orange tree with fruit and blossoms (17906 bytes)

Citrus Trees: an Ideal Indoor Plant Selection

By Sheri Hunter, Colorado Master GardenerSM, Colorado State University Cooperative Extension, Denver County

A citrus tree may be the ideal houseplant for a warm sunny room. Their shiny, dark green leaves and fragrant blossoms add to the appeal of their brightly colored, ornamental fruit.

Citrus trees need fast draining, fertile soil. They require 5-6 hours of sunlight. Feeding with a high-nitrogen, acid fertilizer should be done in late winter, June and August.  In return for this minimal required care, you will be rewarded with continuous, year-round fragrant blooms and fruit.

When grown outdoors in favorable conditions, trees grow to 20 feet or higher. Indoors, they may be kept at four to five feet.

Pests and Diseases

Citrus, as a rule, are bothered by few pests when grown as a houseplant. Yet where there is a rule, there is an exception.

Protected indoors from normal predators, insect pests can multiply until a plant is overwhelmed. These pests may include aphids, mites, scale, and mealybugs. This is most likely to occur if the plant is weak or malnourished.  Overwatering, poor container soil drainage, increased salinity of container soil, and lack of nutrients (nitrogen,zinc or iron) are conditions that may weaken the plant making it more susceptible to insects and disease.

In addition to correcting any existing environmental problems, the following measures may be needed:

Troubleshooting Indoor Citrus: Pests and Diseases

  • If the season permits, and the container is of a size that makes it feasible, consider moving your plant outside to expose pests to predatory insects.Keep large pots permanently on a frame with wheels so you can roll trees in and out for spraying and other citrus care.
  • Outside with a garden hose, or indoors in a deep sink or shower, rinse the plant with insecticidal soap solution. Allow the soap to dry and wait for several days before using any water rinse. Washing the soap off right away will defeat pest control efforts. Routinely keep plant free of dust and minor aphid pests by rinsing with a stiff stream of water. Repeat treatments may be necessary.
  • Persistent scale infestations frequently respond to light summer oil spray applied in spring and fall. Follow directions on the product label and don't spray indoors unless the product is so labeled and you have adequate ventilation.
  • If you resort to chemical pesticide therapy, be sure to pick a product that is recommended for both the plant and the insect you are treating. Read the label and follow the directions carefully. Always remember to wash your fruit after using chemicals, especially if you intend to use the rind.
  • If the problem is severe, you may want to compost the plant and start over with something new. In this case, be sure to clean your indoor space thoroughly, and consider a period of quarantine.
  • Fungal ailments of citrus manifest in yellowing, dropping foliage. Root rot may be developing related to heavy, waterlogged soil. Reduce your watering frequency. Never allow the plant to stand in water.

Here are a few suggested citrus trees for the new grower:

Citrus Tree Characteristics   Varieties

kumquat 

Very hardy; white flowers have pungent sandalwood-like scent; good marmalade fruit Fortunella margarita

F. japonica

F. crassifolia

lemon 

Less dependent on heat for fruit production; Meyer’s is more disease resistant ‘Meyer Improved’ dwarf

‘Lisbon’

‘Ponderosa’ dwarf

limequat

Hybrid of Mexican lime and kumquat; shrub-like habit; edible rind  ‘Eustis’

‘Tavares’

sour oranges

mandarin needs heat for best flavor Calamondin (mandarin)

‘Rangpur’ lime


Photograph of dwarf orange tree by Judy Sedbrook.

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Date last revised: 01/05/2010