help them grow into strong, healthy specimens. 

Fertilizing tropical plants like ferns requires a bit of research, as too much of one thing and not enough of another can lead to damaging the plant and may even kill it off altogether. If you’re growing ferns, whether in the garden or as a houseplant and are looking for the best fertilizer for them, we’ve put together a list of our favorites below.

If you’re in a hurry and would like to know which fertilizer to choose for your ferns, check out our top pick here:

In a hurry? This is our winner!

Best Fertilizer for Ferns – Comparison Table

Best Fertilizer for Ferns – Reviews

Our Top Pick
Osmocote 274850 Smart-Release Plant Food Plus Outdoor & Indoor, 8 lbs
Our rating:

As the name suggests, this plant fertilizer from Osmocote is suitable for using on ferns indoors and outdoors. It’s also very easy to use – simply sprinkle as much fertilizer as your plant needs (there is a useful measuring guide on the back to help you work this out), mix into the soil, and water. It couldn’t be easier.

Containing 11 essential nutrients found in a fern’s natural growing habitat, the slow release nature of this fertilizer allows you to feed your ferns under fairly low maintenance conditions. It only needs to be reapplied once every six months. To make things even easier, one application will give your ferns all the nutrients they need right up until it’s time to feed them again.

This plant food is made up of lots of little nutrient granules that are covered with a semi-permeable resin which, once wet, allows the nutrients to gradually seep out into the soil where they can be absorbed by your plant. These nutrients are also temperature sensitive, so more are released during warmer active growing periods, ensuring your fern has what it needs when it needs it. 

Customers that purchased this fertilizer were amazed at how it helped the health of their plants improve, and also noticed a visible increase in leaf growth and new frond development. This amazing plant fertilizer is definitely one to use if you’re serious about getting your ferns big and beautiful!

Pros
  • Really easy to apply – simply add to the soil, mix in and water well
  • Contains 11 essential nutrients that slowly release into the soil for the plant to soak up
  • Only needs to be applied once every six months
Cons
  • As the empty nutrient shells remain visible in the soil, it can be easy to forget when it’s time to reapply

Jobe's 05101 Fern & Palm Fertilizer Spikes, 30 per Blister Pack, 24 Pack
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Specially formulated for use on indoor ferns and palms, these fertilizer spikes make it easier than ever to keep your plants healthy and strong. 

Inserting the spikes down into the soil so they slowly release directly into the roots, gives your ferns a continuous supply of nutrients right where they need them most. By inserting them directly into the soil as one piece, you’re also guaranteed to be getting all of the fertilizer’s benefits without risking any spillages, wastage or evaporation. 

These clever little spikes contain a mix of nitrogen, phosphate, calcium, magnesium, and sulfur, all of which will feed your fern and encourage growth without overfeeding, and one spike will last for two months, so you won’t have to worry about remembering to feed too regularly. 

People that have purchased these fertilizer spikes noticed new fronds coming from their ferns after using them for just a few weeks and, in some cases, they have even managed to bring back ferns that seemed to be on the brink of dying.

Pros
  • Solid spikes inserted directly into the soil means no mess or wastage
  • Contains all the nutrients that your fern needs to grow healthily
  • The limited, slow-release formula removes the risk of overfeeding
Cons
  • These have been specially formulated for indoor use only, so can’t be used on ferns out in the garden

Dr. Earth Exotic Blend Palm, Tropical & Hibiscus Fertilizer 24 LBS.
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Carefully designed for exotic plants, palms, and ferns, this fertilizer uses a proven scientific formula that provides optimal levels of plant nutrition to give you the amazing results you’re hoping for.

Handcrafted from feed-grade ingredients and enriched with multi-minerals and proteins found in plants, fish, bone and mined minerals, this organic plant food helps to naturally promote the nutrient levels in your soil and, in turn, feed your plants with everything they need to grow big and strong. 

Fantastic for using on an array of other tropical plants as well as ferns, Dr. Earth’s contains no synthetic materials, chicken manure or toxic chemicals, and is a great choice for anybody who is looking to use all-natural ingredients or wants to garden organically. 

The organic properties of this fertilizer make it safe to use around pets and children, and customers that have used this feed on their plants found that it helped to increase both their size and growth rate.

Pros
  • Made from all-natural, organic ingredients
  • Promotes nutrient levels within the soil to help feed your plants
  • Can be used across a range of tropical plants
Cons
  • The smell is quite strong, so is best made and used outside only

Miracle-Gro Water Soluble All Purpose Plant Food, 10 lb
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Packed full of essential nutrients that will help your plants grow strong and healthy, this all-purpose plant food from Miracle Gro is water-soluble and gets straight to work delivering goodness to your plants, whilst guaranteeing to not burn them. 

Safe for use on houseplants and garden plants, it’s balanced formula has been designed to work instantly, providing feed to all of your plants and giving them exactly what they need. It’s also incredibly simple to use! Just add one scoop per gallon of water to a watering can, fill with water, and away you go. 

Ideal for use on container grown ferns and hanging baskets where soil nutrient levels are limited and can easily dry out in the warmer months, this instant-acting formula will feed your ferns without any risk of it evaporating away before your fern has had the chance to use it.

Regular feeding every two weeks with this fertilizer will give you the best results, and you will be able to see a noticeable difference in the general health of your ferns as well as an increase in new fronds.

Pros
  • Starts working as soon as it hits the soil, making it ideal for container-grown ferns
  • Can be used on houseplants and out in the garden
  • Guaranteed to not burn leaves
Cons
  • Has a more regular feeding schedule than other fertilizers, so can’t be mixed into the soil and forgotten about for several months

Tree Fertilizer, Tree Secret 64oz, Save Your Dying Tree, All Natural, Bioavailable, Loaded with...
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If you’re looking for a product to fertilize your tree ferns with, then this blend of over 60 natural ingredients from Dr. Jimz is just what you need! Created with optimum health in mind, this plant feed will help to strengthen your fern and reduce the risk of disease.

Tested by microbiologists at Boise State University, Tree Secret has been shown to provide a 70% increase in beneficial bacteria within the soil just 24 hours after it was applied. This organic matter in the soil provides everything your plants need to thrive into strong, colorful specimens.

Its slow-release formula ensures that not all of the nutrients are used up at the same time, meaning that your plants and tree ferns have what they need when they need it, rather than having to take up as much as they can whilst it lasts. 

The nutrients found within this fertilizer will also help your plants to heal themselves and strengthen their immune systems, making it easier for them to fight against any threat of disease.

Pros
  • Strengthens your plants and reduces the risk of disease
  • The slow-release formula ensures plants have nutrients available when they need them
  • Proven to add a 70% increase to beneficial bacteria within the soil after just 24 hours
Cons
  • Customers have found that, as this isn’t a concentrate, you require quite a lot of fertilizer for each plant

Best Fertilizer for Ferns – Buyers Guide

What to look out for when buying fertilizer for a fern

Ferns, although easy to grow, do need to have extra nutrients added to them in order to grow strong, healthy and to help them naturally combat any risk of disease. By applying fertilizer to your ferns, you can help them soak up these extra nutrients and ensure they can be as healthy as possible.

Indoors or Outdoors

The first thing to consider when buying fertilizer for your ferns is where you are actually growing them, to begin with. Some fertilizers are only suitable for indoor use, some for outdoor use, and some can be used in both situations. Make sure to check this information before finalizing your choice.

Ease of Maintenance

Another thing to give some thought to is how low-maintenance you’d like feeding your ferns to be. With today’s busy lifestyle, it’s all too easy to forget about these little jobs around the home and garden, and you may also not have the time to feed them regularly. 

If this is the case, look for a slow-release fertilizer that will let you add the nutrients to the soil, walk away, and let it get on with its job for several months at a time.

Overfeeding

Another good reason to think about choosing a slow-release fertilizer is that, although regular feeding will result in lush frond growth, it can also weaken the roots. This isn’t only potentially damaging to the plant but can cause them to become dislodged during high winds or dry conditions. 

Slow-release pellets or plant spikes will feed your ferns gradually over time, and deliver the nutrients they need when they need them. 

Nitrogen Levels

One thing to look out for when choosing a fern fertilizer is the levels of nitrogen it contains. Too much nitrogen can cause ferns to turn brown at the edges of their leaves and can also cause burning on the tips of the roots too.

To prevent this from happening, choose a fern food that has equal parts nitrogen to ammonia. This can be found by looking at the NPK levels (Nitrogen – Phosphorus – Potassium) on the fertilizer bottle, and these will read along the lines of “15-5-15”.

Time of Year

Keep the time of year in mind when fertilizing your ferns as well. Ferns that are grown outside will not need feeding over winter as this is when they become dormant.

A slow-release fertilizer should be given once spring arrives, and then given throughout the growing season. Once fall has come, you may choose to divide your ferns and replant them in different areas around your garden. If you are doing this, there is no need to add a fertilizer to the soil, and doing so could result in brown-edged leaves or burnt roots. 

Ferns that are being grown indoors won’t go dormant since they are not experiencing outside temperatures, so these can be fertilized all year round. In this case, an instant-acting fertilizer may be more beneficial as the fern has a limited amount of soil available to it to draw nutrients from, and slow-release fertilizers, particularly liquid ones, may evaporate away if the soil is allowed to become too dry.

However, if you prefer the idea of a slow-release plant fertilizer for your plants, then plant spikes are a great choice for ferns that are grown in containers indoors.

Hanging Baskets

If your ferns are growing in hanging baskets, an instant-acting fertilizer would be a good choice as it will add the nutrients to your soil and allow your ferns to drink them up without the risk of rain slowly washing away any slow-release formulas before they’ve had a chance to be absorbed. 

Mimicking Natural Habitats

A fern’s natural habitat is the bottom of forest floors, where they thrive in the shade and suck up all the nutrients added to the soil from decaying leaves. These nutrients include nitrogen, phosphorus, potassium, and calcium. When buying fertilizer for your ferns, make sure that these nutrients are within the mix so you can recreate their natural feed as much as possible.

By purchasing a good quality fertilizer that has all the nutrients and minerals your fern needs to grow strong, you should not only see an improvement in the overall health of your plant but will also see new growth, an increase in size and you’ll be helping to keep them disease-free.

Frequently Asked Questions

How often should I fertilize my ferns?

After initially planting your ferns, it’s a good rule of thumb to wait for around 4 – 6 months before adding any fertilizer to the soil. Once this time has passed, a slow-release plant fertilizer can be given to your ferns. The timescales on reapplication of slow-release fertilizers can vary depending on the brand, but generally tend to be somewhere between two and six months.

Why are the edges of my fern’s leaves turning brown?

Brown leaf edges on ferns are caused by nitrogen levels in the soil being too high. High nitrogen levels don’t only cause brown edges on leaves, but can also burn the tips of your ferns roots. If you’ve noticed brown, burnt looking edges on your fern, switch to a fertilizer that has equal parts nitrogen to ammonia. 

Why are slow-release fertilizers better for ferns

Compared to other foliage plants, ferns aren’t generally that hungry. Applying a slow-release fertilizer will gradually feed your ferns, rather than giving them a hit of nutrients all at once, and will generally keep them happier. Overfeeding ferns can cause their roots to weaken, which can result in them uprooting during high winds or dry periods.

What fertilizer is best for ferns grown indoors?

If you’re growing ferns as houseplants, you can choose between a slow-release or an instant-acting plant fertilizer. Slow-release plant spikes are a good choice to feed your ferns gradually over time and are also a low-maintenance way of feeding. An instant-acting fertilizer will encourage your fern to take the nutrients up straight away, and will reduce the risk of any evaporation other slow-release liquid fertilizers may suffer from when applied to indoor-grown ferns. 

What minerals should I be looking for in a fern fertilizer?

Ferns naturally feed on the nutrients and minerals left behind from decaying leaves on the forest floor. These minerals include nitrogen, calcium, potassium, magnesium, and phosphorus. Any plant fertilizer that contains these will help recreate your fern’s natural diet and allow it to grow healthy and strong.

Best fertilizer for ferns

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