Lemon trees can be one of the most rewarding fruit trees for home gardeners to grow. Since they grow so well in containers, gardeners in almost every climate can nurture healthy lemon trees and enjoy their fruit. However, lemon trees do require some hands-on maintenance in order to produce fruit.
There are five common reasons why your lemon tree may be failing to grow fruit:
- Pollination failure
- Water stress
- Nutrient deficiency
- Plant origin
Fortunately, each of those problems has a simple solution.
Let’s look at each of these so that we can understand the underlying cause and what you can do to get your lemon tree producing.
All fruit trees have a flowering period, usually in the spring, during which they may produce very high numbers of blossoms. In order for any tree to produce fruit, the pollen from the male part of the flower must be carried to its pistil, the female part of the flower. There, the pollen will fertilize the flower’s “egg” and develop into fruit.
Trees cannot produce fruit without successful pollination, which means they first must grow viable flowers. If your tree is producing flowers but not setting fruit, the problem is very simple: the flowers aren’t being pollinated.
Lemon trees are self-fruitful, which means each tree can pollinate its own fruit; it doesn’t need a second tree for cross-pollination. When lemon trees are grown outdoors, they rely mostly on insects to carry out the pollination process.
Indoors, however, where lemon trees can’t rely on insect pollinators, they won’t set fruit without help.
What You Can Do
If your tree is indoors, very carefully brush its flowers with a soft paintbrush after they have opened. This will carry the pollen to the pistil (source).
If your tree is outdoors, avoid using broad-spectrum pesticides that may kill pollinating insects. You can attract bees and other beneficial pollinators to your yard by planting marigolds or other flowers that pollinators love.
Young, newly planted trees may not have flowered yet. In this case, be patient. As long as the tree is still otherwise healthy, it will flower in good time.
While it’s true that you can grow lemon trees indoors in just about any climate, lemons still have certain temperature and sunlight requirements.
Lemon trees can tolerate low temperatures for short periods of time, but the optimal temperature range for lemon trees is 55℉ to 85℉.
Furthermore, in order for lemon trees to flower, the daytime and nighttime temperatures should not vary more than five to ten degrees.
If your tree is outside, the temperature may not be quite right yet for your tree to flower, or there may be too great a difference between daytime and nighttime temperatures.
However, if you grow your tree indoors, temperature variation is unlikely to be a problem–but sunlight could be. Lemon trees need at least six hours a day of direct sunlight to produce any blossoms. The leaves can adapt to lower levels of sunlight, but flowers, and thus fruit, are unlikely to develop (source).
What You Can Do
If your lemon tree is in a container, keep it indoors until temperatures outside are consistently in the 50s or higher, even at night. When you move it outside, do so gradually over the course of a couple of weeks; an abrupt environment change can cause leaf, flower, and fruit drop.
Place indoor trees near a western or southern exposure where they will have the best chance of getting six hours of direct sunlight each day. If that isn’t possible for you, use a grow lamp to supplement the sunlight they receive in a northern or eastern exposure.
Trees that are outdoors permanently are at the mercy of the weather. If your temperatures have been unseasonably cool, there is nothing to do but wait for warmer days. In the meantime, make sure to nurture your tree’s overall health with regular irrigation and fertilization.
When lemon trees don’t get enough water, they won’t set fruit and may drop whatever fruitlets have already developed. This is because water stress forces the fruits or flowers to compete with leaves for the available water, and the leaves are more likely to win.
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This is especially true during the first three weeks after flowers appear. Water stress during this period will virtually guarantee a lack of fruit (source).
Some growers make the mistake of giving their lemon trees small amounts of water every day. Even though the trees are receiving water every day, they still may be experiencing drought stress. This is especially true for trees planted permanently outdoors, where small quantities of water may not even reach the deepest roots of the tree.
What You Can Do
Get into a routine of watering your lemon trees often enough that the soil stays moist but not saturated. Let the top one or two inches of soil get somewhat dry before you water again. Lemon trees are susceptible to root rot, so it’s important to allow the soil to drain properly between waterings.
How often you irrigate and how much you give your tree depends on where it’s planted. In general, however, it’s better to water deeply but less often than it is to water shallowly several times a week.
When your tree develops flowers, be diligent about watering. During the three weeks after flowers bloom, you don’t need to increase the amount of water you give your tree, but try not to let the root system dry out completely. This will allow both leaves and flowers to flourish without competing for water.
During the winter months, you can decrease your tree’s water. This will prevent overwatering during the time that the tree is less active.
To learn more about the impact of proper watering, read Why Are My Lemons Falling Off My Tree?
Lemon trees need regular fertilization in order to flourish and set fruit.
Again, it comes down to competing for resources. When there is a lack of nutrients in the soil, the leaves and flowers will compete for them. This makes it especially important to fertilize during that three-week period after flowers develop.
A balanced fertilizer will help, but lemon trees feed heavily on nitrogen. In fact, they need twice as much nitrogen as phosphorus or potassium, so even if you apply a balanced fertilizer regularly, your lemon tree may not be receiving enough nitrogen.
Depending on your soil contents, your lemon tree may also need manganese, zinc, or iron. While these are not as crucial as nitrogen, phosphorus, or potassium, they are important to the long-term health of your tree and its overall ability to thrive.
What You Can Do
First, test your soil to learn what nutrients are already there. This can prevent you from inadvertently over-fertilizing your tree.
The AgriTech SoilKit provides a simple way to get an in-depth analysis of your soil’s qualities and needs.
You have several fertilizer options. Some experts recommend a foliar spray that you can apply directly to your tree’s flowers. This could help your tree set fruit, but it’s a short-term solution only.
It may be more effective to look for a slow-release 2-1-1 fertilizer or a fertilizer mix specially designed for citrus and avocado trees. There are also fertilizers designed for “acid-loving” plants, which includes lemons and other citrus trees.
Jobe’s Organics Fruit & Citrus Fertilizer Spikes (link to Amazon) are OMRI listed for organic gardening and promotes deep, healthy root growth.
While slow-release fertilizers are ideal, you can apply a water-soluble formula at half-strength during the tree’s flowering period to prevent nutrient competition.
Origin of the Plant
Most of the lemon trees that bear fruit for home gardeners are scions grafted onto rootstocks. If you purchased your tree from a nursery, this is probably the case.
If you planted your tree from seed, however, your tree may never bear fruit.
Lemons can cross-pollinate with multiple species of citrus, which often leads to great-tasting fruit. The seeds inside the fruit, though, will only carry the characteristics of one of the parent trees, but not both. The tree that grows from the seed may not look exactly like the tree that produced the fruit.
Furthermore, lemon trees grown from seed rarely grow large or robust enough to flower.
What You Can Do
If your tree grew from a seed, enjoy it as a houseplant or ornamental. Lemon trees are still attractive even when they don’t flower or set fruit.
You can try again with a cultivar from a nursery that’s known to produce fruit. Two of the most popular in the U.S., especially for indoor growing, are “Citron” (Citrus medica) and “Meyer”.
If your lemon tree hasn’t produced any fruit yet, the best action you can take is to nurture its overall health with water, fertilization, and if necessary, climate control and manual pollination. With the right care and with the right cultivar, there is every reason to believe that your lemon tree can produce fruit.