Lemon trees are primarily grown outdoors but, with the information below and a little extra care, you’ll be able to grow a lemon tree indoors that will be able to thrive year-round. That said, how do you grow an indoor lemon tree?
Growing an indoor lemon tree requires watering when the top two to three inches of soil has dried out. Provide 8-10 hours a day of direct light. Use citrus potting soil, keep the air temperature range between 50-80°F and humidity up to 50%. Apply fertilizer with a high nitrogen content every three to six weeks.
This in-depth plant care guide will provide care tips you won’t want to miss so you can enjoy fresh, puckery citrus right from your indoor garden!
Taking Care of an Indoor Lemon Tree
Before I dive into everything you’ll need to know when taking care of a lemon tree that’s being grown indoors, I want to briefly introduce the lemon tree.
This way you’ll have a full understanding of the plant in your possession and why it has certain growing requirements when being grown in an indoor setting.
Lemon trees grow natively in China, Northern Myanmar, Northeast India, and other parts of Asia.
Like many plant species, the lemon tree has cultivars, and each various type produces different lemons.
The Sorrento cultivar, also known as the Femminello St. Teresa, comes from Italy. The lemons harvested from this tree are used to make limoncello, as the zest contains a lot of lemon oil.
The Lisbon cultivar produces mostly seedless lemons with plenty of juice and a thin, smooth outer skin.
Lisbon lemons are one of the most common types of lemons found in the produce aisle of mainstream supermarkets!
If not Lisbon, then the Eureka cultivar is another common favorite. This lemon tree grows fruit all year long, which is a very enchanting prospect for indoor gardeners.
The lemons harvested from the Eureka tree are appropriately known as the Four Seasons.
If you’re based in the San Diego area, then you’re a lot likelier to see the Bonnie Brae cultivar, a seedless, oblong lemon with thin, smooth skin.
From my own experience growing different types of lemon trees indoors, I would suggest beginning with a dwarf cultivar such as the Dwarf Ponderosa or the Dwarf Meyer.
The Dwarf Meyer is known for being the easiest indoor lemon tree to grow. The “Dwarf Meyer” or the “Dwarf Improved Meyer” are not only easy to grow and care for, but they also respond to the size of the pot or container you grow them in.
What I mean by this is, if you have limited space to grow your indoor lemon tree then growing a Dwarf Meyer in a medium or small container will ensure that it remains a medium or small size when fully mature.
The average size of an indoor lemon tree is going to be between three and six feet, sometimes more depending on the type.
Choosing to grow a “Dwarf Meyer” or “Dwarf Improved Meyer” and restricting it to a small container will likely keep your indoor lemon tree from growing more than four feet when fully grown.
Just don’t expect to harvest fruit overnight.
The lemon tree needs pollination (usually from an insect outdoors, but these trees can also self-pollinate), and from there, it takes another six to nine months before the fruit is ready for harvest.
Indoor Lemon Tree Plant Care
You’ve just brought home your indoor lemon tree. If you purchased it from a nursery, then the three is likely at least two years old already, perhaps even three years. It’s still considered immature but could begin producing fruit.
To put your tree in the best position to do that, follow these care tips.
Watering an Indoor Lemon Tree
Allow the soil to dry out at least an inch deep and up to three inches deep before adding water to the pot.
You can always reliably confirm how dry the lemon tree’s soil is by using the fingertip test. Insert one to two fingers as deep as your knuckles into the soil.
If that much soil is dry, then fill up your watering can, it’s time to water.
You do want to thoroughly water your indoor lemon tree when the time comes. The water should exit out of the pot’s drainage holes and even fill up the tray a little.
Maintaining the indoor lemon tree’s moisture levels is a tricky balancing act, so do be forewarned of that.
Lemon trees are very sensitive to root rot, so overwatering can quickly cause the tree to succumb to that fatal fungal disease.
On the other hand, the tree’s soil shouldn’t ever get bone-dry either.
How will you know you’ve struck that perfect balance? The leaves should never be dried, wilted, or curled, nor should you see any brown or yellow leaves. These all indicate the tree is starving for water.
Don’t be surprised if you water the indoor lemon tree every single day or close to it when it’s actively growing as well as during hot periods like the summer.
If you live in a hot region, your rate of watering is going to be more so than someone who’s in a more temperate or colder region.
The Correct Lighting for an Indoor Lemon Tree
Many houseplants prefer bright, indirect light, but you have to remember the lemon tree isn’t a houseplant by nature. It needs brighter conditions still – I’m talking direct light.
How much direct light?
The more direct light, the better. At the very least, the tree requires eight hours of sunlight a day, and at most, 10 hours. This amount of direct light is especially important if you want to encourage your indoor lemon tree to produce lemons.
A south-facing window is a perfect place to position your new indoor addition.
Here are some indicators that your indoor lemon tree is begging for light: fresh green leaves shed from the tree for seemingly no reason.
You also won’t see the lemon tree flower. It’s those white, appealing flowers that later become lemons, so if they’re not appearing, or if they are but they’re dying, that’s a bad sign.
What do you do during those days when sunlight isn’t abundant? Or what about during the winter when you get maybe five or six hours of daylight at best?
The indoor lemon tree’s lighting requirements don’t change just because the seasons do. You can always augment the natural sunlight you do get with artificial light.
Plants cannot tell the difference, as light is light to them.
Soil and Pot Requirements for an Indoor Lemon Tree
If you have standard potting soil, set it aside for other houseplants, as the indoor lemon tree needs citrus tree potting soil mix.
You should be able to find citrus potting soil mix at any gardening supply store, including the store you purchased your indoor lemon tree.
If you bought the tree online, this specialty potting mix is also widely available there.
What is citrus potting soil mix?
It contains ingredients such as lime, worm castings, sand, perlite, and peat moss to provide the optimal pH, nutrient retention, drainage, and aeration for citrus trees like your indoor lemon tree.
I would recommend reading the ingredients list before you dump the soil into the pot. The potting mix should be amended already, so no need to add anything extra, but if yours by chance isn’t, then the above amendments apply.
What kind of pot does an indoor lemon tree require?
I recommend one made of glazed terracotta, clay, or ceramic.
These materials are usually ultra-porous on their own but glazing them reduces the porosity to such a degree that some water absorption occurs but not too much.
I always suggest adding a plastic pot liner if your pot is absorbing water too quickly.
The size of the pot is a very important consideration for your indoor lemon tree. If yours is a young, nursery-purchased tree, then a pot with a diameter of 12 inches is fine.
That pot will be the lemon tree’s home for the foreseeable future, as it will be another three or four years before you have to think of repotting the plant.
When that time inevitably comes, double the tree’s pot depth and width.
Temperature and Humidity Requirements for an Indoor Lemon Tree
Indoor lemon trees are picky about their temperatures, so you have to be too.
By day, temperatures of up to 80 degrees Fahrenheit suit this tree especially well. By night, temps of around 65 degrees are good, but the mercury can drop as low as 50 degrees and your tree won’t be under any duress.
That being said, lemon trees are not fans of drastic temperature shifts, nor do they like sudden blasts of cold or hot air.
I realize that in an office environment, you don’t always get a say over the thermostat settings, but as long as your cubicle is room temperature, your lemon tree should be fine.
What’s equally as important is positioning. Keep the lemon tree away from any refrigerators, freezers, fireplaces, drafty doors and windows, radiators, and return vents or forced air vents.
What about the indoor lemon tree’s humidity requirements? Those are none too special, really.
Lemon trees like humidity between 40 and 50 percent, which is not very moist at all.
If you don’t already have one, it’s a good idea to buy a hygrometer for home and office use. A hygrometer can measure the level of moisture in the air.
All buildings have a level of relative humidity, and it’s usually anywhere from 30 to 50 percent. Your home or office might already be humid enough for the lemon tree.
If not, then a humidifier is a good solution to make the air moister. You’ll appreciate it too, as you won’t have dry skin or sinuses.
Fertilizing the Indoor Lemon Tree
Feeding your indoor lemon tree fertilizer is a great way to encourage flowering that will later lead to the production of yummy yellow fruits.
Lemon trees need a lot of nitrogen, more so than phosphorus and potassium, so the fertilizer you use should contain a higher ratio of nitrogen such as a 2-1-1 or a 3-1-1 ratio.
Apply fertilizer when the tree’s active growing season begins, which is in the spring and specifically, late March.
You have the option to fertilize every two weeks, but I would say err on the side of caution and do it every three weeks to start.
The end of the fertilization period is August, as that’s when the indoor lemon tree’s growing season concludes.
Even if your lemon tree cultivar produces fruit all year long, you still shouldn’t fertilize it throughout the year. That can lead to negative consequences such as fertilizer burn.
A chemically burned lemon tree will likely bear no fruit–none that you’ll want to sink your teeth into, anyway–and could sustain damage that can hinder future harvests.
What type of fertilizer is best for an indoor lemon tree?
Organic liquid fertilizer with ingredients like fish emulsion, seaweed, or liquid kelp is one such option.
You can also use organic granular fertilizer.
For more information on using liquid fish emulsion as a fertilizer, I recommend reading my article, Is Fish Fertilizer Good for Plants?
You can also use natural fertilizers for your lemon tree made from organic items you may already own. For more on that, I recommend checking out my related article.
Indoor Lemon Tree Pests and Diseases
Insects can be beneficial to outdoor lemon trees, as they kickstart the pollination process that produces lemons.
Considering that lemon trees can self-pollinate indoors, you don’t want bugs.
The following insects especially are quite problematic for the health of your indoor lemon tree.
- Mealybugs: The piercing mouthpieces of mealybugs can easily suck sap from the indoor lemon tree, stripping it of its ability to bear healthy fruit. If the infestation is small and manageable enough, mixing water with 70 percent isopropyl alcohol in a spray bottle should do the trick. For larger infestations, chemical treatments might be required.
- Spider mites: The troublesome spider mites hide underneath a lemon tree’s leaves and weave webs. Signs your tree is infested can include grayish-looking leaves, a sandy texture, and discoloration such as yellowing. Use water and isopropyl alcohol or a touch of mild dish soap to take care of mites.
- Aphids: A common plant problem, aphids can reduce and even stop plant growth, which is not what you want when tending to an indoor lemon tree. To remove the nearly microscopic insects, use a garden hose to spray them off or apply some insecticidal soap.
- Leaf miners: Leaf miners include flies, sawflies, and moths. If you see them, it’s best to crush the miners when still in their larval stage so they can’t fly across your indoor garden unfettered. Pesticides can treat a more serious infestation but should be used as a last resort.
- Whiteflies: Although not always white, whiteflies are winged insects and a major nuisance in your indoor garden. You can remove whiteflies from your lemon tree and other houseplants by spraying with a gardening hose or using insecticidal soap.
- Scale insects: Scale insects can sometimes be tough to spot until they begin wreaking havoc on your houseplants. If you see scale insects on your indoor lemon tree, use 70 percent isopropyl alcohol or soapy water on a cotton swab or unused toothbrush.
Besides the above pests, the following diseases can affect lemon trees as well.
- Fungal root rot: As mentioned earlier, lemon trees are very susceptible to fungal root rot, which is often caused by overwatering. The roots die, eventually killing the whole plant. Trimming dead roots, repotting the lemon tree in fresh soil, and reducing watering is the only way the tree may survive.
- Citrus canker: A bacterial disease, citrus cankers will lead to premature fruit drop and canker sores all over the lemons and leaves. The fruits are still technically edible. The lesions that grow across the tree leak bacterial cells that can spread the disease to other citrus trees.
- Sooty mold: The sight of black sooty mold on your citrus tree is quite unsettling, to say the least. This is another fungal disease caused by pest infestations. The honeydew that some insects release will later create moldy spots on the citrus tree. Pruning the affected parts and reducing insect infestations will help.
- Anthracnose: Anthracnose is a fungal disease that can, in citrus trees, cause fruit stains, dying twigs and leaves, fruit decay, early leaf drop, and dieback. Wet conditions allow this disease to thrive. The only way to treat it is usually with a fungicide.
- Botrytis blight: Gray mold or botrytis blight is another disease that’s caused by overly warm and wet conditions. The fungal spores, despite the nickname of gray mold, can also be tan or brown. Quarantining the affected lemon plant and pruning the affected areas may allow for survival.
- Lemon scab: Common in some types of lemon trees, the Elsinoe fawcettii fungus causes lemon scab. Twigs, leaves, and fruit can be affected. Copper used as a fungicide can safeguard a citrus tree before it develops lemon scab.
Indoor Lemon Tree Common Problems
Is your indoor lemon tree not growing as perfectly as you had hoped for? It happens! Here are some common problems you might face and what to do about each.
Indoor Lemon Tree Losing Its Leaves
When a lemon tree drops its leaves prematurely, it can be caused by fungal or bacterial diseases, insect infestations, overly cold temperatures (which are under 50 degrees), lack of sunlight, or overwatering.
Assess the care areas of your indoor lemon tree to narrow down the culprit.
Indoor Lemon Tree Turning Yellow
What if you spot persistent chlorosis or leaf yellowing?
This problem too has several causes. A micronutrient deficiency–especially manganese, iron, or zinc–could contribute to this problem.
Check that your fertilizer contains enough micronutrients.
If not a micronutrient deficiency, the lemon tree could be experiencing a nitrogen deficiency.
Watering a lemon tree too frequently or infrequently can contribute to leaf yellowing, so those are areas to assess and change if need be. A lack of sunlight is another issue to fix.
Indoor Lemon Tree Turning Brown
For indoor lemon trees with brown instead of yellow leaves, check how much sunlight the tree is receiving and the intensity.
- Too much light or too intense light can cause the leaves to burn.
- An underwatered lemon tree will also develop crisp, brown foliage since it’s dehydrated.
- Too much sodium from an overapplication of fertilizer can also lead to this troublesome issue.
Indoor Lemon Tree Wilting or Drooping
If your lemon tree’s usually proud leaves begin to sag, it could be that the plant is lacking light. Temperature fluctuations can also cause the leaves to droop.