Store-bought fertilizers are often synthetic and can do more harm than good, which is why so many gardeners are looking at making their own fertilizer at home. Growing up in Florida, I was always around citrus trees. Today, I prefer trying my hand with dwarf varieties like kaffir lime and Meyer lemon and finding the best fertilizers that work for them.
The best homemade citrus fertilizer should be acidic and have a high amount of nitrogen, phosphorus, and potassium as well as calcium, iron, zinc, and magnesium. You can get many of these nutrients from coffee grounds, banana peels, Epsom salts, grass trimmings, and more.
If you cook anything at home, however little it might be, then you likely have some great fertilizer in the form of kitchen scraps or yard waste (if you currently throw out your leaves, you should seriously reconsider).
Let’s take a look at how some of these can translate to the garden and feed your citrus trees.
What Should Be in Homemade Citrus Tree Fertilizer?
When it comes to nutrients, most citrus trees have the same basic needs. Different nutrients help the plant in different ways, so it’s important to strike a balance. It’s a good practice to know which nutrients come from different foods or ingredients, so you’re not left with an over or under-abundance of either.
As with most plants, citrus trees require NPK the most (nitrogen, phosphorus, and potassium), but other trace nutrients are needed to ensure proper growth for leaves, roots, blossoms, and fruit. Without the right nutrients, the tree can become weak and have a hard time photosynthesizing. When this happens, its health quickly declines. So, it’s best to have a rough idea of which nutrients you’re aiming for when you’re crafting your homemade citrus fertilizer.
Here’s a list of the most common necessary nutrients for citrus trees.
How to Make Citrus Tree Fertilizer at Home
Now that you know the majority of the nutrients most citrus trees need, it’s time to take a look at which ingredients provide those elements and what exactly it does to benefit your tree.
To help answer this, I spent some time researching and putting together this table as a resource, so you can quickly learn how to make your own citrus tree fertilizer at home.
Keep in mind that you don’t need to hit every nutrient listed as there’s a lot of overlap and many ingredients will contain trace amounts of other nutrients and minerals.
|Nitrogen||Grass trimmings, leaves, mulch, coffee grounds||Overall growth|
|Phosphorus||Bonemeal, gelatin, leaves||Roots and blossoms|
|Potassium||Banana peels, orange peels, sweet potatoes, mushrooms, cucumbers||Overall growth, hardiness, water retention|
|Sulfur||Leaves, onion skin, broccoli stems, asparagus stalks, beans||Enzymes and proteins|
|Calcium||Eggshells, kelp, blackstrap molasses, orange peels, bonemeal||Disease resistance, pH, healthy cells|
|Iron||Kelp, blackstrap molasses, beans, spinach, cacao powder||Chlorophyll, enzymes|
|Zinc||Seaweed, potatoes, mushrooms, broccoli stems, spinach, beans||Chlorophyll, energy, cold resistance|
|Magnesium||Epsom salts, banana peels, kelp, blackstrap molasses, eggshells||Overall plant growth, photosynthesis|
|Copper||Sweet potato skins, mushrooms, leafy greens, cacao powder||Enzymes, photosynthesis, respiration, energy|
|Manganese||Pineapple cores, banana peels, grains, beans, cacao powder, beets||Photosynthesis, respiration, pollination, roots|
|Chlorine||Seaweed, ryegrass, tomatoes, lettuce, celery||Overall growth (use in very small amounts)|
|Boron||Apple cores, carrots, apricots, celery, honey||Energy, healthy cells, pollination, seeds|
Remember, don’t stress too much about including all of these items. This list is just to serve as ideas for food scraps and yard waste you might already have at home.
If you’re still feeling overwhelmed, let’s take a look at some of the most important nutrients and some example combinations you can use for your citrus trees.
Simple Homemade Citrus Fertilizer
A lot of the ingredients in the table above contain multiple nutrients, so it’s hard to get it wrong. Most of the time, as long as you’re providing enough of the main nutrients (nitrogen, phosphorus, and potassium), your tree will receive small amounts of other nutrients and remain healthy.
When it comes to ratios of the nutrients, you’ll want to aim for a 2-1-1 or a 3-1-1 NPK fertilizer for your citrus trees. That’s 2-3 parts nitrogen for each part phosphorus and potassium.
While this ratio can be hard to measure for homemade fertilizer, you can use 65-75% grass clippings, leaves, and other high nitrogen ingredients, and 25-35% phosphorus and potassium (like bonemeal and banana peels). This should ensure that the ratio is fairly approximate and you’re not going over on any one nutrient.
If you’d like some ideas, here are some simple combinations of homemade citrus fertilizer from common yard and kitchen waste:
- Grass clippings
- Banana peels
- Coffee grounds
- Banana or orange peels
All of these combinations will make for a good homemade fertilizer for your citrus trees. The leaves, grass, and coffee grounds will provide high amounts of nitrogen (coffee also has high acidity, which citrus trees prefer), while the bonemeal, eggshells, banana, and kelp provide healthy amounts of phosphorus and potassium.
Each of these macronutrients has different benefits, but some micronutrients like magnesium and potassium can help with conditions like yellow or dropping leaves.
Other times they can help with issues like fruit dropping or other diseases.
So, next time you’re cooking and have kitchen scraps like onion skins, carrot tops, or coffee grounds, consider setting them aside to make your own compost or fertilizer for your citrus tree.
The Differences Between Synthetic and Homemade Fertilizer
Many problems can happen from using synthetic fertilizer. Often times, they’re overly processed and potent to the point that they can do more harm than good.
The most common example is when synthetic fertilizers “burn” the plant. It’s not a physical burning, but a chemical one that results from having very high levels of nitrogen too close to the plant or its roots. If this happens, and the nitrogen isn’t dispersed through water or other means, it can quickly kill the roots and eventually the entire plant.
Another problem is the speed of release. Many synthetic fertilizers have a hard time slowing down the release of its nutrients, often overloading the soil and the tree. This is why there’s such a big emphasis on store-bought fertilizer packages for “slow-release”.
Granted, there are some pros when using synthetic fertilizer, such as its storability and how easy it is to work into the soil.
But while these can be convenient, many times it’s just as effective (if not more effective) and safer to use everyday scraps as nutrients for your citrus trees.
Compared to synthetic fertilizer, homemade fertilizer usually won’t have dangerous levels of nitrogen and has a ton of organic matter that needs to be broken down before all of the nutrients can be absorbed.
This means it has a natural slow-release, and one that the plant prefers.
Because many food and yard scraps take weeks if not months to break down, you don’t run the same chance of nitrogen burns as you would with synthetic fertilizers.
How Often Do You Apply Your Homemade Fertilizer?
Most synthetic fertilizers are potent enough where you can apply them once or twice per year. But homemade fertilizer can be applied once or twice a season.
For best results, apply 1-5 pounds of homemade fertilizer (depending on the size of the citrus tree) during early spring and summer. When it comes to organic matter, it’s hard to use too much.
How Do You Apply It?
You can apply your homemade fertilizer mixture just under the soil, away from the trunk of your citrus tree. Aim for 1 inch under the soil (any deeper and you run the risk of damaging the tree’s roots). Water generously to allow some of the nutrients to disperse and reach the roots.
Because it’s not as potent as synthetic, homemade fertilizer usually won’t have damaging effects on the tree or its roots. But just to be safe, keep the fertilizer mixture a distance of 8+ inches away from the trunk, but not past the drip line of the tree (the total width of the branches and leaves).
Once you apply and bury your mixture, water immediately as this will start its process of breaking down the fertilizer and providing your citrus tree with nutrients that can easily be absorbed. Over time, more organic matter will become smaller and will continue feeding your tree.
If you’d like another tip, spreading a layer of mulch around the base of the tree will help add even more nitrogen-rich material and will break down even slower. It’ll also help water retention and keep weeds away, limiting them from competing with your citrus tree.
Can You Apply Too Much Fertilizer?
It’s hard to apply too much homemade fertilizer as there’s a lot of organic matter that’s made of carbon and fiber. Because there is a whole mix of nutrients, and they’re all evenly spaced between the layers of carbon and fiber, you should be safe applying the suggested 1-5 pounds seasonally.
If you’re growing your citrus tree in a pot, you may want to consider using 1-2 pounds per growing season as there’s less ground to cover and nutrients won’t run off as much.
However, just like synthetic fertilizer, if you’re using any sort of concentrate, it’s best to dilute or disperse it. For example, Epsom salts should be dissolved in water before applying. A good ratio is 1-2 tablespoons per gallon of water.
Most other ingredients like food scraps and bonemeal don’t need to be dispersed, but it can benefit the plant if you at least mix them with the other ingredients to help provide balance.
If you are concerned about the concentration of your fertilizer, you can always dilute it in water, and apply it, similar to compost tea.
If you’re looking for a good nitrogen supplement for your citrus trees, coffee grounds are nearly perfect. Citrus trees prefer lots of nitrogen and slightly acidic soil pH, both of which coffee provides. For best results, use dried coffee grounds, as wet grounds can often clump up and create mold.
Eggshells provide a high amount of calcium and magnesium, but should be dried to remove the bacteria from raw eggs. Once dried, you can grind up the eggshells into a powder to better disperse and provide your citrus tree with nutrient absorption faster.
If you don’t have time to concoct a mix of kitchen or yard waste, you can always apply 1-2 inches of compost on top of the soil for a good balance of nutrients. Just make sure to keep it several inches away from the trunk.
While wood ash makes for a good fertilizer for most plants, it’s not a good candidate to use for citrus trees. This is because wood ash has high alkalinity which counters the acidity that citrus trees prefer. When the pH is thrown off, the tree has a hard time absorbing the proper nutrients. The same goes for charcoal or biochar.
Blackstrap molasses might seem like an odd choice for homemade fertilizer, but it contains a lot of nutrients and the sugar helps beneficial bacteria in the soil develop. If you’re using blackstrap molasses, a good ratio is 1 teaspoon per gallon of water and apply generously.
If you don’t have bonemeal readily available, you can always use Jello (gelatin) as a replacement. Simply dissolve 1 pack in 1 cup of hot water and then add 3 cups cold water. However, there are often additives in the package, so keep this in mind and don’t use it too often.
If you’re also interested in making your own homemade citrus potting soil, I spent several hours researching the best soil combinations to use for potted citrus trees, so make sure to check it out.