I have a potted Meyer lemon tree and my parents have a 20-foot tall lemon tree in their backyard, so we’ve been looking for a quality fertilizer to use. While there’s some information out there on lemon tree fertilizers, we wanted to test and research our options in depth. Here’s what we found makes the best lemon tree fertilizer and gets the maximum amount of fruits.
The best fertilizer for a lemon tree is one with an NPK (nitrogen, phosphorus, and potassium) ratio of 2:1:1, such as 6-3-3. For best results, fertilizers should also be organic, slow-release, and come from a reputable brand. A quality fertilizer means more nutrient uptake to your lemon tree, which means more fruits.
So, while we know the basics about lemon tree fertilizer, what should be in quality fertilizer, what are the top 3 brands, and how do we apply it? Let’s break this all down.
What Should Be in Lemon Tree Fertilizer?
The ideal lemon tree fertilizer should include a high nitrogen percentage. Other nutrients important to fruit development include magnesium, copper, zinc, and boron. While these secondary nutrients are included in most fertilizer mixes, each brand has a different primary nutrient mix or (NPK) you can choose from.
To help make shopping for lemon tree fertilizer easier, stick to these key indicators:
- 2:1:1 NPK (twice the nitrogen to phosphorus and potassium)
- Organic
- Slow-release
- Quality ingredients
All of the above factors are important in lemon tree fertilizers because they will lead to the maximum amount of nutrient uptake. After all, who wants to take the time and money fertilizing a tree to simply have most of it washed away and not used?
NPK
NPK refers to the main three nutrients for plants—nitrogen, phosphorus, and potassium. Each of these three ingredients assists plants with vital functions.
Nitrogen benefits overall growth such as foliage, phosphorus assists in root and blossom development, and potassium helps with hardiness and water retention.
All fertilizers will have an NPK analysis listed on the package which tells you a lot about which plants the fertilizers are designed for.
In the case of lemon trees, the appropriate NPK is a 2:1:1 ratio or twice the nitrogen to phosphorus and potassium. For example, a 6-3-3 fertilizer contains 6% nitrogen, 3% phosphorus, and 3% potassium.
Along with NPK, the soil’s pH is just as important.
Lemon trees prefer slightly acidic soil that’s between a pH of 6.0-7.0.
pH is an often overlooked component of soil as it sounds technical, but it’s a vital part of the formula. Without the proper pH, a lemon tree will be unable to absorb nutrients and the tree will start to die.
To ensure your lemon tree’s roots can absorb the nutrients properly, consider the changes in pH when fertilizing or amending the soil.
If you’d like an easy way to monitor the pH of your soil, consider getting a pH meter. You can check out my recommended tools page to see the pH meter I recommend.
Organic, Slow-Release, and Quality Ingredients
Organic
Organic is fairly standard in quality fertilizers as they don’t contain synthetic materials such as plastics or harmful pesticides or herbicides that can damage animals and plants.
Slow-Release
Slow-release is also important as the nutrients in fertilizer are meant to last in the soil and feed the tree for several months. On the other hand, fast release can give off too many nutrients too fast. The potency can chemically burn the tree’s roots and sometimes kill the tree.
Quality Ingredients
Quality Ingredients are also fairly self-explanatory as the fresher the fertilizer, the better it’s able to break down in the soil and be used by the tree’s roots and the soil’s microbes. Think of a tree’s nutrient uptake as similar to our own—our digestive system (and microbiome) prefers fresher food since it’s more easily digested and provides a larger amount of useable nutrients.
Now that we’re familiar with what to look for in lemon tree fertilizer, let’s take a look at the top three products that have all (or most) of these qualities.
The Top 3 Lemon Tree Fertilizers
1. Down to Earth Organic Citrus Mix
Down to Earth is my first choice when it comes to lemon tree fertilizer for several reasons:
- Reputable brand
- Better NPK
- Compostable package
Started in Oregon in the late 70s, Down to Earth is the result of American gardeners demanding more organic options to offset the countless synthetic fertilizers filling the shelves. They quickly became a part of the booming organic movement in the 80s.
Down to Earth’s Citrus Mix has an NPK of 6-3-3, which is exactly what we want for most citrus trees. This NPK benefits overall growth, especially for younger citrus trees. More mature citrus trees can also use a bit more phosphorus and magnesium to aid in flower and fruit development, but can still highly benefit from this percentage. You can see more about the nutrient analysis below.
Also, the ingredients are some of the best when it comes to store-bought fertilizers. The following ingredients are a great pairing for lemon tree fertilizer and are curated to achieve the 6-3-3- NPK.
While the compostable package isn’t a huge selling point, I do appreciate the small things, especially if they’re a little more environmentally friendly.
One note—this fertilizer is pretty smelly, which for some reason attracts dogs like crazy (likely the animal products in it). Our cattle dogs go nuts over this fertilizer and sometimes dig it up and try to eat the dirt we sprinkled it on. So, make sure to keep it out of the house if possible and away from children and pets.
Even though I usually prefer to make my own citrus fertilizer, Down to Earth is my go-to for store-bought citrus tree fertilizers.
Overall, you can’t go wrong with Down to Earth’s Organic Citrus Mix. If you’d like to see the current pricing, you can check it out on Amazon here.
2. Jobe’s Citrus Spike Fertilizer
I would recommend Jobe’s Citrus Spikes to those who are new to gardening and citrus trees (and especially potted and dwarf trees). While it can be difficult to determine when and how much fertilizer to provide, Jobe’s makes it easy with a simple table of instructions.
| Pot Diameter | # of Spikes |
|---|---|
| 12 | 2 |
| 18 | 3 |
| 24 | 4 |
| 30 | 6 |
Jobe’s Citrus Spikes have an NPK of 3-5-5. While the nitrogen level here is a bit low for young and growing citrus trees, it’s perfect for mature and fruiting citrus trees. The extra phosphorus and potassium help keep the blossoms strong and increases water retention, which is incredibly important for the tree to grow juicy fruits.
While Jobe’s is great for potted or dwarf lemon trees (like my potted Meyer lemon tree), I wouldn’t recommend it for larger, more mature trees. A disadvantage of using spikes is that it’s hard to measure how much you need for bigger, planted trees since they have more soil.
The spikes concentrate nutrients in small patches in the soil instead of the full reach of the tree. This isn’t a problem for potted trees since there’s a finite amount of soil to work with, but the mass of soil with planted trees won’t benefit much from the limited reach of the nutrients.
Either way, planted or potted, I would also caution against leaving the spikes exposed or unattended. Since they can’t be scattered throughout the soil as granulated fertilizer can, children or pets can dig them up (especially with potted trees within reach).
Overall, Jobe’s is a great option for those new to fertilizing dwarf or potted lemon trees. You can check out Jobe’s citrus spikes here on Amazon.
3. Espoma’s Citrus-Tone Fertilizer
If for some reason you aren’t interested in the two fertilizers above, I do have a third recommendation.
While I haven’t tried Espoma’s Citrus-Tone yet (my potted Meyer lemon can only take so much fertilizer), I do use Espoma’s organic potting soil for my herbs, vermicompost, and potted Meyer lemon tree. After having a lot of success from their potting soil, I highly recommend their brand as they focus on providing organic, quality ingredients.
Espoma’s Citrus-Tone has an NPK of 5-2-6, which is a good balance of nutrients for lemon trees. While it has a higher percentage of potassium than is suggested for most citrus trees, it won’t harm the tree. If anything, the fruit and tree will become hardier and retain water easier. This is especially useful if you have intermittent periods of drought or have lower potassium in your soil.
You can find Espoma’s citrus tree fertilizer here on Amazon and here’s a link to their potting soil if you’re also interested.
If you’d like to learn more about how to choose a quality fertilizer for your lemon tree, check out my recommended organic fruit tree fertilizer page.
When in Doubt, Use Compost
If you can’t decide on a store-bought fertilizer or don’t want to use anything manufactured or synthetic (I don’t blame you), then consider using compost or make homemade citrus fertilizer.
Compost makes for a great fertilizer for lemon trees as it has an abundance of fresh nutrients and microbes. These not only benefit the tree but grow the health of the soil. This soil quality provides extra benefits to the tree such as protection against diseases, better water retention, and more self-sufficiency.
For example, after I applied 2 inches of my vermicompost soil to the top of my potted Meyer lemon’s soil, it started a TON of new growth immediately (and it was indoors for the winter, without sunlight!).
Since compost is generally slightly alkaline, and lemon trees prefer slightly acidic soil (between a pH of 6.0-7.0), you can mix in some coffee grounds, peat moss, or sand for some extra acidity.
How Often Should You Apply Lemon Tree Fertilizer?
Lemon tree fertilizer purchased from a store should be applied 1-2 times per year, while homemade fertilizer or compost should only be applied every 1-2 months. This is because the nutrients from the fresher ingredients are more easily access and spread through the soil.
While buying store-bought fertilizers can be convenient, it’s usually not the best way to deliver usable nutrients to your lemon tree’s soil. Just like how we absorb more nutrients from fresh food than vitamin tablets, lemon trees also benefit from fresh ingredients. This means that we can apply less fertilizer less often.
Fresher fertilizer also helps build the richness of the soil, which keeps nutrients in the ground and retains water. For example, each 1% increase in a soil’s organic matter can help hold 20,000 gallons more water per acre.
So, while you can apply store-bought fertilizer every 1-2 months, homemade fertilizer or compost can be used 1-2 times per year. Make sure to apply it after the last frost, but before the growing season for your lemon tree (typically in the early spring).
How To Fertilize Lemon Trees
Once you determine how often you need to fertilize your lemon tree, you can start applying it. But just how much fertilizer should you use and how should you do it?
To apply fertilizer to lemon trees, start by removing any mulch, if you have any. Then measure the amount of fertilizer you need and sprinkle it under the drip line of the tree (the circumference of the canopy). Cover it back with mulch or with 1-2 inches of soil and provide a deep watering to activate the nutrients.
There are two main ways to fertilize a lemon tree. The first is with a chemical fertilizer, and the second is by using homemade fertilizer or compost.
Chemical Fertilizer
- Use the suggested amount of fertilizer (according to the instructions on the package)
- Apply away from the trunk and its roots, but still under the drip line of the tree
- Lightly bury the fertilizer 1-2 inches and try not to damage the shallow roots
- Water well to dilute and spread the nutrients through the soil
- Apply 1-2 times per year, preferably in the early spring and late summer
Compost
- Apply 1-2 inches of compost on top of the soil (if you also mulch, place it under the mulch)
- Avoid letting the compost touch the trunk or the roots directly as this can introduce mold
- Apply once per growing season, or as needed
While the above instructions apply for most chemical fertilizers, you’ll likely come across different methods, depending on which one you buy.
Keep in mind that since most store-bought fertilizers are formulated and tested differently, they may suggest their own method to apply the fertilizer.
Either way, deep watering your lemon tree is a good practice to start the spread of nutrients to the roots and train them to grow deeper and become more drought-resistant.
Overall, it’s hard to go wrong (especially if you’re using compost or a homemade fertilizer).
How Can You Tell if Your Lemon Tree Needs Fertilizer?
It’s sometimes tough to know when your lemon tree is lacking nutrients and needs fertilizer, but there are certain ways your lemon tree can tell you.
- Yellow leaves
- No new growth
- Lack of fruit
- Small fruits
While these symptoms are a good indicator of a lack of nutrients, it’s not the only cause for them. For example, yellow leaves on lemon trees are often caused by over-watering. Also, a lack of fruit can simply mean that your lemon tree is still young and needs to mature.
If your lemon tree is experiencing any issues, it’s best to use the process of elimination and start with the least invasive solutions first (start by checking the amount you’re watering and work your way up to a more invasive solution such as repotting or relocating the tree).
Can You Apply Too Much Fertilizer?
It is possible to apply too much fertilizer to a tree, but it’s generally not going to do much harm. However, if you’re using a potent fertilizer, or used far too much, provide a deep watering session for planted trees or repot trees in a container with fresh soil and then water to drain the nutrients from the soil.
It can be easy to apply too much fertilizer. Sometimes, by the time you find out, it can be too late as the lemon tree starts to die. Make sure to buy a reputable brand of fertilizer and read the instructions, especially if you’re fertilizing a dwarf or potted plant.
If you decide on using synthetic fertilizer, then you should also be aware of a few issues that can develop.
First, synthetic fertilizer is formulated to have either a slow or fast release, meaning a lot of the concentrated nutrients will spread in the soil slowly or quickly. While lemon trees are heavy feeders, they can still be overloaded if they get too many nutrients in a short time. If their soil gets too saturated with nutrients (especially nitrogen), their roots can get chemically burned. With this, the tree can die fairly quickly.
However, there isn’t much concern if you’re using a reputable brand and following their instructions. Again, when in doubt—consider using compost!
Final Thoughts
Once we applied fertilizer to my parent’s lemon tree (we used Down to Earth), the tree slowly started providing more abundant fruits.
Generally, by applying fertilizers 1-2 times per year, or compost every 1-2 months, your lemon tree should be getting all of the nutrients it needs.
As always, don’t just blindly apply fertilizer. Watch your tree over the seasons and see how it reacts and changes. You’ll find that it can often give you signals for what it needs to grow and fruit properly.
