Citrus Update


Trovita orange tree

December 16, 2018: This Advance Spectrum MAX 720 watt LED growlight fixture has 240 individual leds. It's on 12 hours a day and provides enough light for 2 citrus trees.

Trovita orange tree

December 9, 2018: Calamondin orange tree loaded with fruits in various stages of development. It is growing in a 10 gallon pot.

Prunings provide mulch for tree.

December 9, 2018: Prunings add organic matter to soil.

Trovita orange tree

December 9, 2018: Semi-dwarf Trovita sweet orange tree growing in a 7 gallon pot.

Trovita tree decline

October 7, 2018: Calamondin orange tree with fall crop of ripening oranges.

Calamondin fruit harvest

February 11, 2018: Calamondin fruit harvest.

Calamondin tree bearing fruits

December 15, 2017: Calamondin orange tree with over 60 fruits in various stages of development. This tree is also suffering from nutrient deficiencies which was later corrected.

Calamondin and Trovita Orange

September 9, 2017: Calamondin on the left loaded with fruit and Trovita on the right with 1 developing fruit.

Trovita Orange

August 25, 2017: Trovita orange tree first growth flush since planting.

Calamondin and Trovita Orange

August 12, 2017: Calamondin and Trovita orange growing under led lights.

Trovita orange in 7 gallon pot

August 12, 2017: Trovita orange transplanted to 7 gallon pot.

Trovita orange in shipping box

August 11, 2017: My 3 year old Trovita orange tree arrived from the nursery.

Calamondin Orange

May, 2016: My 2 year old Calamondin orange tree arrived from the nursery.

Calamondin Orange


June, 2016: Calamondin growing in 5 gallon pot.

Calamondin Orange


July, 2016: Calamondin growing well.

Calamondin Orange


December 27, 2016: Lots of new growth on tree.

Calamondin Orange


December 27, 2016: The first fruit to develop on young tree.

Calamondin Orange growing under LED grow light.


August 1, 2017: Calamondin orange flowering and fruiting under new LED grow light.


Buying a Citrus Tree
Potted citrus trees can be purchased at some garden centers in non-citrus areas; however, buying trees from a reputable citrus nursery that certifies its nursery stock free of pests and diseases is the best way to go. Before making a decision to buy a tree, make sure you have the right growing environment for it. It is very important because not all citruses are the same.


Best Varieties for Beginners
There are many varieties of citrus trees that do well under indoor cultivation. The following are the best for beginners because acid fruits have a lower heat requirement for ripeness than sweet fruits.
Calamondin Orange
This plant is not a true orange. It is very productive and cold tolerant. The fruit is about 1.5 inches (3.8cm) in diameter, very juicy, highly acidic, with few seeds. The peel is deep orange, thin, sweet and edible. The fruit can be used to make marmalade and the juice can added to water and sweeten to make a tasty fruit drink. Fruit matures in about 8 months and holds well on tree. A varigated form is also available. Highly recommended for its toughness, ornamental beauty, and medicinal properties.
Improved Meyer Lemon
This plant is a lemon hybrid. The tree is almost thornless, productive, and blooms frequently. Flower buds are tinged with purple. The fruit is small to medium size, mildly acidic, juicy with excellent flavor. The rind doesn't have the rich lemon potency of a true lemon. Highly recommended.
Eureka Lemon
The tree is vigorous and productive with few thorns. It bears loads of very juicy, acidic fruits that are high in vitamin C. A true lemon with excellent flavor.
Lisbon Lemon
The tree is vigorous, productive and thorny with a spreading growth habit. It is more tolerant of adverse conditions than Eureka. It bears a huge crop of very juicy, acidic fruits that are high in vitamin C. A true lemon with excellent flavor. Highly recommended.
Varigated Pink Eureka Lemon
The tree is less vigorous and productive than the regular Eureka lemon. The pulp has a pink color with a mild acidity. Highly recommended for its ornamental beauty and usual fruit.
Persian or Bearss Lime
This tree is vigorous with few thorns. It bears fragrant blossoms and fruit all year. The fruit is medium-small, acidic, and very juicy. Fruit is usually picked green, but it's yellow when ripe. Mature fruit doesn't hold well on tree. Highly recommended.
Eustis Limequat
This plant is a lime x kumquat hybrid. The tree is very productive and cold-tolerant. The fruit is medium-sized and has the flavor and aroma of a lime. Mature fruit holds on tree for a month or more.
Nippon Orangequat
This plant is a hybrid between a mandarin and kumquat. The tree is productive and very cold tolerant. The fruit is small, few seeds, juicy, acid with a sweet rind.


Planting
A one year old citrus tree should be started in a 7 to 10 gallon pot. A two to three year old tree should be started in a 10 to 15 gallon pot. If you purchased a citrus tree that came in a pot, carefully slip it out of the container and gently massage the rootball before planting. Any premium potting soil mix that is well-drained, moisture retentive with no wetting agents added, and a pH between 5.5 and 6.5 will suffice. I'm currently using Roots Organic Original potting soil mix. It's an excellent soil mix for growing citrus trees in containers.
Soil amendments I usually add to my potting soils if needed are: horticultural pumice or Growstone GS-2 soil aerator or shredded pine bark. I also add some Azomite rock dust and worm castings.


Watering
Knowing when to water is the key to growing potted citrus trees successfully. The soil should be kept moist, not wet. Water only when the top half of the soil is moderately dry. When you do water, may sure it is thorough. The water should drain into the saucer and emptied. During hot weather, you may have to water once or twice a day. During cool weather, water less often.
Water quality is an important thing to consider when growing citrus. If your tap water is hard (alkaline), it will cause certain elements in your soil to become unavailable to the plant. Add 1 teaspoon of vinegar to 1 gallon of water to lower pH.


Fertilizing
Citrus trees are heavy feeders and potted trees are especially prone to nutrient deficiencies due to limited root space and regular waterings. An adequate fertilizer program is needed for citrus trees to grow and produce well. During the flowering and fruiting cycle, it is crucial to maintain a steady supply of nutrients. Use an organic citrus fertilizer which supplies macronutrients (nitrogen, phosphorus, potassium, magnesium, calcium) and micronutrients (iron, zinc, copper, manganese).
My organic fertilizer program consist of using bat guano and camelina meal for nitrogen, rock phosphate for calcium and phosphorus, and sulpomag for potassium and magnesium. Azomite rock dust supplies many trace elements. Greensand supplies long term iron availability as well as potassium and trace elements. Worm castings and compost are excellent for improving the soil structure. Kelp meal and seaweed extract also supply trace elements and many vitamins, enzymes, and hormones to enhance growth. Epsom salt (magnesium sulphate) is applied monthly during the fruit development stage.
For more information on citrus nutrition, please check out citrus nutrition and fertilization by the University of Florida IFAS Extension Service.


Light
Having adequate light indoors is absolutely essential for good growth and fruiting. Citrus trees require a minimum of 5 hours of direct sunlight, though 10 to 12 hours is ideal. Supplementary lighting can be used to make up the difference. There are many different lighting systems available on the market. A full spectrum LED lighting system offer the best quality light for successful flowering and fruiting of indoor citruses. More information about lighting systems can be accessed on the online garden suppliers page.


Temperature/Humidity
Citrus trees require a warm, frost-free environment to grow and produce well. They can withstand temperatures over 100F (37.5C), however, growth is sharply reduced below 55F (13C). Indoor growers should provide a subtropical growing environment for their trees if possible. A temperature of 75F to 90F (24-32C) for spring and summer is ideal. During the fall and winter, a temperature range of 60F to 70F (16-21C ) is ideal. In either case, the low temperature should not go below 45F (7C).
Some citrus trees are more cold tolerant than others. Container grown trees are less cold hardy than trees grown in the ground. As a general rule, potted trees shouldn't stay outside below 50F (10C). The most to least hardy citruses are: trifoliate orange, kumquat, mandarin, sour orange, sweet orange, pummelo, grapefruit, lemon, lime, and citron.
The indoor relative humidity should be in the 45% to 50% range during the heating season. A room humidifier should be used to maintain humidity levels and a hygrometer should be used to monitor it.
When citrus trees are grown partly or exclusively indoors, a circulation fan is highly recommmended. A ceiling fan or oscillating fan keeps air flowing around your trees and help distribute heat and humidity through out the room.


Acclimating Citrus
When you are ready to move your citrus tree indoors for the winter or outdoors for the summer, it needs to be acclimated to its new environment to avoid a severe shock. The indoor/outdoor temperature should be as close as possible for the transition move. Before moving citrus indoors, it should gradually be shaded over a period of 3 weeks. When tree is moved outdoors, place it under a shade cloth, a lath shade structure, or in an area that receives only the weak morning or evening sun. Over a period of 3 weeks, gradually introduce to more sunlight. After the tree has been properly acclimated, place it in a sunny, southern location sheltered from strong winds. The ideal spot is one that receives sunlight from sunrise to sunset. Before the permanent move outdoors, the temperature should be moderately warm and consistent over a 2 to 3 week period.


Growing Sweet Citrus
It takes resourcefulness and patience to grow sweet citrus in a cold climate, but it can be done quite successfully. Choosing the right variety is an absolute must! Citrus varieties that grow and produce well in the mild coastal regions of California are ideal candidates for indoor citriculture.
Sweet citrus demands a lot from its environment in terms of heat required for growth and ripe fruit. Since a long growing season is required for optimum growth and performance, a greenhouse is needed to provide extra growing heat. A simple greenhouse can be made out of a 5 foot (1.5 meters) tall wire fence. Stake the cage and wrap it with clear plastic. It should be adequately ventilated to prevent overheating, and the pot should be shaded to keep roots cool and reduce water needs. Greenhouse


Sweet Citrus Varieties
I recommend the following varieties for advanced indoor citrus growers who enjoy a challenge. I selected these varieties based on their heat requirements: 75F to 90F (24C to 32C), fruit quality, and adaptability. All varieties are available on dwarfing rootstock.
Valencia Orange
This variety is the standard among juice oranges in the world. It is widely adaptable from cool coastal to hot desert areas. The tree has a vigorous growth habit, and the fruit is medium-large, very juicy, sweet, with few or no seeds. It takes 14 to 18 months to ripen with an orange or greenish-orange rind. Mature fruit can be held on the tree for a few months.
Washington Navel Orange
This variety is the standard among fresh eating oranges. The tree is moderately vigorous, productive, and sensitive to changes in temperature. The fruit is large, richly flavored, sweet, juicy, and seedless. It takes 10 to 13 months to ripen with a deep orange rind. Mature fruit holds on tree a few weeks after ripening. Best grown in a cool greenhouse. Highly recommended for its fruit.
Trovita Orange
This California orange variety is definitely worth mentioning. I have experience growing this variety, and it makes an excellent houseplant. The tree is vigorous and productive with an upright growth habit. The fruit is medium-large, very sweet, juicy with few seeds. It has a rich, orangy flavor and aroma. It ripens in 10 to 14 months. Mature fruit holds well on tree. Highly recommended for its adaptability, high quality fruit, and low heat requirement to sweeten fruit.
Owari Satsuma Mandarin
The tree is slow growing, very cold tolerant, and capable of tolerating unfavorable conditions. The fruit is medium-small, seedless, juicy with a mild, sweet flavor. It ripens in 10 months with a bright orange rind. Mature fruit holds on tree about a week before deteriorating on tree, however, it stores well in the refrigerator. Highly recommended for its tolerance to adverse conditions and fruit.
Kinnow Mandarin
The tree is vigorous and productive with an upright growth habit. When I tasted the fruit from this tree, it was richly-flavored, very juicy, seedy, and sweet! The fruit ripens in 12 to 15 months with a yellow-orange rind. Mature fruit holds on tree a few weeks. Best grown in a cool greenhouse. Highly recommended for its fruit.
Clementine Mandarin
The tree is slow growing with an attractive weeping habit. The fruit is about 2 inches in diameter, juicy, and sweet with few or no seeds. Fruit ripens in 9 to 12 months with a bright orange rind. Mature fruit holds on tree a few weeks.
Oroblanco Grapefruit
This white-fleshed grapefruit variety is actually a cross between a grapefruit and a pummelo. I have tasted the fruit, and it is superb! The fruit is large, very juicy, seedless, pleasantly flavored, low acid, and sweet like an orange. It ripens in 10 to 13 months with a pale yellow, very thick rind. Mature fruit holds well on tree. Highly recommended for its fruit.
Moro Blood Orange
The tree is very productive and nearly thornless. The fruit is small to medium size, juicy, sweet, rich, with an exotic flavor. Flesh color is a deep red at maturity. Fruit ripens in 12 to 15 months with a reddish-orange rind. Best grown in a cool greenhouse.
Cara Cara Navel Orange
The tree is moderately vigorous and productive with a compact growth habit. The fruit is seedless, sweet, and juicy. The flesh has a light red color with an orange peel. The fruit ripens in 12 to 14 months. Highly recommended for its ornamental beauty and fruit. Best grown in a cool greenhouse.
Gold Nugget Mandarin
The tree is a patented variety. It is vigorous and productive. The fruit is richly flavored, very juicy, seedless, sweet, and holds well on tree. The peel has a bumpy texture. Fruit ripens in 12 to 14 months. Best grown in a cool greenhouse.


Growth Habit
Citruses make beautiful evergreen trees. They grow with an upright, spreading, or weeping habit and some have thorns adjacent to the leaf axils. They have 4 to 5 growth cycles or flushes a year. Trees grow most vigorously when it is warm and humid. They go into a dormant-like state when the temperature is around 50F (11C) or when there isn't enough water available for growth.


Flowering and Fruiting
Most citrus varieties are self-pollinating, however, a few do require cross pollination from another variety. Under indoor cultivation, citrus trees tend to bloom somewhat on a regular basis. A winter rest period is recommended especially for fruit bearing sweet citrus trees. Vigorous growth and flowering during the winter will divert energy away from developing fruits. To rest trees cut back on fertilizer, watering, and lower room temperature.


Pruning
Citrus trees store their food in their leaves; therefore, the amount of leaves removed will have a direct impact on the tree's fruit-bearing capacity. Prune only to remove dead, broken, diseased, or crossed branches. Remove all growth coming from below the graft union. For size containment, use thinning to control desired height and spread. Use heading to fill in gaps within the tree.


Root System Management
Potted citrus trees can be productive for many years with a healthy and thriving root system. Root system management involves 5 key areas: soil moisture, soil aeration, soil pH, drainage, and root pruning.

  • Soil moisture: Monitor soil moisture by digging into soil along the pot's edge a few inches down. The soil should be moderately dry half way down before watering. Use a moisture meter. See link below.

  • Soil aeration: Use soil amendments like horticultural pumice stones, Growstone GS-2 soil aerator stones or shredded pine bark to improve soil porosity. Perlite is another popular amendment that is often used in many potting mixes, however, it tends to rise to the top and breaks down over time.

  • Soil pH: soil pH and moisture meter to check pH range (5.5 to 6.5 is ideal). Without the proper pH, certain minerals become unavailable to the roots.

  • Drainage: Drill more drainage holes in the pot's bottom. The pot should also be raised above the drainage saucer about an inch or so to facilitate faster drainage and promote air circulation underneath pot.

  • Root pruning: Pruning should be done when the tree is not actively growing. Shave 1" off the sides of the rootball with a long serrated knife and repot. The should be done at least once a year or when vigor declines.



  • Propagation
    Citrus can be propagated by seeds or leaf cuttings. It's fun to watch a seed sprout and develop, through care and training, into an attractive evergreen tree. Take seeds from a fruit and rinse them removing the adhering flesh. Plant seeds in a small pot with a professional soil mix. They should be planted an inch deep. Keep the pot in a warm, bright location. Don't let the soil dry out. About 3 to 4 weeks later, there should be signs of growth.
    Propagating citrus from a cutting insures varietal integrity. Take a four inch cutting from a recently matured growth flush. Cut just below a leaf bud and remove half the leaves. Dip cutting in a rooting hormone solution and plant in a sterile rooting medium. Keep soil moist and humidity high and cutting will root in about 4 weeks. Bottom heat is recommended. If you take a cutting from a dwarf tree, it will not develop into a dwarf. Dwarfing occurs if you graft a selected variety onto a dwarfing rootstock.


    Grafting
    If you want to grow two or more citrus varieties on one tree, then grafting is your answer. The simplest grafting technique is T- budding. Check out grafting techniques at your local cooperative extension office or horticultural websites.


    Pests and Diseases
    Indoor citrus growers have far fewer pests and diseases to deal with than commercial citrus growers. Spider mites, aphids, mealy bugs, and scales do occasionally attack citrus while indoors and outdoors. For small infestations, use a spray bottle filled with mild, soapy water. Thoroughly wash down tree and repeat once a week. For medium to heavy infestations, use neem oil solution.
    Indoor citrus growers need to create their own pest management program. As a start, check the leaves, especially the undersides, at least once a week. Any new plant arrival should be quarantined and monitored for pests.
    Diseases that show up on indoor citruses are sometimes due to incorrect cultural practices. Overwatering can lead to root rot. Fungal leaf problems can develop when leaves stay wet without adequate air circulation to dry them quickly.


    Troubleshooting Potted Citrus Trees
    Symptoms Probable Causes Solutions
    Leaves change color and drop, flower buds drop Too much light or not enough, underwatering, overwatering, low humidity, sudden temperature change Gradually move plant to brighter location, water only when the top 2" (5cm) of soil is moderately dry, increase humidity, keep growing environment stable
    Leaves turn pale with green veins Interveinal chlorosis caused by a micronutrient deficiency Use fertilizers that contain chelated trace elements
    Mature leaves turn yellow with green midrib Yellowing caused by a magnesium deficiency Use 2 tsp of Epsom salt/gallon of water
    Fruit drops off before maturing Low humidity, water stress, sudden temperature change, natural thinning of fruit Buy a humidifier to increase humidity, water soil thoroughly especially during warm temperature.
    Leaves pucker, distort, or turn pale before dropping Environmental shock, insect infestation Keep environmental conditions stable, check for insects on leaves and stems with a magnifying glass.
    No flowers on healthy plant Plant was grown from seed, not of fruit-bearing age, a rootstock sucker has taken over, pruning reduces fruitfulness Seed grown plants can be unpredictable, grafted dwarf trees take 2 to 3 years to start bearing fruit, do not prune
    Fruit doesn't ripen Inadequate heat Increase temperature
    Leaf veins turn a lighter color than surrounding tissue followed by a slow bleaching away of green over the entire leaf to a mottled irregular green and yellow pattern. Eventually the entire leaf turns yellow and drop. Vein chlorosis caused by a nitrogen deficiency, cramped roots, or root rot Use a high nitrogen fertilizer, check rootball


    Harvesting
    The ultimate goal of growing citrus trees is to enjoy the fruits of your labor. Knowing when to harvest can be difficult. Here are some facts to help determine when the best time to pick.
    • Generally speaking, acid citrus fruits take 7 to 9 months to ripen and sweet citrus fruits take about 12 to 18 months to ripen depending upon growing conditions.
    • Know the variety of citrus you are growing and what the size, shape, and color of the fruit should be when ripe.
    • Know the season in which the fruit is harvested. Does the fruit ripen in the fall or winter, or does it ripen in the following spring or summer?
    • Keep fruit on tree as long as possible because once harvested it will not improve in quality.
    • Sampling the fruit to determine sweet ripeness is a foolproof method.


    Nursery Links
    Four Winds Citrus
    http://www.fourwindsgrowers.com
    This citrus nursery offers a wide selection citrus varieties on semi-dwarf rootstock.
    Fast Growing Trees
    https://www.fast-growing-trees.com/Citrus-Trees.htm
    This nursery has an assortment of deciduous and subtropical fruit trees. It offers many citrus varieties.



    Last Updated March 22, 2019
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