9 Best Palm Tree And Fern Fertilizers + When To Fertilize Palms

Palm trees and ferns add a touch of tropical elegance to your garden. They can also offer some much-needed shade on those hot, sunny days. No matter the type you’re drawn to, they make beautiful choices when designing outdoor spaces.

Over time, palms and ferns will deplete the naturally occurring goodness in their soil and will start to need a little extra nourishment. This can lead to questions being asked such as: What kind of palm tree fertilizer should I use? and What is the right balance of NPK balance for fern fertilizers?

No worries, I’ve got you covered with all the answers to those questions plus a complete rundown of the best palm tree and fern fertilizers currently available on the market. I’ll also be sharing my tips and know-how on how and when to fertilize palms.

Food For Fertilizing Palm Trees

Lucky for us palm tree lovers, there are lots of palm tree and fern fertilizers available on the market, each containing a blend of macro and micronutrients to help us gardeners navigate all those gardening conundrums and challenges in our quest for the perfect environment for our plants.

I’ll explain below in more detail ways in which you can overcome these challenges but it is worth noting from the offset that understanding your soil is the first step toward healthy palms. As icons of temperate climates, the soil in which they thrive is often sandy. This means nutrients can filter away before the roots can absorb them. This may leave the trees malnourished, especially in areas with heavy rainfall.

When deciding which palm fertilizer to buy consider your soil type in order to decide whether a slow-release fertilizer is best or a liquid palm fertilizer that can be applied more regularly.

Its also pertinent to say here that palms benefit from healthy doses of magnesium and iron which prevent any unsightly, yellow patches forming on their fronds, thus helping to keep them lush and green. So look out for micronutrients such as magnesium and iron in the list of ingredients if you are worried about yellow or brown fronds.

PRO TIP

Always apply palm tree fertilizer to damp soil. This moisture will help retain added nutrients, giving the roots time to absorb them. Applying fertilizer to dry soil may result in unwanted run-off and very little root absorption.

N-P-K Ratio

Palms and ferns succeed with the right macronutrient combination. The three key elements are nitrogen (N) – for consistent healthy growth, phosphorus (P) – for strong roots and lush fronds, and potassium (K) – for promoting disease and pest resistance.

While both of these species of plants contribute to a lush garden oasis, palms and ferns have very unique needs. For instance, palms require little phosphorus. Lower amounts actually help the tree absorb other nutrients more efficiently. So, look for a lower, middle number (example: 3-1-3) in your NPK ratio.

In contrast, ferns are pretty light feeders and can be delicate. Indeed, too much fertilizer, in general, can lead to burnt roots. They also prefer a more balanced NPK where all three numbers are roughly equal (example: 10-5-10 or 10-10-10). Whilst ferns do need nitrogen in order to develop lush green fronds, excessive amounts can lead to burnt leaves.

So, what exactly is NPK?

Every fertilizer label displays three numbers. These represent the N-P-K ratio of that fertilizer, indicating its proportions of nitrogen, phosphorus, and potassium. For example: a 4-2-4 N-P-K contains 4% nitrogen, 2% phosphorus and 4% potassium. All plants require these elements in order to thrive, just in different proportions, or N-P-K ratios.

Types Of Palm Fertilizer

There really is a fertilizer to suit every gardener’s needs. Whether it’s something to boost an ailing plant and needs to have an immediate impact or a slow-burn that gets to work gradually over a period of time and continues to provide nutrients when others have been absorbed or washed away. No matter what your gardening style and preference, you’ll find something that works for you and will ensure your palms and ferns stay nourished throughout the season.

Palm Tree Fertilizer Spikes

I find slow-release spikes to be very practical for outdoor palms and ferns. Fewer applications are needed because they release nutrients to the roots slowly over time. Thus, they don’t overwhelm your plants with large doses at once. Pre-measured and compact for easy storage, they carry far less risk of run-off and root burn. Not to mention less work for you. Just push them into the soil, just below the surface and you’re done.

Watering them in is not necessary either, as nutrients are released by micro-organisms that naturally live in the soil. This method of application is most beneficial in areas with significant rainfall and in most cases, tree fertilizer spikes will provide your plants with increased resistance to tree disease and pests.

Granular Fertilizer

Granules are another good slow-release choice. One that also allows you more control over the feeding process. For example, potted, indoor palms and ferns will need different amounts of feed and perhaps a higher frequency of application. Granular feeds are versatile enough for both indoor and outdoor fertilizing needs.

Heavily concentrated, granules provide consistent, hand-measured nutrients for up to three months. Often there is no need for extra watering to activate the product, a normal watering schedule is fine. Plus, a granular feed is also less likely to leach away from the plant’s roots. Simply work them into the soil, just above the root zone, under the frond canopy for effective feeding.

Powdered Fertilizer

Powder fertilizers are one of the most economical on the market and can be applied either directly into the soil around your plant’s base or diluted in water as a “tea”.

Whilst effective for many plants, powdered fertilizers are not particularly recommended for use on indoor or outdoor palms and ferns for two reasons. Firstly, a powdered fertilizer can easily be washed away whilst being watered in, and secondly, the concentrated formula does carry a substantial risk of root burn if it comes into contact with your plants.

Liquid Fertilizer

Liquids can conserve water and time, especially if you choose one versatile enough to use for the rest of your garden. However, liquid fertilizers formulated for palms and ferns may not be appropriate for any flowering plants that are growing nearby.

The biggest benefit to using a quick-release liquid formula is how fast nutrients are carried to the root system through the soil. Liquid feeds also tend to keep the pH levels in your soil balanced.

I’m a real advocate of liquid feeds especially when I have an ailing plant that needs a quick boost of nutrients however, I do strongly recommend you use this type of fertilizer with caution, as accidental over-feeding is common and can lead to root damage.

Organic Palm Tree Fertilizer Vs Synthetic

Choosing an organic or synthetic (inorganic) fertilizer is a matter of preference and result expectations. A basic understanding of the difference can help you make a solid fertilizer choice.

Organics are plant or animal-based containing manures and other natural materials. Inorganics are manufactured with minerals and synthetic chemicals. Organic feeds contain lower nutrients levels but can nourish your palms and ferns for longer periods of time while also improving the soil. Inorganic fertilizers can result in larger trees and more lush foliage. However, they do carry an environmental impact.

As I say, the choice can only be yours depending upon your gardening and plant needs. One thing is for sure, there are plenty of choices when it comes to the best palm and fern fertilizers. Let’s get stuck into my best picks.


Best Fertilizers For Palm Trees Review

I have scoured far and wide to find the best Palm and Fern Tree Fertilizers available for the general consumers’ use. My main considerations for the selection I’ve chosen are based on the quality of the palm fertilizer, nutrient balance, overall performance, and ease of use.

As well as scouring far and wide, conducting my own tests and input from my gardening expert friends, I have also considered customer reviews across most major online platforms and gardening forums that show the full level of customer satisfaction with these specific fertilizers for palm trees.


1. Jobe’s Outdoor Palm Tree Spikes 10-5-10

jobes-outdoor-fern-spikes

Made for larger outdoor palms and ferns, these pre-measured 10-5-10 feed spikes from Jobe’s fully nourish tropicals with only 2 applications per year. A consistent stream of essential nutrients goes right to the roots without the risk of run-off or smell.

If you have read any of my other articles on tree fertilizers you will know I am a huge fan of this product range. It’s simple to apply, you just push them into the ground. It’s convenient with just two applications per season. They are out of sight of my kids and dog! The results are great, so what more can I say really.

The only downside is that the spikes can crack if you’re hammering them into hard compact ground or stony ground. In this case, I would go for the granular feed below and apply it as a top dressing.

Check Jobes Palm Tree Fertilizer Spikes price here

How To Use: No measuring or spreading, simply push spikes into the soil just below the surface around the drip line in spring. Then repeat in the fall. The dosage depends on the thickness of the tree trunk and is explained on a simple table on the back of the packaging.

  • 6″ Trunk 2 Spikes
  • 9″ Trunk 5 Spikes
  • 12″ Trunk 9 Spikes

Customer Reviews: Gardeners know the effectiveness of this product when their palm fronds quickly change from yellow to a bright, healthy green. Ease of use and great value has earned this option 4.5 / 5 stars.

Pros      

  • Extremely easy and convenient to use. Only 2 applications per year required
  • Slow-release spikes that breakdown into the soil gradually to avoid a run-off
  • Perfect if you have children or pets

Cons


2. Earth Pods Bamboo & Palm Plant Food Capsules 0.2-0.2-0.4

earth-pods-bamboo

Sold by Earth Worm Technologies, this brand focus on packing their fertilizers with natural plant nutrients, minerals, growth hormones, and beneficial microbes including bacteria, fungi, and amino acids. Their exact formula is a secret, but let me tell you, it works! And not just on my ferms and palms. These tiny capsules really do make a giant difference in the root growth, frond development, and vibrancy of my bamboo and magnolia too.

The contents of these handy, mess-free capsules are said to replicate the nutrients found on a forest floor. And the low nitrogen ratio means they are gentle enough to use regularly. You can either push them into the soil of potted plants or open the capsules and sprinkle the contents directly into the soil to cover larger areas.

Not only that, but you can also make a liquid ‘tea’ for distribution over larger areas or to keep as a liquid feed for as and when your plants need feeding.

Find Earth Pods Food Capsules on Amazon

How To Use: For small potted plants, push one time-release capsule into the soil, near the root base. For small outdoor plants, open a capsule and spread the contents over the soil. Work in with a trowel and water thoroughly. Repeat every 2 weeks. Bear in mind, you’ll need 2-3 capsules for medium to large-sized plants.

Customer Reviews: Gardeners said this fertilizer offered versatility. They were impressed that this product was suitable for use for over 75 different varieties of tropicals. Awarding Earth Pods a 4.6 / 5-star rating as well as our best buy for quality, versatility, and price point.

Pros      

  • Handy, mess-free capsules mean no runoff
  • No odor unlike most other organic fertilizers
  • Low levels of nitrogen and therefore less chance of plant burn

Cons

  • A larger amount of product needed for larger plants, can become expensive

3. Jobe’s Organics Palm Tree Granular Plant Food 4-2-4

Jobes-Palm-Fertilizer

This granular, slow-release option from Jobe’s contains their trademark Biozome. Anyone familiar with Jobe’s will know that Biotone is their patented secret weapon that contains healthy bacteria and fungi that nourishes and improves the condition of soil.

This palm fertilizer also contains a nicely balanced 4-2-4 NPK ratio, so you can expect a strong root system and healthy foliage. Two vitally important factors when it comes to growing spectacular ferms and palms.

Check Jobes Granular Palm Fertilizer price here

How To Use: For palms, work granules into the soil beneath the frond canopy and water well. For ferns: Mix 1 1/2 tablespoons of feed into the soil for every 4” of plant width. Repeat every 2 to 3 months.

Customer Reviews: Fern and palm growers are impressed with the increased vitality and consistent results they get when using Jobe’s Palm Tree Feed. Palms that seem to be failing perk right up after just one application. “Very good value for money.” at 4.5 / 5 stars.

Pros      

  • Visible results with just one application
  • Improves health, vitality, and growth rate of foliage
  • Low levels of nitrogen to reduce the risk of plant burn

Cons

  • May exhibit a slight organic odor but understandable due to all-natural ingredients

4. Miracle-Gro Shake ‘N Feed Palm Plant Food 8-2-12

miracle-gro-shake-and-feed-palms

Earlier on in this article, I was explaining that ferns and palms needed magnesium and iron to help keep foliage green and lush, prevent unsightly, yellow patches from forming, and stop fronds from curling. Well, if any of those symptoms are affecting your ferns and palms then you need Miracle-Gro Shake N’ Feed Palm food. That’s because it contains both magnesium and iron and will fix the problem in no time.

It has a slow-release formula so once you have fertilized your palms and ferns they won’t need another dose for at least 3 months.

Using this product couldn’t be more simple because the cap acts as a dispenser so you can be sure you’re sprinkling an even amount of granules around your precious plants. Watch the 1-minute video below to see just how easy it is to use for yourself.

Find Micracle-Gro Palm Fertilizer on Amazon

How To Use: Blend evenly into the soil within the drip line and water well to activate being careful to avoid contact with foliage and stem or trunk. Repeat every three months during the active growing season.

How to Use Miracle-Gro® Shake 'n Feed® Palm Plant Food

Customer Reviews: Horticulturalists swear by this product because it’s suitable for indoor and outdoor ferns and palms and can even be used on many other tropicals too. Results abound in every type of climate and soil, even in drought-prone, desert regions. Giving it 4.6 / 5 stars.

Pros      

  • Contains magnesium and iron for healthy growth and impressive lush, green foliage
  • Slow-release that lasts for 3 months
  • Easy-to-use bottle dispenser

Cons

  • Can work out expensive if you need to fertilize bigger areas

5. Jobe’s Fern & Palm Fertilizer Spikes 16-2-6

jobes-spikes-for-palm

These 2-inch fertilizer spikes from Jobe’s are superb for indoor potted ferns and palms. The pre-measured, spikes are mess-free and super simple to use and the fact that they are hidden below the soil level means they are out of reach for inquisitive little fingers and paws.

This fertilizer offers a slow-release option over 2 months but also does a great job of getting to work straight away and directly to where your plants need it the most – at the roots. This blend of fertilizer from Jobes with its N-P-K ratio of 16-2-6 works well for ailing plants that need a bit of care and attention and will benefit from a boost of nitrogen. These are great for keeping your plants healthy and nourished for a full two months!

Buy Jobes Fern & Palm Mini Spikes here

How To Use: Simply insert each spike into the soil around the base of your plants. Amount used will depend on the plant and pot size. Simply divide the diameter of the pot in inches by 2 to work out how many spikes you’ll need per plant. Example: 4-inch pot will require 2 spikes and a 6-inch pot will require 3 spikes.) Insert new spikes every 60 days.

Customer Reviews: Customers are delighted to see how well this works, even in regions where tropicals don’t naturally grow. The higher nitrogen really provides a boost of nutrients to revive and invigorate new growth and keep them nourished and thriving. Awarding this product 4.5 / 5 stars.

Pros      

  • Odor-free so great as an indoor plant or container plant fertilizer
  • Slow-release spikes that breakdown into the soil gradually to avoid runoff

Cons

  • Nothing when used indoors in potted plants or small trees

6. Miracle-Gro Tree & Shrub Plant Food Spikes 15-5-10

Miracle-Gro-tree-and-shrub-spikes

The broad application options of these slow-release spikes from Miracle-Gro allow you the flexibility of use for many different trees and shrubs, including tropicals such as ferns and palms. A twice-per-year feeding provides enough nourishment to support every stage of growth throughout the year.

The people at Miracle-Gro seem to have it covered when it comes to using fertilizer spikes for feeding a whole host of trees, plants, and shrubs. Their performance and application are not too far behind Jobe’s fertilizer spikes. But due to the broad range Jobe’s offer I prefer to stick with what has worked well for me over time, whether that’s on my palm trees or whether fertilizing fruit trees, I would recommend Jobe’s as a first choice. If they are out of stock then I would go Miracle-Gro Spikes.

Miracle-Gro Tree & Shrub Spikes are available online here

How To Use: One application in spring and fall is all that’s needed for lush growth and color. Drive the recommended number of spikes (per size of tree) into the soil and water well to activate.

Customer Reviews: Consumers can’t get enough of the consistent and dependable results they get year after year, with this product. Earning this a 4.6 / 5 stars.

Pros      

  • Effective results with most perennial trees and shrubs, as well as ferns and palms
  • Only 2 applications per year required
  • Slow-release spikes that breakdown into the soil gradually to avoid runoff

Cons

  • Pre-watering may be needed if ground is dry      

7. Palm Focus Liquid Palm Tree Food 2-1-3

Palm-Focus

This liquid feed option is formulated specifically for palm trees, grown in pots or in the ground. The 2-1-3 NPK combined with mineral salts and kelp extracts focus on soil fertility which translates to healthy palm trees with vigorous growth and perfectly formed fronds.

Palm Focus is available from Amazon.co.uk here

How To Use: For potted palms, mix together 5 ml of Palm Focus per 1 liter of water in alternate waterings, year-round. For garden bed palms: 5 ml per 1 liter of water from May to August.

Customer Reviews: Palm growers are amazed at what this product has done for their potted trees. A one-liter bottle goes a long way making this very good value for money. Awarding Palm Focus an impressive 4.6 / 5 stars. It’s available to purchase at Amazon.com.

Pros      

  • Only 5 ml per liter of water when feeding
  • Quick and consistent results with potted palms

Cons

  • Over-fertilizing may result in root burn, but this is easy to avoid if you follow the directions 
  • Only available in the UK 

8. Vitax Tree Fern & Palm Feed 6-2-2

Vitax tree fern-and-palm food

Another excellent, liquid feed option is this one from Vitax which expands its fertilizing benefits to ferns, bamboos, and grasses as well as palms. The specially formulated mix of micronutrients, and 6-2-2 NPK makes this a perfect choice to nourish many of your tropical feature plants, both indoors and out.

Another fantastic liquid feed that unfortunately is only available in the UK and other European regions. But you can get Vitax Tree Fern Fertilizer shipped from Amazon.co.uk here.

How To Use: Combine 1 capful (20ml) and 2 liters of water, then pour into pre-moistened soil around the base of plants. Repeat every 7-10 days during the active growing season.

Customer Reviews: Gardeners report seeing immediate new growth and vitality in their plants with this product and are very happy with its ease-of-use. Rating this a fantastic 4.6 / 5 stars.

Pros      

  • Strong new growth in a very short time
  • Can be used for both potted and garden bed ferns and palms

Cons

  • More frequent applications needed than other product options     

9. Fertilome Concentrate Fish Emulsion Fertilizer 5-1-1

fertilome-fish-emulsion-fertilizer

This liquid feed option from Fertilome uses organic fish emulsion with a 5-1-1 NPK to encourage vibrant foliage, strong plant structure, and a robust root system in soil that needs a boost in nitrogen. Its broad use includes potted houseplants and fruits, as well as palm trees and ferns. It can also be used as a vegetable fertilizer. In my experience, it comes into its own when used on plants or small trees that enjoy light-shade, so it’s perfect for tree ferns and ferns and does great with Palms too.

How To Use: Mix 2 tablespoons per gallon (3.78 liters) and apply each month during the growing season.

Customer Reviews: Customers looking for a great product for use in clay or sandy soil are delighted with how well this product works with all types of plants, awarding this 4.6 / 5 stars

Find Fenti-lome on Amazon.com

Pros      

  • A great fertilizer to use to support strong healthy foliage growth
  • Great results for house plants and small palm trees and ferns

Cons

  • A fish based product so can smell if overused

How To Fertilize Palm Trees  

Each manufacturer will have specific instructions when it comes to how to fertilize your palms and ferns. It really all depends on what form of fertilizer you have chosen for your specific needs. Here are some more specifics about fertilizing based on climate, whether your plants are potted or planted in the ground, and in relation to the type of fertilizer you are using.

When To Fertilize Palm Trees           

If you’re growing palms in a temperate climate, meaning the temperature doesn’t drop below freezing, 3 or 4 applications of a quick-release liquid or granule feed per growing season are all that’s needed. You’ll want to plan feedings in equal time increments between the end of March to the end of October for a steady stream of nourishment.

If you live in an area where temperatures drop below freezing, and growing seasons are shorter, only two applications are necessary. The first should be scheduled after all risk of frost has passed. The second, sometime in mid-summer to make sure that your palms have enough time to absorb all the essential nutrients they’ll need before the next frost, in order to get them through the winter.

Conveniently, these practices can be followed for both potted and in-ground plantings. It’s important to remember to stick to these recommended dates, though. Feeding beyond them could show negative results like root system damage and abnormal trunk and frond formation.

If you choose slow-release spikes or granules, refer to the specific brand’s instructions. This type of feed can last anywhere from three to six months, requiring a smaller frequency of application to get that lush, tropical garden look. Be aware that some may be more beneficial for in-ground plantings than potted ones due to the N-P-K balance.

How Often To Fertilize Palm Trees                               

An effective palm tree feeding schedule can be accomplished by answering two questions. Is your palm newly planted or established? And, is it potted or planted in the ground?

Naturally, new plantings will need a little extra attention to get started and potted plants will need to be fed more frequently due to soil and fertilizer escaping through drainage holes. Established, older trees may need more feed based on size but not necessarily more attention. Let’s break it down a little further.

New plantings: It seems counter-intuitive not to add fertilizer to the soil when planting a new palm, either in a pot or in the ground. But really, palm trees don’t benefit from this at all. Palm tree roots are quite sensitive to being moved and adding a strong feed to their new home would only increase that. Likely resulting in disease or the tree failing.

It’s best to wait 3-4 months before doing this, to give the roots time to adapt to the new space. You’ll know it’s ready when the tree releases a new shoot or spear. At that point, your palm will be ready to accept some added nutrients.

Established palms: Palm trees get easier as they get older. Well-established plants will only need to be fed one to three times per growing season.

Potted Palms: Potted palms may require feeding more often than garden bed plantings. They depend solely on us to provide them with nutrients after they have depleted all that’s in the potting soil. So, depending on the type of fertilizer you choose, the feeding schedule could be anywhere from every week to every few months.

Garden bed palms: Outdoor palms usually have access to ground and rainwater which is what makes slow-release feeds so effective. They can last anywhere from three to six months and nutrients are released to the roots every time it rains or whenever you water them.

Fertilizer For Palms Plants In Pots

There are roughly 2600 species of palms around the world and only a fraction grow in pots to adorn our spaces. Typically, palms in pots require more nutrients than those planted in the ground. This is because soil nutrients will eventually become depleted once absorbed by a potted palm. Choose your fertilizer wisely by considering the age of your palm and its size. Remember, mature palms need less fertilizer than young palms but the bigger the plant, the greater quantity of fertilizer you’ll need.

It’s also a good idea to consider where your palm will be located and whether you need to consider hazards such as runoff and the risk of ingestion. To be on the safe side, I would always opt for an organic fertilizer spike such as Jobes Fern and Palm Fertilizer Spikes. They don’t smell, they are slow-release so there is no chance of runoff and they are buried beneath the soil level so they aren’t visible to children or pets.

Two coveted types of potted palms are the Sago and Majesty Palms which are familiar sights in desert and coastal regions.

Sago Palm Fertilizer   

Native to Japan and India, these beautiful plants contribute structure and grandeur. Typically planted in large pots, sago palms thrive in an environment rich in nitrogen so you’ll want to ensure that your fertilizer has a higher first digit in its NPK balance (example: 16-2-6).

An organic choice will not only provide adequate nourishment but will help to balance the pH of the soil.

Majesty Palm Fertilizer        

These regal beauties aren’t as picky when it comes to nutritional needs. Majestic palms will grow nicely with a general 10-10-10 NPK, similar to a general-purpose houseplant feed.

They are subject to the effects of over-fertilizing though so be sure to follow the suggested dosage on the label. The easy thing about this type of palm is that it can be lightly fed with each watering for consistent support, from spring to fall.

Outdoor Palm Tree Feed

It’s hard to imagine that palms have been around since the time of the dinosaurs and yet we still enjoy them to this very day. Two such examples that once adorned the paleolithic landscape are the queen and windmill palms.

Queen Palm Fertilizer

This palm can grow to great heights but is happy with just three feedings per year. Once in spring, summer, and autumn. Especially with a feed that’s rich in manganese, iron, potassium, and an NPK ratio of 3-1-3.

Any deficiency can result in yellowing leaves and withered new growth. An increased amount of fertilizer will most likely be needed as well to accommodate their larger size. The good thing is they will not definitely respond to your efforts with strong trunks and lush foliage for years to come.

Windmill Palm Fertilizer 

Similar to the potted majestic, the windmill palm has no specific needs. Once planted, it should be happy with the natural elements found in the soil. However, you may want to do a soil pH test to make sure that what it needs is, in fact, present in the soil.

If not, extra feeding may be required with a basic 10-10-10 NPK. The plus to that extra effort may be an increased growth rate in this slow-growing palm.

Fern Fertilizer 

Ferns are elegant, timeless additions to any indoor space or shade garden and require very little to thrive. This means that frequent fertilizing may not be necessary unless soil testing proves otherwise. If needed, a basic 10-10-10 NPK balance is fine.

Just keep in mind that tropical ferns can be sensitive to strong feeds so careful application is important. A tell-tale sign of overfertilizing is a browning of the frond tips.

If accidental over-feeding does occur, simply hold off with the next scheduled fertilizing to allow any build-up of product to be flushed away. Ferns appreciate more water so this won’t harm them.

Palm Tree Fertilizers Final Thoughts

Whether you’re adding palms and ferns to your collection for the first time or you’re an experienced horticulturist, I hope you have found this insightful and that you are equipped with the information and product suggestions to decide which palm and fern fertilizers you need to keep your frond-y friends happy and healthy.

So, that’s a wrap…and as a final recommendation, I would suggest you go for Earth Pods Organic Fertilizer Spikes if you need a convenient way to deliver high-quality nutrients to your potted plants. Keeping them healthy both above and below the soil level and is gentle enough to use regularly right through the growing season. Or, for outdoor palm trees go for Jobe’s Organics Palm Tree Fertilizer Spikes. The slow-release option will nourish your soil as well as keeping ferns and palms looking fabulous all year.