Indoor Planting
and Care
of Citrus Trees

1] TREE SELECTION: Shopping for trees

• AGE – Choose a tree that is already at least 2-3 years old, as it will produce fruit much sooner.
• DWARF TREES – Dwarf varieties are grafted onto special roots that limit their size and speed up fruiting. Dwarf trees produce the same size and quality of fruit but yield 50-60 percent less fruit. 
• LEAVES – Look for healthy trees with shiny leaves. 
• SIZE – Smaller trees are easier to plant and suffer less from transplant shock problems.  Even with dwarf varieties and regular pruning, most container citrus trees eventually measure near 6 feet tall.
• BLOOMING – Though it varies by variety, citrus trees tend to bloom in spring. Many species of citrus trees have beautiful flowers/blossoms.
• FRUITING – Fruits develop through the summer, and are generally ripe during the fall through the winter.

2] POTS and CONTAINERS

• CONTAINERS – Growing citrus in containers keeps them smaller 
• DRAINAGE – Use a pot with adequate drainage holes in the bottom, and have a saucer/tray below the pot.
• SIZE – Always allow ample space for proper root growth, but do not use a pot that is too large.  Pots that are too large cause excessive water moisture after watering, often resulting in root rot.

Larger pots will prevent top-heavy trees from tipping over, and heavier material types such as ceramic or clay improve stability.

• 5 gallon  12″ diameter,  7 gallon  14″ diameter
• 10 gallon  16″ diameter,  15 gallon.  18″ diameter
• 21 gallon  20″ diameter,  25 gallon  24″ diameter
• 45 gallon  27″ diameter,  65 gallon  32″ diameter

REPOTTING – If you’re going to re-pot your tree when you get it home, or when the tree increses in size,  go up by one pot size at a time.

MATERIAL TYPE – There are many different materials choices: Terra cotta, unglazed ceramic, plastic, fiberglass, wood, or resin containers

• Terra-cotta containers allow helpful air movement through the sides
• Lightweight plastic or fiberglass planters offer good alternatives is reduced weight is preferable.
• Dark colors, which absorb sun and generate heat, may be a problem for some locations (citrus prefer cool roots) Black plastic nursery pots have particularly high heat absorption rates. Heat is often destructive for root systems.
• Half whiskey barrels are a good option for larger citrus trees. 

MOVING POTS – Moving a citrus trees outdoors during the summer season is beneficial if practical. 

• Placing the tree pot on a plant dolly before filling with soil will facilitate easy relocation.
• Clearly, the heavier the pot, the more difficult it is to move
• Appliance dollies are helpful to move heavy pots

PLANT POT FEET – (Also called pot spacers and pot risers.)  Pots should not be sitting in pooled water that collects in the tray when watering.  in the It is best to use pot feet to allow air circulation at the base of the pot where the drainage holes are located. This prevents excessive moisture in the soil which can cause root rot.  There are countless different styles, sizes and materials available. Water trays are usually not necessary for pots located outside; however, in most cases, they are required indoors where there is potential for water damage to the floor.

3] PLANTING

• Citrus trees prefer their soil evenly moist. Potting soil mixes that stay too dry or too wet spell trouble. The water-holding crystals and wetting agent in this premium potting mix help keep soil moisture consistent as your citrus grows. 
• Citrus roots need air, so planting depth is important. 
• The area where the citrus tree trunk starts to flare out at its base should always be slightly exposed. As you fill your pot, leave plenty of room at the top for watering, and finish it off with decorative mulch, pebbles or moss. 
• Larger types of citrus trees (like lemons and grapefruit) may outgrow the container quickly and need to be repotted or have roots trimmed back.

4] SOIL

Citrus need well drained soil, so selecting the right potting mix is important. Commercial potting mixes with peat moss, perlite, vermiculite and compost are fine to use as long as the soil is light enough to drain water well.

When choosing soil for indoor citrus trees, it’s crucial to provide a well-draining and nutrient-rich environment for optimal growth. Here are some considerations for selecting the right soil mix:

• Well-Draining: Citrus trees prefer soil that drains well to prevent waterlogging, which can lead to root rot. Consider a potting mix specifically designed for citrus or create a mix using peat moss, perlite, or sand to improve drainage. Avoid a commercial mix that is designed specifically to retain moisture; excess moisture causes root rot. Many general potting soils for indoor plants also retain excessive moisture and must be avoided.
• Nutrient-Rich: Citrus trees require regular feeding to support healthy growth and fruit production. Choose a high-quality potting mix that contains essential nutrients like nitrogen, phosphorus, and potassium. You can also supplement with slow-release fertilizers or organic matter.
• pH Level: Citrus trees prefer slightly acidic to neutral soil pH levels (around 6.0 to 7.5). Test the pH of the soil periodically and adjust as needed with appropriate amendments; use peat in the potting mix to help keep the pH down.
• Aeration: Adequate aeration is essential for citrus tree roots to access oxygen. Incorporate materials like perlite or vermiculite in the soil mix to promote good airflow to the roots. Garden or native soil is NOT good as it  will not give the roots the air they need.
• Avoid Compaction: Ensure the soil mix remains loose and light to prevent compaction, which can hinder root growth. The potting soil should be light, fluffy, and drain well. Soil that is all organic matter (compost) will decompose too quickly and become compacted. To prevent compaction, gently loosen the soil surface periodically to encourage air circulation. 
• Moisture Retention: While good drainage is essential, the soil should also retain some moisture to keep the roots hydrated. Consider adding coconut coir or peat moss to help retain moisture without waterlogging the roots.
• Soil Mix: A good soil mix is: one-third sterile potting soil,  one-third drainage material: perlite or vermiculite, small gravel, sand, pumice, expanded shale, and one-third moisture retention material: peat or tree bark. Perlite and vermiculite are good for both drainage and water retention. A good potting solid mix is probably good for 6 months before it requires fertilizer.
• Mycorrhizae: The addition of mycorrhizae to the potting soil will help get nutrients to plant roots.
• Commercial Blends – potting sold blends specifically for citrus trees are available. Also soils designed for cacti and succulents are often used for citrus trees.
•  
• “The use of peat is controversial since the harvesting of peat moss from peatlands (which includes unique habitats such as bogs and fens) degrades these peatlands. Peatlands are home to a diverse range of plant and animal species. Peat also has a very slow accumulation rate, as little as 1mm per year, so they take a long time to regenerate. Peatlands are also carbon sinks, constituting 3% of the world’s surface but storing up to 30% of the carbon sequestered in the soil. The removal of the layer of CO2 absorbing plants releases CO2 into the atmosphere, contributing to climate change.” (Wiki)

5] LIGHT

• Citrus trees need 6 to 8 hours of bright light. Look for a location that receives morning sun and afternoon shade. Placing trees near southern or southwest windows works well. 
• Citrus trees prefer direct sun for at least part of the day.
• If your trees do not get at least 6 hours of direct light a day, LED grow lights can provide supplementary lighting. Make sure not to place the light too close to the plant or it may burn the foliage. Position your grow light about 18 inches above the canopy for best results. During the winter, keep the lights on for about eight hours a day. The lights should be turned off in the evening as too much light is a problem. Grow lights will be needed from October to March in northern areas.
• Citrus trees can survive in lower light conditions, but the ability to produce flowers and/or fruit will be less.

OUTDOORS DURING SUMMER

• During the summer, put citrus plants outside to take advantage of better light.
• Let the plants acclimate to sunny conditions by putting them in the shade of a tree or the north side of the house for the first several days. Make sure they have plenty of direct light once they’re used to being outside.
• Get them used to lower light at the end of the summer by keeping them in a shady place for a week or so before bringing them back indoors.

6] FERTILIZER

Fertilizing indoor citrus trees is essential to support their growth, fruit production, and overall health. Since regular watering can leach nutrients, it is important to provide a source of fertilizer for indoor plants.

• Choose the Right Fertilizer: Select a fertilizer specifically formulated for citrus trees or use a balanced, slow-release fertilizer suitable for fruit-bearing plants. Citrus plants are heavy feeders. They need liberal quantities of nitrogen; use a high-nitrogen fertilizer. The most important thing is to be sure to use a complete fertilizer that contains nitrogen, phosphorus, and potassium (NPK). You may also need to supplement with trace minerals. Look for a fertilizer with a higher potassium content to support fruit development.
• Timing: Fertilize indoor citrus trees during the active growing season, typically in spring and summer. Avoid fertilizing during the dormant winter months when growth slows down.
• Frequency: Follow the manufacturer’s instructions for application rates and frequency. In general, it’s recommended to fertilize indoor citrus trees every 4-6 weeks during the growing season. Err on the side of caution and avoid over-fertilizing.
• Application Method: Apply the fertilizer evenly around the root zone, avoiding direct contact with the trunk or foliage. Water the tree after fertilizing to help distribute the nutrients into the soil.
• Monitor Growth: Pay attention to the growth and appearance of your indoor citrus tree. If you notice slow growth, pale leaves, or poor fruit development, it may indicate a nutrient deficiency or improper fertilization.
• Nutrient Needs: Citrus trees require a balance of essential nutrients, including nitrogen, phosphorus, potassium, and micronutrients. Consider using a citrus-specific fertilizer that meets these requirements.
• Organic Options: If you prefer organic fertilizers, look for natural options such as compost, fish emulsion, or seaweed extracts. These can provide nutrients to the soil and improve soil structure over time.
• Supplements:  Supplement with kelp- or fish-based products. Supplementing with a liquid feed is recommended if you notice yellowing foliage, which can be a sign of nitrogen deficiency.
• Slow Release Fertilizer: A granular slow release fertilizer will provide best results.  

7] WATER

Proper watering is crucial for the health and vitality of indoor citrus trees. Here are some essential tips for watering indoor citrus trees effectively:

• Check Soil Moisture: Before watering, check the soil moisture level by inserting your finger about an inch into the soil. If it feels dry to the touch, it’s time to water.
• Watering Frequency: Indoor citrus trees generally need regular watering, especially during the active growing season (spring and summer). Water when the top inch of soil feels dry, but avoid overwatering, as citrus trees are susceptible to root rot.
• Deep Watering: When you water, make sure to thoroughly soak the soil until water drains out of the bottom of the pot. This helps encourage deep root growth and prevents water from pooling around the roots.
• Drainage: Ensure that the containers have adequate drainage holes to allow excess water to escape. Standing water can lead to root rot and other issues.
• Humidity: Citrus trees appreciate a humid environment. You can increase humidity around the tree by misting the leaves with water or using a humidity tray filled with water and pebbles.  
• Water Quality: Use room temperature water to avoid shocking the roots. If your tap water is high in minerals or chlorine, consider using filtered or distilled water.
• Adjust for Season: During the dormant season in fall and winter, reduce the frequency of watering as the tree’s growth slows down. Allow the top inch or two of the soil to dry out between waterings.
• Monitor Plant Response: Watch for signs of overwatering, such as yellowing leaves, wilting, or mold. Adjust your watering schedule based on the tree’s needs and environmental conditions.

Water: Never let pots dry out completely, but avoid overwatering. Allow your potting soil mix to dry slightly about 2 inches deep, and then water thoroughly. Test your potting mix by hand or use a soil moisture tester, available in home and garden stores.  During active spring and summer growth, container citrus may need extra watering. In winter, water just enough to keep soil moist.

• Use a water meter
• Check your containers frequently; citrus in containers dry out more quickly than citrus in the ground. Dip your finger into the soil an inch or so, and if it feels dry, it’s time to water. Use a moisture meter to give you a more exact idea of how wet the roots are.
• Each time you water, water thoroughly making sure the water is being absorbed and not just draining out the hole in the bottom. If this happens to your soil, gently dig in the soil with a garden spade; don’t turn the soil over, just loosen it. Next, sprinkle the surface lightly with water. After several sprayings, the soil should begin to break up and loosen allowing more water to be absorbed. Adding a 1″–2″ layer of mulch can help prevent this in the future. 
• Pay attention to your citrus tree. Your plants will tell you if their water needs aren’t being met. Leaves that are wilted and then perk up after watering are a sign of roots that have been allowed to dry out too much. Yellow, curled leaves that don’t perk up after watering may mean they are getting too much water. Citrus roots like moist but not soggy conditions.
• Another key to successfully growing citrus in pots is appropriate watering. It is important that the soil should remain moist, without ever becoming waterlogged.
• The exact amount of water required depends on a number of variables, including the size of the container, type of potting mix, air temperature, and humidity.
• The most important thing is to water regularly to keep the soil moist, but never to let it become overly saturated.
• It is better to do infrequent deep waterings rather than frequent shallow waterings. Let the soil dry to a couple of inches deep, and then water thoroughly until water seeps out of the drainage holes in the bottom of your pot.
• During the spring and summer when growth picks up, trees may need daily watering. In the winter when plant growth slows, water only enough to maintain soil moisture.
• Look for yellowing or curled leaves, which could be a sign of over watering.
• Regular watering is key. Adding pretty, decorative mulch (such as pebbles or moss) will help reduce evaporation and retain moisture at the critical surface-root zone. But keep in mind that your tree’s potting soil should be kept on the dry side of moist, particularly in winter, to prevent fungal infections and root rot. Using a water meter (available at most garden centers) to measure the soil’s moisture level will help. 
• Keep soil to be on the dry side of moist. They don’t want to dry out completely, but they won’t like too much water. A moisture meter, available at our garden centre, is your friend when it comes to these picky trees. Check a few different spots around the pot, and once your soil meter is averaging a 2-3 measurement, its time to water. Water until it comes out the bottom into the tray. Leave the water in the tray for 12 hours, and then empty any excess (a turkey baster is a great way to remove excess water without having to move the tree).
• Overwatering is the number one killer of citrus. The soil needs to dry out between deep waterings: A moisture meter ($15, The Home Depot) should read three fully inserted in the soil. When your plant needs more hydration, drench its soil until water runs from the pot’s drainage hole. Suction up any water in the saucer with a turkey baster to prevent a soggy bottom and root rot.
• Dropping green leaves and dying twigs are root rot symptoms (due to overwatering). If you suspect this problem, you’ll need to intervene.Put the tree on its side.
• Pull the tree gently from the pot, including the soil. If roots disintegrate, they’ve rotted.
• Immediately remove soil and damaged roots, wash the pot well with soap and water, and replant in fresh potting mix.
• Water, then allow the soil to dry out before watering again.
• New growth will appear in a few months if the process goes well. If not, it’s probably time to toss out your plant.
• There are numerous self watering systems available at hardware stores or Amazon.

8] PRUNING

• When pruning citrus in containers, prune for 3 things: 1) Prune suckers below the graft union; they sap energy from the tree and do not produce fruit.  2) Prune dead branches. 3) Citrus can also be pruned to keep the citrus a desired size and/or shape. Avoid pruning lower branches.
• Pruning: Regular pruning helps limit container citrus tree size and promotes bigger, better fruit. Don’t be shy about pruning potted citrus — just wait until trees flower and set fruit so you don’t accidentally prune away your treats. Trim off thorns and any roots or shoots that form near the surface of your potting soil mix.
• If any young green shoots are present below this graft area, prune them off, as they will use up valuable nutrients to grow but will not produce fruit.
• While pruning is not necessary for healthy growth and fruit production, it is useful to keep indoor trees compact and mobile.
• Trees can be pruned at any time during the year except when blooming and developing fruit, as this diverts energy away from fruit production and into new foliar growth.
• Start by taking note of the general shape of the tree, looking for areas that are off balance or branches that are damaged or broken.
• Use clean, sharp pruners to make cuts, always with the blade pointing towards the tree to reduce potential damage.
• You can regularly trim growing tips to maintain your preferred shape and size. For a neat and compact shape, look for new shoots and shorten them back to about half of their length, cutting just above a leaf.
• You can also remove dead wood and thin out inside branches to let light penetrate to the center, and promote good air circulation.

9] PESTS

When trees summer outside, pests can seize the opportunity and even hitch a ride into your home come fall. Citrus-loving insects, such as thrips and spider mites, can cause fruit and leaf damage to your tree. If pests strike outdoors, apply a light, even layer of Sevin Sulfur Dust. The dust starts killing listed pests immediately upon contact and will not harm your citrus tree.

• Scale, whitefly and spider mites are some of the more common pests of citrus.
• Make sure the leaves are kept clean by periodically washing them.
• Pay special attention to the undersides as well as the tops of leaves.
• To treat insects, check garden centers for products currently approved for use on houseplants.
• Contrary to what you might expect, pests can become especially troublesome with indoor growing. Since there are not many natural predators indoors to keep pests in check, populations can grow rapidly and cause significant damage.
• Aphids: Trees can be susceptible to black citrus, cotton, and spirea aphids. These pesky little insects can range in color from green to yellow or black. They feed on the buds and undersides of leaves, causing foliage to curl. Aphids also produce a sticky secretion called honeydew, which can cause a buildup of sooty mold on foliage.
• Mealybugs. These flat, oval-shaped insects are pink with a white wax coat. They lay their eggs on the fruit, leaves, and twigs of citrus trees. As a result, they make the tree less vigorous. And they also produce honeydew, which can lead to sooty mold.
• Whiteflies. The larvae of these small, white, winged insects feed on the undersides of leaves, causing foliage to turn yellow and drop. Like aphids and mealybugs, whitefly larvae also excrete honeydew that can cause sooty mold.
• Mites. These tiny pests are a common problem for indoor plants. They cause yellowing and dropping of foliage, as well as discoloration and shriveling of fruits.
• If you are able to move plants into the bathtub or onto the porch, a strong spray of water can often be enough to remove pests, including any honeydew and accompanying mold. Make sure to spray the undersides of leaves.
• You can also make a homemade insecticidal soap by filling a spray bottle with water, a couple of teaspoons of mild biodegradable soap, and a teaspoon or two of vegetable oil. Spray the foliage every few days, as long as the infestation persists.
• A spray of cayenne or jalapeno pepper and garlic mixed with water can also deter pests. A word of warning, however: this may make your house smell a bit strong for a while! Be sure to wear gloves when working with hot peppers and protect your eyes when you apply the spray.
• To prevent insects from getting out of control, keep citrus away from other houseplants, vents, doors, and window screens, and always give them a thorough rinse before moving plants indoors for the winter.

10] DISEASES

When growing citrus in containers indoors, the trees aren’t as prone to disease as they are outdoors, but there are a couple of things to be aware of:

• Sooty Mold: Sooty mold is a fungus that can impact indoor citrus trees. Caused by infestations of sap-sucking insects, sooty mold is characterized by a black powdery coating on leaves and twigs. The good news is, it is usually not a huge problem in terms of plant health, though it is not the prettiest. In severe cases, it can block light, stunt growth, and cause yellowing of foliage. More than anything, the presence of sooty mold is a sign of an underlying pest issue. Get rid of the insects and you will prevent new mold from being introduced. Be sure to wash off what’s already there, after dealing with an infestation.
• Root Rot: Usually caused by fungi from the Phytophthora genus, root rot is often a result of overwatering or allow your tree to sit in waterlogged soil. Pot size is also a consideration – if small trees are planted in a pot that’s too big, this can lead to excess moisture remaining in the soil. Keeping trees healthy by watering them well and providing adequate sunlight will also help to avoid stressing your plants, making them more readily resistant to problems as a result.

11] TEMPERATURE/HUMIDITY

• Temperature: Normal household temperatures suit citrus fine, and most withstand brief, near-freezing cold. However, avoid placing your tree near drafts or heating and air conditioning ducts. Container citrus can summer outside, but keep them inside until frost danger passes in spring. Then move them gradually, so they acclimate over several weeks, or they may drop their ripening fruit. Move them back inside before fall frost strikes.
• The safer alternative is to move plants under cover when it turns cold. Frost-free greenhouses work well, or bring them inside into a conservatory, sunroom or onto a bright windowsill. Prioritize the brightest positions for your citrus to minimize leaf drop. Growth will slow considerably either way –from the cooler temperatures, poor light levels, or both.
• While citrus can’t abide soggy soil, the air in our modern, well-insulated homes tends to be a little too dry for comfort. Keep indoor citrus well away from heat sources, which dry out the air and create a stressful environment at what should be a restful time of year. Raise the humidity around plants by standing pots on trays of pebbles, part-filled with water so pots remain out of the water. As the water evaporates it will help to create a more humid atmosphere.
• Plants won’t appreciate wild swings in temperature either, so ventilate greenhouses and sunrooms on sunny days when the mercury can quickly soar to spring-like heights. Then, when spring proper arrives, acclimatize plants to the outdoors over the course of two weeks, setting them out in their sunny summer quarters once the final frosts are done.
• Citrus is best grown in air temperatures between 55 and 80°F. Keep in mind that ideal temperatures vary between species.
• In order to flower, citrus requires 5 to 10 degrees of difference between day and nighttime temperatures, so turn your thermostat down a few degrees before bed.
• When the weather warms up, you can move plants outdoors during the growing season to give them access to natural light. Bring them outside once the air temperatures are consistently above 50°F, transitioning them to their new conditions over a period of a couple of weeks. Gradually move them from a partly shaded spot to one with full sun, eventually setting them in the sunniest spot you can find. Provide protection from wind, and keep the pots in their saucers to maintain good drainage.
• Find a warmer microclimate in your yard, such as near a building where there might be some heat reflected from a walkway, driveway, or porch.
• It is especially important to avoid any abrupt changes in light exposure or temperature. If you transition them too quickly, leaves could become sunburned and flowers and fruit may drop.
• Move trees back indoors before nighttime temperatures drop into the 40s.
• Keep citrus trees in areas with even temperatures. They will do best when the temperature stays between 18-25˚C. They really don’t like drafts, whether hot or cold, so keep them away from doors and heat registers. They also don’t like cold water, so let your water sit at least overnight so it can warm up to room temperature.
• Citrus trees also like moist air. Positioning your plant near a humidifier or regularly misting the leaves with a spray bottle will help keep the foliage looking its best in the dry winter months.
• Avoid exposing your plant to hot or cold blasts of air. Never place it beside a heat source or near an exterior door. In warm weather, citrus trees prefer life outside. If you don’t have outdoor space and have the right conditions indoors, you can keep them thriving year-round if you’re hypervigilant about care.

12] POLLINATION

You may have flowers, but still have difficulty getting fruit to form on your citrus plant. This may be due to lack of pollination.

• Insects pollinate citrus outside. Since these are not usually present in the home, shake the flowers gently or flick them with your fingers to spread pollen from flower to flower.
• Although they are self-fertile, when grown outdoors, citrus trees will be pollinated by insects or wind. It’s a good idea to hand pollinate your plants.To do this, just take a Q-tip or small paint brush and move from flower to flower, brushing the center of each one.
• If this tender loving care results in flowers, they may not develop fully into fruit. This is probably due to lack of pollination, which you can assist with. Shake, flick, or brush with a cotton swab or artist paintbrush gently to distribute the pollen from flower to flower and encourage fruiting. Additionally, moving the plant outdoors to a sunny, protected area will stimulate blooming.
• When pollination is a success, fruit will develop and take a few weeks to ripen. It is fairly common for smaller, young fruit to drop off shortly after formation due to ineffective pollination or less than desirous environmental condition