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Fig trees are among the least demanding of all varieties of fruit trees. With hundreds of cultivars to choose from, there is a fig tree for every grower in tropical or subtropical climates. But since they do not require much maintenance, fertilizing them can be a delicate balancing act.
As a general rule, you should only fertilize fig trees when soil nutrients are depleted or growth is stunted. In those cases, slow-release fertilizer is best and you can make your own fertilizer in the form of compost right in your own backyard!
Let’s look at specific fertilizing situations, commercially-available solutions, and some simple DIY approaches to fertilizing your fig tree.
When to Fertilize Your Fig Tree
There are several factors that you need to consider before fertilizing your fig tree. In general, fig trees are not considered heavy feeders and do not require much fertilization.
You will only need to fertilize your fig tree when the following conditions arise:
- The nutrients in your soil become depleted.
- Your tree’s new growth appears stunted.
If those conditions apply to you, the age of your tree will determine how often and at which point(s) during the growing season you will need to fertilize.
Nutrient Depletion and Competition
Fig trees prefer soils that are loamy, but they can thrive in almost any type of soil, as long as the soil is well-drained and free of root-knot nematodes. An ideal soil pH level for figs is between 6.0 and 6.5 (slightly acidic).
It is always helpful to conduct a soil test before applying fertilizers or other soil amendments. Soil tests can tell you what type of soil you have, your soil’s pH level, whether any soil-borne diseases or fungi are present, and which nutrients are already available to your tree.
Fig trees need nitrogen more than any other nutrient, and typically, they can get all the nitrogen they need from the soil. If your soil’s nitrogen levels are already plentiful, do not add more. Excess nitrogen can cause poor harvests, split fruit, and fruit souring.
However, while fig trees may not be heavy feeders, the plants surrounding them might be. If your fig tree has to compete with trees, shrubs, or other plants for nutrients, it may not be getting enough nitrogen after all.
Proper spacing can prevent nutrient competition. Fig trees that are trained to grow as bushes need about 10 feet of space, and those trained to grow as trees need as much as 20 feet of space (source).
If you already have other shrubs or trees planted in close proximity to your fig tree, your soil test will show you whether they have depleted the existing nutrients.
It is a good idea to test your soil regularly to monitor its nutrient levels. Unless your soil test indicates a need for more nutrients, do not fertilize your fig tree.
Test your soil and get specific recommendations for addressing deficiencies. Click here to learn more (link to SoilKit by AgriTech).
Monitor new growth on your fig tree for signs that it needs fertilizer. One such sign is the length of new shoots: if your tree’s newest shoots are shorter than 18 inches long, you need to apply some fertilizer (source).
On the other hand, if your fig tree’s new growth exceeds 24 inches per year, your tree is getting too much nitrogen. When a fig tree is over-fertilized, particularly near the end of the growing season, its new growth will not have time to properly harden before winter. This puts the tree at a higher risk of winter injury.
If you suspect that your fig tree may be consuming too much nitrogen, refrain from adding any fertilizers to your soil. Continue testing your soil periodically to keep track of its nutrient levels.
Age of the Tree
If your soil’s nutrients become depleted, your fig tree’s new growth appears stunted, (or both), the only remaining factor to consider is the age of your tree.
Do not fertilize when you first plant your fig tree. Allow it to settle into the soil first.
If your tree is young, less than six years old, and you are trying to encourage it to produce fruit, apply fertilizer three times: once in early spring, once in mid-May, and once in mid-July.
Once your tree is mature, six years old or older, if it is otherwise healthy, it will only need fertilizer once a year, in early spring.
How to Fertilize Your Fig Tree
The most important rule of thumb for fertilizing fig trees is that fertilizers should not be applied right at the base of your tree.
Instead, using your tree’s base as the center, apply fertilizer in a circle around your tree. This will ensure that your tree’s roots all have adequate access to nutrients.
If your tree is very young, your circle should be about 18 inches in diameter. The following year, make your circle wider, about 24 inches in diameter (source).
Continue expanding the circle as the tree grows. By the time it is mature and established, your circle should be approximately as wide as the tree itself.
Unfortunately, expert opinions vary regarding how much fertilizer growers should give their fig trees. This means that if your fig tree needs a nutrient boost, your best bet is to start with a conservative amount. You can consult a local Extension agent or other expert to learn how much fertilizer would be appropriate for your situation.
What experts do agree on is that in most cases, a slow-release formula is best for fruit trees. Slow-release fertilizers are beneficial in a number of ways:
- They provide nutrients to your tree for several weeks or months after only one application.
- The gradual release of nutrients prevents your tree from consuming the nutrients too quickly, which can cause unsustainable rapid growth, poor fruit development, and other problems.
- Many slow-release fertilizers are designed to work with the microbes in your soil. This makes them more efficient than quick-release formulas, while also improving the habitat of the beneficial microorganisms in your soil.
One of the best benefits of slow-release fertilizers is that, while you can find a wide array of options to purchase, you can also make your own (source).
Natural DIY Solutions
By far, the most common and beneficial DIY fertilizer is compost. Compost is the organic material left when fruit and veggie scraps, plant debris, paper, and other compostable waste decomposes over time. (See our guide: Compost Ingredients: Lists, Ratios, & Cautions For Beginners). When compost is added to the soil, it acts as both a fertilizer and a soil conditioner.
Compost is a great choice for fig trees because, while compost does return nutrients to the soil, it does so at relatively low levels. There is a very low risk of over-fertilization when you use compost (source).
The four most widely used composting methods involve using one of the following:
- A backyard compost pile
- A compost bin
- A compost tumbler
Creating a compost pile in your backyard is a good way to produce large quantities of compost over time.
Start by finding a spot in your backyard that is relatively dry and shady. Compost does require some moisture and heat, but too much of either can turn your compost pile into a mucky mess.
Collect a roughly equal amount of “browns” (twigs, dead leaves, and small branches) and “greens” (fruit and veggie scraps and lawn clippings). Chop or tear large pieces before adding them to the pile, and add water to dry materials. As they break down, the browns will release carbon and the greens will release nitrogen.
Moisture and oxygen are two important components in the decomposition process. Your compost pile should be damp, but not soggy. The ideal moisture level is comparable to a damp sponge.
You can supply ample oxygen to your compost pile by turning it every two weeks with a spade or pitchfork. Regular turning will also help you control the odor of your pile.
Compost piles are advantageous for gardeners who want to produce high volumes of compost to use all over their gardens. However, compost piles have some drawbacks:
- Compost piles may take a year or more to produce usable compost.
- Gardeners have limited control over the odor their compost piles will produce.
- Open-air compost piles can be very attractive to animals and insects.
- When piles become large, they can be difficult to turn.
Fortunately, there are other composting options.
Compost bins come in a wide variety of sizes, which makes them great choices for gardeners who do not have space for backyard compost piles.
Large bins can hold between 70 and 170 gallons of materials. Bins of this size are used for “hot process” composting because the large quantity of decomposing materials releases a good deal of heat, often reaching temperatures of 150℉. This high heat speeds up the decomposing process and allows gardeners to harvest usable compost in as little as three months (source).
To better understand this, see Active Composting vs. Passive Composting.
These large bins naturally take up quite a bit of space, but there are much smaller options available, including patio-sized bins that require very little space. Small bins are used for “cold process” composting because they can’t maintain the same levels of heat that the large bins can. Cold process composting can take six months or longer (source).
If you choose a large bin, adjust your ratio of browns to greens so that there are twice as many browns. Both large and small bins still require some moisture, so be sure to add water to maintain the consistency of a damp sponge.
Compost tumblers are very similar to compost bins. In fact, the only real difference is that compost tumblers are designed with cranks, baffles, and other mechanisms that allow you to turn your compost without a spade or pitchfork. If you already have a compost bin, a few simple modifications can turn it into a compost tumbler.
The composting processes are the same for bins and tumblers; however, many gardeners find tumblers much easier to manage because their mechanisms make turning and mixing the compost inside much simpler.
EJWOX’s dual-chamber tumbler (link to Amazon) allows for composting at two different stages in the decomposition process. Fill up one side and as it begins to turn to compost, you can start using the other side, continuing to make use of your kitchen waste. It contains an internal aeration bar that allows for airflow and is mounted on a powder-coated steel frame.
Vermicompost is compost that uses worms as the primary decomposers. Many gardeners initially feel squeamish about using worms, but vermicomposting has several advantages:
- You can set up a worm bin using materials you may already have on hand (source).
- Bad odors are rare. In fact, many vermicomposters keep their bins indoors.
- Worms can accelerate the production of compost.
If you are interested in getting started with vermicomposting to make fertilizer for your Fig trees, be sure to read our roundup on the 11 Best Worm Bins Based On Size, Style, Location, And Usage.
Other Natural Fertilizers
When it comes to DIY fertilizers, compost is truly the only way to go if you want to add more nitrogen to your soil. However, because compost takes so long to develop, it may not meet the short-term needs of your fig tree.
While none of the following are DIY fertilizers, they are all-natural fertilizers that are good sources of nitrogen:
- Poultry manure
- Alfalfa meal
- Feather meal
- Corn gluten
- Fish emulsion (source)
Some of these options, like corn gluten and feather meal, are slow-release fertilizers. Others, like fish emulsion, are quick-release fertilizers that can give your tree an immediate boost when applied correctly.
All of these products can be purchased from lawn and garden stores, but prices and availability will vary.
Even though these fertilizers are natural and organic, it is still a good idea to take an “easy does it” approach to fertilizing your fig tree. For fig trees, there is a thin line between sufficient nitrogen and too much nitrogen, so start with the smallest amount possible and add more only if necessary.
Other Fertilizer Choices
Composting takes a long time, and organic fertilizers can be expensive. If your time and budget are limited, it may be worthwhile to consider a synthetic fertilizer.
Synthetic fertilizers contain the same chemical compounds as organic fertilizers; the only difference is that synthetic fertilizers are made in a lab while organic fertilizers are derived from animals or plants.
An 8-8-8 or 10-10-10 fertilizer is a good choice for fig trees. Like organic fertilizers, synthetic fertilizers come in a variety of slow-release and quick-release options. For fig trees, slow-release will be the best (source).
Leonard makes 10-10-10 tree fertilizer spikes available online (link to Amazon).
When in doubt about which fertilizer will be best for your fig tree, take the results of your soil test to a local expert who can help you decide what will suit your tree and soil the best.
If your soil is fairly fertile, it may be years before you need to think about fertilizing your fig tree. During that time, you can start composting and have rich organic material to mix into your tree’s soil when it’s ready for some extra nutrients.
Compost is the best DIY fertilizer, but if your fig tree is struggling with a nutrient deficiency now, you may wish to try a quicker approach. There are a plethora of organic fertilizers available on the market that can deliver the nitrogen your tree needs.