We have a large lime tree and it made a miraculous recovery after partly falling on the neighbor’s fence (some major pruning helped). Unfortunately, while it grew plenty of fruit back, it had a hard time keeping them. So, to make sure we could continue enjoying our daily margaritas, I tried to find out why so many limes were dropping.
Lime trees commonly drop fruit as a corrective measure when the tree senses it will be overburdened or lack the nutrients to provide the fruit. This is a normal response and 90% or more of the total fruit can be lost. Limes also drop when the tree is stressed due to changes in temperature, watering, or nutrients.
If you want more information, and to get to the bottom of why your lime tree is dropping fruit, let’s take a further look into some of the most common reasons.
1. Natural Thinning
As mentioned, lime trees naturally drop a lot of their fruit to make sure they have enough nutrients to develop the 10% or so limes they have left. If the tree feels it’s weighed down too much, or can’t sustain as many fruits, it will shed them. Usually, this happens in the early summer and when the limes are about the size of marbles. This event is sometimes called “June Drop”.
So, how do you know if your lime tree is going through June Drop, or is experiencing a different, potentially serious issue?
There are three ways:
- It’s past June
- The dropped limes are larger than marbles
- The leaves are turning yellow and falling off
If any of the three are applicable, then you might have a problem with your lime tree. Don’t worry, we’re now going to explore the most common reasons why your limes might be falling off.
2. Improper Watering
Limes trees need soil that has consistent moisture. If you’re watering too little or not often enough, your lime tree could be getting stressed and dropping its fruit (and maybe even blossoms and leaves too).
The best way to water lime trees is to only water when the soil is dry. You can check this by pushing a finger 2-4 inches into the soil. When watering, soak the soil down to 2 feet deep. Since 90% of the lime tree’s roots are within this space, the tree will be sufficiently watered. Add 2 inches of compost and 4 inches of mulch to further improve water retention and nutrients.
The key to watering a lime tree successfully is to water after the top 2-4 inches of soil dries out. Usually, this means watering once every 1-2 weeks, depending on the soil and climate. In hot and dry weather, using compost and mulch will retain water and in a cooler climate, you may need to water only 1-2 times per month.
You can tell when your lime tree isn’t getting enough water when its leaves wilt and then perk up immediately after watering. Limes require deep watering, so make sure to soak the soil enough where it reaches the roots. Having well-draining soil is essential.
Mulching with coconut coir, straw, or bark can help limit the soil’s exposure to the sun and keep water in. This is usually a good practice to get into if you live in a warmer climate. The times you don’t want to mulch are when your soil doesn’t dry fast enough. In this case, skip the mulching to improve the aeration of the soil and prevent water-logging.
Potted lime trees that get too hot and dry can benefit from moving the tree to partial shade, or by putting the pot in a basket, protecting it from the sun.
On the other hand, if you’re watering too much, fruit and more leaves could fall off. In this case, pause watering and monitor the soil over several days to see how long it takes to dry out. Aim to water again when the first few inches of soil are almost completely dry.
In cooler climates, you might not need to mulch since there will be less evaporation. If you also keep your lime tree in a pot, you may want to monitor its moisture levels over time. If it stays wet for too long, water can stagnate and root rot can develop. When this happens, the roots will have a hard time respirating and absorbing nutrients from the soil, slowly killing the tree.
While root rot can be hard to fix, aerating the soil by removing the top layer (be careful to not damage the shallow roots) or repotting with fresh soil can help. If you decide to repot, know that your lime tree will likely go through transplant shock and will need proper watering and nutrients to survive the process.
If your lime tree gets watered inconsistently and goes through periods of drought, it can get drought-stressed and drop fruits to reserve water and nutrients. Keeping consistent soil moisture is key and can help maximize the amount of mature and ripe limes.
Another symptom of improper watering is leaf curl. If your lime tree has leaves that are curling, make sure to check out my recent post: How To Fix Curling Leaves on Lime Trees.
3. Temperature Swings
The ideal temperature for lime trees is 60-80ºF, although they can survive in temperatures of 35-100ºF. Swings of 30ºF or more can stress the lime into a state of survival, in which it conserves energy and thins the amount of fruit.
Along with temperature change, a change in winds can also stress the tree.
Strong winds can shift the humidity and dry out the soil and tree faster. If you have unusually strong winds, keep a close eye on your lime tree and inspect the soil’s moisture to determine if you need to increase your watering schedule.
4. Lacking Nutrients
When a lime tree lacks certain nutrients, a common response for it is to thin some of the fruit that it can’t sustain. This is why it’s important to use a proper fertilizer during the right time of year. The most common nutrient deficiencies in lime trees are nitrogen, magnesium, zinc, iron, manganese, and potassium.
The best way to fertilize a lime tree is to apply compost or a high-nitrogen mix in the early spring. A 2:1:2 or a 2:1:1 NPK formula works well for most citrus trees.
Lime trees are heavy feeders, so proper fertilization is important. Providing the macronutrients (nitrogen, phosphorus, and potassium, also called NPK), along with some of the micronutrients will be the most beneficial. Most store-bought fertilizers will provide most or all of these nutrients. However, find one that’s especially high in nitrogen to encourage growth and fruiting.
Potassium is also vital in maintaining healthy fruits and flowers. By not having enough, the flowers and fruits can begin to fall off. If you’re getting a standard citrus fertilizer, you likely don’t have to worry about a lack of potassium as it’s one of the three common macronutrients. However, if you’re mixing or making your own fertilizer, consider adding in potassium if you don’t already have some.
To maximize the nutrient uptake in lime trees, make sure the pH of the soil and water is lower than 7.0 (ideally 5.5-6.5). This is the best pH as most citrus trees prefer slightly acidic soil over alkaline ones.
For this reason, avoid using ash or biochar to fertilize your lime trees. Both materials have a very high pH, which will increase the soil to a more alkaline state.
When lime trees don’t have the right pH balance, most nutrients uptake will be blocked and the tree’s health will quickly decline. Clay soils also have naturally high alkalinity, so consider amending it with sand or compost to lower the pH.
It’s possible to over-prune your lime tree to the point where it can’t physically hold many fruits. Over-pruning can also cause the foliage to no longer generate enough nutrients to provide the fruit. Instead, the tree prioritizes restoring its foliage by sending nutrients to grow more branches and leaves, which means fewer nutrients and energy to grow fruit until it has enough of a canopy again.
As a general rule, try not to prune your lime tree unless you have dead, decaying, or diseased branches. Pruning is best at the beginning or end of the growing season (early spring or late summer). This provides enough time for the tree to heal its wounds long before colder temperatures arrive.
If you do prune in the winter or mid-summer, there’s a chance the weather will be too extreme for the tree to heal quickly. This will make the tree vulnerable to diseases and pests for a large part of the season.
When pruning, trim the canopy to let in some sunlight to cover part of the fruits (but not too much). This will help with the ripening process and boost their sweetness. Too much sun and the fruit can scald or become overripe too soon.
6. Diseases and Pests
Citrus canker is one of the most common diseases a lime tree can get. You can identify citrus canker if the tree’s leaves have patchy brown spots. It can also cause leaves to yellow. This leaf damage can block the tree from photosynthesizing and limit the number of nutrients the tree can take in and use to fruit.
Warm weather and heavy rains are the best chance for citrus canker to spread, so keep a lookout during these times. If your lime tree has citrus canker, consider using organic sprays with copper and pruning the infected leaves.
Mites and thrips are some of the pests you might run into. Both of them feed on the foliage and suck out plant cells and nutrients. This can lead to extensive damage and even stunt your lime tree if unattended. To get rid of mites and thrips, use a soapy water spray or organic insecticide if you need something stronger.
Lime trees shed fruit as a technique for survival. Dropping the fruit helps the tree by ensuring it’s not weighed down and enough nutrients are reserved if it has challenges growing or stressful weather. There are times when improper watering, pruning, nutrients, weather, and pests can be primarily affecting fruit drop and they should be corrected swiftly.
The natural loss of fruit normally happens around June, but can happen across multiple seasons if the lime tree isn’t getting what it needs.
The stages of fruiting for single-season lime trees are:
- Bud and flower formation (winter)
- Blossoming and fruit emerging (early spring)
- Fruit developing (late spring to early fall)
- Fruit ripening (late fall to winter)
Limes falling off of trees is normal during stage 3 when the fruit is developing. This is because the tree has survived the winter and successfully created many flowers and emerging fruits.
Now, its next challenge is to produce the maximum amount of mature fruits from its remaining energy and nutrients. To reach the highest number, it will have to consolidate its resources to just a few fruits.
Know that fruit drop is normal behavior, but keep a close eye on your lime tree in case it’s losing fruit in excess or at multiple times in the year.