Olives are antioxidant-rich fruits that do well in a variety of recipes. You may have tried to grow some of your own olive trees, only to be disappointed at the time of harvest. Why did your olive trees fail to bear fruit?
Your olive tree may not be bearing fruit because:
- Your trees are too young to bear olives.
- You have a non-fruiting variety.
- Your trees are biennial-bearing.
- There’s a lack of pollination.
- High temperatures in winter can inhibit fruit-bearing.
- Water stress affects olive yield.
- Your soil is nutrient-deficient.
- A lack of sunlight inhibits flowering and fruiting.
- Pest infestations and diseases reduce fruit growth.
In this article, I’ll give you a detailed breakdown of the most common reasons olive trees fail to bear fruit. I’ll also share with you the proper ways to address any problems and get your olive tree to bear again, so stick around.
1. Your Trees Are Too Young to Bear Olives
Olive trees need time to grow and reach maturity before they first bear fruit. Most sub-varieties of olive trees will need to be at least three years old before they have a shot at producing fruit.
Keep in mind that three years is a minimum. Practically speaking, if you’re growing olive trees from scratch, you can expect to wait anywhere from five to eight years before you see a harvest.
Growing your own olives is a long-term endeavor but one that pays off in the end. Once your olive trees begin to flower, you’ll be showered with a yearly supply of fresh, delicious, homegrown olives.
If you’re a passionate gardener, you’ll probably agree with me when I say that homegrown product tastes better than commercially available stuff. Of course, this is, in large part, because of your effort that went into growing the fruit.
Anyhow, if your olive trees aren’t old enough, all you can do is wait until next year, especially if you have young trees that appear to be in healthy shape. In many instances, diminished fruit-bearing is caused by poor health and incorrect growing conditions.
As long as your young olive tree is well taken care of and shows no signs of disease or distress, there’s probably nothing to be concerned about at this point.
However, if your olive trees are of age but still refuse to produce fruit, you might find an answer from the other issues below.
2. You Have a Non-Fruiting Variety
This is unlikely to happen if you did your research before selecting your olive tree. However, if you received it as a present or got it from a newly purchased lot, it can be challenging to identify what variety you’ve got.
Olive trees have a handful of varieties that don’t produce fruit. Some cultivars might bear some fruits, but the quantity is so low and production so infrequent that it may as well not matter at all.
Here are two of the more popular fruitless olive trees:
- Majestic Beauty, also known as the Olea europaea “Montra”
- Swan Hill, also known as the Olea europaea “Swan Hill”
These fruitless olive trees are usually planted by property owners for aesthetic purposes. As you may have noticed, olive trees – native to the Mediterranean – have a unique appearance that makes them stand out from other native trees.
They’re also evergreen, so they don’t lose their leaves every fall.
Fun Fact: In some parts of the world, growing fruit-bearing olive trees is actually illegal. On the other hand, it’s acceptable to plant fruitless olive trees in restricted zones.
So, just make sure you don’t have a fruitless variety. If you do, the tree, unfortunately, won’t bear fruit, but you can still use it in a decorative capacity.
If your adult olive trees have produced fruits in the past but failed to do so this year, you can rule out the possibility of them being non-fruiting varieties with a high degree of confidence.
3. Your Trees Are Biennial-Bearing
This behavior is commonly exhibited by olive trees. Alternate-bearing trees produce a substantial harvest one year but little to none the next. Their fruit production constantly cycles through high and low, year after year. Alternate bearing is also known as biennial bearing.
How do you identify whether or not your olive trees are alternate-bearing?
- If your olive trees bore a generous amount of fruit last year but fell far short of the standard this year, the alternate bearing may be the culprit.
- If you’ve had your olive trees around for a while now, you can probably judge whether or not your olive trees are alternate bearing based on what the produce looked like in the previous years.
- If it’s only your second year of harvest, you can’t conclusively say that the lack in fruit production is due to alternate bearing, but it’s a likely scenario.
In the world of agriculture, and for those people who sell olives commercially, the alternate bearing behavior is a problem. Inconsistent produce leads to unreliable cash flow, which can cause businesses to crumble.
If you’d like your olive trees to bear fruit more consistently, here are a few steps you can take:
Fertilize Well in “Off” Years
For starters, you’ll want to fertilize your olive trees especially well during their ‘off’ year. Many farmers estimate that the low year is caused by a nutritional deficiency that results from the previous year’s generous produce.
Check Your Environment
You should also ensure environmental conditions are within acceptable boundaries. Adequate sunlight and proper watering are some of the most important factors influencing fruit quality and quantity.
Prune After Harvesting
Prune your olive trees after harvesting the fruits of the ‘active’ year. Try to leave the flower-bearing foliage intact to the best of your ability. This will help your olive tree direct more resources to fruit-bearing than foliage growth and upkeep.
4. There’s a Lack of Pollination
Pollination is how plants and trees reproduce (and, hence, bear fruit). This is usually something that takes care of itself without human intervention.
However, in certain scenarios, pollination may not successfully take place. If your olive trees fail to pollinate during the year, they won’t bear fruit.
For pollination to occur, pollen grain from the male reproductive organs of a flower must be transported to the female reproductive organs. Pollen is usually carried to the female organs by dedicated pollinators (insects and birds) or, quite simply, the wind.
The first thing we need to consider is that most olive tree varieties are not self-pollinated – they’re cross-pollinated. This simply means a lone tree can’t pollinate itself and bear fruit. You’ll need at least two olive trees near each other for them to have a shot at pollination.
If you have a single olive tree on your property and it’s not among the few that can self-pollinate, it won’t bear fruit.
Secondly, olive trees are wind-pollinated. They don’t rely on insects entirely for pollen transport, as the wind naturally does that for them.
As mentioned earlier, fruit-bearing olive trees are banned in many localities. The reason for this is that olive trees produce a lot of pollen. This free-flying pollen irritates the respiratory system and causes allergies in humans and animals.
Anyhow, while wind pollination has benefits (i.e., your olive trees won’t attract as many pesky insects), it’s also not as reliable.
Wind pollination can be impeded by:
- Hot, dry winds
- Low wind speeds
- Trees that are too far from each other
- Heavy rainfall
There’s no real practical way for you to improve the success rate of pollination. Wind pollination is most effective in densely crowded vegetation for obvious reasons.
5. High Temperatures in Winter Can Inhibit Fruit-Bearing
The olive tree originates from the Mediterranean. It’s native to a warm climate, which is why it’s a bit surprising that olive trees need a period of cold to produce fruit.
Now, olive trees prefer moderate-warm temperatures. Health-wise, they don’t do too well when faced with freezing cold. In fact, their dense external foliage is prone to frost damage, just like most other trees.
However, olive trees need some ‘winter chilling’ to kickstart flower production. That may seem a bit contradictory, but such is nature.
In essence, olive trees thrive in areas that don’t get too cold (think below freezing) but get cold enough that the tree can start making flowers. Because of this criteria, olive trees are best grown in US hardiness zones 8 through 12.
They’ll still flower in lower hardiness zones. It’s just that the freezing temperatures might leave their foliage with some frost damage.
Sometimes, in the higher hardiness zones (12 and 13), temperatures may not fall low enough during winter to kickstart flower production.
Generally speaking, olive trees need to remain exposed to temperatures under 50 °F (10 °C) for at least 200 hours for successful flowering in the upcoming spring.
This is becoming more common as temperatures rise due to global warming.
6. Water Stress Affects Olive Yield
Trees have varying water requirements. Much more so than houseplants, which you can get away with watering weekly.
For trees, it may be optimal to water generously every couple of weeks or not at all. There are a lot of factors that come into play.
Here are a few of the more important ones:
- Temperature: Water evaporates from the soil faster at a higher temperature. Trees also lose water faster through transpiration. If you live in a hotter region, you’ll have to water your olive trees more often.
- Humidity: High humidity reduces water loss through evaporation. Low humidity allows water to evaporate very easily.
- Rainfall: Naturally, you don’t have to water a tree that’s already been well-watered by rainfall.
- Soil quality: Poor-quality soil does not retain moisture well, which you have to compensate for by watering more frequently. You can improve water retention by adding compost or adding a mulch layer to the soil.
- Age of the tree: Older trees have long roots. These roots can acquire water from much deeper in the ground. Simply put, older trees have access to a greater water reserve, allowing for less frequent watering.
The benefits longer roots provide are immense. Often, in regions with moderate temperatures and a decent amount of rainfall, you don’t have to water your adult trees at all.
It’s recommended to water younger trees, though. Roughly speaking, you should water newly planted trees once every week for the first few years.
You should water your adult trees monthly. Water deeply and generously to fill up the underground reserves.
Overwatering, although far less common, is still a threat. It usually doesn’t affect trees the same way it does houseplants because excess water gets drained deeper into the soil.
Still, you can overwater an olive tree by:
- Giving it too much water during the rainy season
- Watering when the soil is already saturated
- Planting your olive tree near a body of water
- Having compacted soil
Olive trees cannot tolerate standing in water. It will result in rapid health deterioration and failure to produce flowers.
Overwatering does so much damage because it deprives roots of oxygen. Roots need oxygen to survive. Without it, they suffocate and drown.
Roots are the most important and perhaps the most vulnerable part of a tree. Direct damage to the roots can very well wreak havoc on whatever those roots were keeping alive above the soil.
7. Your Soil Is Nutrient-Deficient
Another key reason why your olive trees may not bear any fruit is the lack of essential nutrients in the soil. As you know, fruit-bearing is a resource-intensive process.
Flowering and fruit production takes their toll on the tree, which is partly why some trees bear alternately – to get in an intermittent period of rest during which the tree can replenish its nutrient reserves.
Regular garden soil is fine in most cases, but sometimes, you may have to give your olive tree a little extra fuel to encourage it to flower. Store-bought organic fertilizer is perfect for this. I recommend using balanced (1:1:1) nitrogen, potassium, and phosphorus fertilizer.
On the other hand, calcium is the most important micronutrient in olive production, a lack of which can really discourage fruit production.
You can also use homemade compost or mulch. Not only are they a great source of slow-releasing nutrients, but they also help with water retention.
Soil pH can also effectively cause a nutrient deficiency in trees planted in fertile soil. Olive trees prefer slightly alkaline conditions (a pH of up to 8). Acidic soil impedes their ability to acquire nutrients.
You can use a soil testing kit to check the pH levels of your soil yourself. Or, you can send a sample to your local gardening center and have them do it for you.
pH problems are corrected by adding appropriate reactants to the soil. For example, you would add basic or alkaline matter, such as lime or calcium carbonate, to the soil that is too acidic.
8. A Lack of Sunlight Inhibits Flowering and Fruiting
The next thing to check off your checklist is sunlight. You should aim to let your olive trees bask in direct sunlight for at least six hours every day. More than eight hours is even better.
Sunlight is essential for carrying out photosynthesis, a process that lets trees convert nutrients from the soil into sugar.
If you have a densely crowded batch of trees, thin the canopy. This will help sunlight get to the shorter trees and the lower foliage.
If you grew your olive tree in a greenhouse initially, acclimate it to direct sunlight gradually. Placing it under the sun for full days with no time to adapt will cause sunburns.
9. Pest Infestations and Diseases Reduce Fruit Growth
You should examine your olive trees for signs of illness or infection. Luckily, olive trees are hardy trees known for their general resilience. This means that an infection is unlikely in the first place, and the tree can take care of itself should it have to.
Pests can infest pretty much anything, though, so be on the lookout. They’re often too small to the naked eye unless you’re up close. Check the underside of leaves since that’s where they usually hide.
Common pests like scales, aphids, and mealybugs are usually not a big deal. They suck sap from leaves and might cause a little damage to the foliage.
I don’t recommend using strong insecticides to deal with them. Remember, you’ll be eating (or selling) the olives that grow on your trees – you don’t want them to be laced with chemicals.
Getting Your Olive Trees to Bear Fruit
While the number of possible reasons seems overwhelming, going through each of them and ruling out a few can help you get to the bottom of the problem.
So, to make things more digestible, let me give you a checklist of points to consider:
- Are your olive trees of age? Most olive trees can take 5 to 8 years before bearing.
- Are your olive trees a non-bearing variety?
- Do your olive trees perhaps bare alternatingly?
- Do you only have a few olive trees? Are they far apart? Did any conditions, such as extreme rainfall, make it difficult for pollination to occur?
- Did the temperature feel warmer than usual this year? Olive trees need a period of cold to flower.
- Is the soil nutrient-deficient or overly acidic? You can use a home testing kit to find out.
- Do your olive trees get enough sunlight? If not, is it possible to trim overhead foliage to bring in more sunlight?
- Are your olive trees sick or infested by bugs?
There are plenty of reasons why olive trees may not bear fruit. For starters, trees need to be a few years old before they reach maturity and can flower. Some olive trees are non-fruiting, while others bear fruit once every two years.
Olive trees are cross-pollinated by the wind, so if you have too few too far apart, pollination might not occur. Environmental factors such as temperature, humidity, sunlight, and rainfall also influence fruit-bearing.
Dehydration and starvation (nutrient deficiency) in an olive tree will also discourage it from bearing fruit.