My potted Meyer lemon was losing a few leaves recently and I thought it was about time to get fertilizer. While there’s a lot of information online about commercial fertilizer for planted trees, I wasn’t finding much on fertilizing potted citrus. So, what makes the best fertilizer for citrus trees in containers?
The best fertilizer for citrus trees in containers should have double the nitrogen compared to phosphorus and potassium (an NPK of 2:1:1) and be slightly acidic. Most brand names will contain the necessary micronutrients such as magnesium and zinc. Make sure to monitor the pH every so often as some fertilizer can make the soil too alkaline.
In this article, we’ll look at the top 3 fertilizers, along with the key ingredients, the best ways to apply fertilizer, and how often. Let’s get into it.
Top 3 Fertilizers for Potted Citrus Trees
There are many options to consider when fertilizing your potted citrus tree. First, you should decide if you want a commercial fertilizer or one that’s homemade.
Next, find out how much fertilizer you’ll need to apply depending on your pot size. Sometimes you may just need to do some trial and error to figure out the right balance. If you’re determined to get a clearer answer, you can always get your soil tested.
So, what are the best store-bought fertilizers for your potted citrus tree?
1. Down to Earth Organic Citrus Fertilizer Mix 6-3-3, 5 lb
I’ve used Down to Earth before and I like their brand. They have tons of different organic fertilizers for just about any type of plant out there (acidic and alkaline alike). Down to Earth sources their fertilizer from quality nutrients, so your potted citrus tree should be very happy with it.
Their citrus mix offers an organic fertilizer that’s made from feather meal, fish bone meal, alfalfa meal, and some minerals. This fertilizer’s NPK is spot on for citrus trees with a 6-3-3 measurement. With twice the amount of nitrogen (N), this fertilizer will provide extremely well, especially for younger citrus trees that still need to grow lots of foliage. Just make sure you provide the right amount (more on this later).
2. Jobe’s Organics Fruit & Citrus Fertilizer Spikes, 6 Spikes
Jobe’s fertilizer spikes are designed explicitly for potted trees and require no mixing or measuring. Due to the spikes being pre-measured, the only thing to check is the size of the pot. For example, my potted Meyer lemon is in a 12-inch pot, so I only use two spikes per season. Here are the other measurements found on the back of the package:
| Pot Diameter | # of Spikes |
|---|---|
| 12 | 2 |
| 18 | 3 |
| 24 | 4 |
| 30 | 6 |
The easy-to-follow instructions and the price make Jobe’s my number two pick. However, the NPK is 3-5-5, which is great for flowering and fruiting citrus trees, but I like to look for something with a bit more nitrogen when the tree is young and still needs to grow.
3. Espoma CT4 4-Pound Citrus-tone 5-2-6 Plant Food
I’m a big fan of Espoma’s organic potting soil (I use it for my potted Meyer lemon, vermicompost bin, and microgreens), but I haven’t yet tried their citrus fertilizer. However, when spring is here, I’ll be ordering this and fertilizing my Meyer lemon tree. It has great reviews and a fair price, so it seems like a pretty safe bet.
What to Look for in Potted Citrus Tree Fertilizer
When planted in a garden, citrus tree roots will grow and spread, pulling nutrients from the surrounding soil as needed. When growing a citrus tree in a pot, there’s no other soil from which it can draw nutrients. Because of this, the tree needs to be watered and fertilized well to survive.
Most fertilizer packs will provide an NPK ratio, along with information regarding pH levels and other nutrients included:
- NPK ratio – NPK refers to the ratio of nitrogen (N), phosphorus (P), and potassium (K) within the fertilizer. Citrus trees thrive on high nitrogen ratios and require a balance of at least twice the amount of nitrogen as phosphorus and potassium.
- pH – Citrus trees prefer to grow in highly acidic soil (pH of 5.5-6.5). If the soil isn’t acidic enough, citrus trees won’t be able to proper absorb nutrients. With that in mind, acid-based fertilizers are a better choice, especially when coupled with an acidic soil mixture.
- Quality – Due to the amount of watering required, finding the right kind of fertilizer is essential to prevent it from leaching away. Similarly, the fertilizer should contain high nitrogen levels and several extra nutrients needed for better growth, such as sulfur and magnesium.
- Organic – Organic fertilizers are often slow-release due to the soil having to break down the larger particles and nutrients. This slows down the rate they leach away during the frequent watering. In contrast, chemical fertilizers are very soluble, and it can be easy to overdo it.
Soil Mix
For potted citrus, the soil mix is highly important and should be carefully selected. Since citrus roots are susceptible to root rot, the soil mix should be lightweight and promote drainage and aeration. Compounds that contain wetting agents should be avoided.
For best results, soil containing large particles, such as wood chips, peat moss, or coarse sand, will help to prevent the root from becoming saturated. Using potting soil by itself is not recommended as it has small, uniform particles that can compact quickly and hold too much water.
I recently put together a guide on how to make your own citrus potting soil at home, so make sure to check it out.
Fertilizers
As mentioned above, citrus trees require lots of nutrients to grow, and the majority of the nutrients comes from adding fertilizer.
Some of the top nutrients to look out for when purchasing citrus tree fertilizer are:
- Macronutrients: Nitrogen, phosphorus, potassium
- Micronutrients: Zinc, copper, manganese, calcium, magnesium, boron
How to Apply Fertilizer to Your Potted Citrus Tree
There are three methods to choose from when applying fertilizer to your potted citrus tree:
- Liquid
- Dry
- Spikes
Each of these has pros and cons, and choosing the right method will depend on the plant’s size, location, and environmental factors.
Liquid Fertilizer
Liquid fertilizer is often concentrated and will need to be diluted to apply. Follow the guidelines on the container, and be sure to account for the size of the pot used to house the tree.
- Pros: Liquid fertilizer is easy to find and comes in large enough containers to last for a long time. It is also possible to use a spray bottle, which better disperses the fertilizer into the soil. Make sure to not spray the leaves or tree itself.
- Cons: The downside to liquid fertilizer is that it is far easier to leach away after being applied. If you have aerated soil, as is suggested, it’s possible that the fertilizer can be rinsed away from the roots during waterings. It can also oversaturate the soil if it’s already dense and soggy.
Dry Fertilizer
Granular fertilizer is slower releasing and should be scattered over the soil’s top – leaving a few inches free from the trunk. Gently toss the topsoil to incorporate the fertilizer. Citrus trees often have shallow roots, so avoid digging too deep.
- Pros: Dry fertilizer is an excellent option because it is slow-releasing and can feed your potted citrus tree for up to three months. Rather than adding to the soil’s water content, it is mixed in and will gently release nutrients over a longer period of time.
- Cons: When exposed to humid weather, granulated fertilizer can become clumped together. These can be dangerous to animals and children if found on top of the soil and eaten. My parent’s dogs love the smell of fertilizer and have dug it up from some planted citrus trees before. If you have pets, consider covering the fertilizer with some dirt and keeping it out of reach until for a couple weeks until it breaks down some.
Spike Fertilizers
Spike fertilizers are small containers holding fertilizer that are inserted into the soil for release over a specified period. Check the package for installation instructions, including how many to add to the pot.
- Pros: Spike are pre-measured, so provided you check the size of your pot and use the correct amount, there is little chance of over-fertilizing.
- Cons: If not adequately pushed into the soil, it is possible that animals or children can pull them free and try eating them.
How Often Should You Feed Citrus Trees in Pots?
Although each fertilizer package will have guidelines to follow when it comes to following a schedule, there are a few general rules you can follow:
- During active growth months – most often in the spring and summer – feed your potted citrus tree once per month.
- During dormant growth periods – during the winter months – avoid fertilizing your tree since it will be dormant and won’t need many nutrients.
- In colder climates, move your citrus indoors as new growth can be damaged by frost. However, some cold weather (above 40ºF) can be good for citrus trees and promote more flower and fruit production.
- Once your tree begins to bear fruit, reduce feedings during active and dormant months.
In general, new growth begins in the late winter and early spring, at which time you should start active feedings. Remember, since potted citrus trees have less soil to work with, they’ll need far less fertilizer and less often than planted citrus trees.
Final Thoughts
To get the most out of your potted citrus tree, fertilization essential. Without feedings, your tree will use up the limited nutrients in the soil and then lack vital nutrition. Because of this, it will likely suffer and may not bear fruit.
If you’re not a fan of fertilizers, and don’t want to make your own either, consider applying 1-2 inches of compost on top of the soil. Compost has tons of nutrients and mineral and is almost perfect for most trees. Keep in mind that compost is generally a higher pH than citrus trees prefer, so you may need to mix in some peat or sand.
Find a fertilizer with high nitrogen levels, along with potassium, phosphorus. Most times, the necessary micronutrients will be included in the mix. Frequent watering and a scheduled feeding of fertilizer will help ensure the survival of your potted citrus tree. Be sure to check the package to see if you have a slow-release fertilizer or if you need to feed once per month.
