Pronounciation: CI-trus ja-PON-i-ka

Hardiness zones
Sunset 12-24
USDA 9-11

Landscape Use: Nice small patio tree, edible fruit gardens, container tree, raised planters, great for small residential landscapes, oasis and mesic landscpae designs, not for xeric or dry desert landscape design types.

Form & Character: Upright and rounded, diminuative, non-offensive, formal, tropical, clean.

Growth Habit: Evergreen, woody, broadleaf perennial small tree, moderately grows from 6- to 25-feet tall with equalk spread, dense upper canopy.

Foliage/Texture: Oval to lanceolate, simple medium-green leaves to 2-incles long, without winged petioles; medium texture.

Flowers & Fruits: Small, axillary, star-shaped, white flowers, 5 petals, magenta pink sepals, fragrant; fruits are small to 1-inch long hesperidium, orange when ripe, and range in shape from rounded to oval.

A culinary mindbender: The ripened fruit endocarp juice vesicles of kumquat are very bitter, but the rind (exocarp + mesocarp) is surprisingly sweet.

Seasonal Color: Orange fruits in late fall through early spring sometimes overlapping with white flowers produced in early spring (later February in Phoenix).

Temperature: Heat tolerant to 115^oF, cold hardy to 25^oF.

Light: Full sun, but avoid reflected western sun on exposed trunk. Like other citrus, trunks of kumquat are often painted white to prevent sunscald injury, especially if trunks are exposed to direct sunlight by the ill-advised raising of the canopy base by pruning.

Soil: Like all Citrus, kumquats have a relatively high nutritional requirement. When grown in alkaline desert soils (essentially all of Phoenix), regular soil-based applications of a balanced, complete fertilzer with micronutrients are essential for maintaining plant health and vigor. Fertilzer applications should occur three times per year in January, May and September.

Watering: Regular water to maintain a densely-foliated canopy during the warm season. Taper off water applications during fall and ramp up water applications during spring. During winter, supplemental water in some years (with adaequate winter rainfall) will not be needed.

Pruning: A conservative approach to pruning kumquat is strongly advised. If needed, only lightly head back. Avoid excessive crown raising!

Sage pruning advise: If in doubt about whether or not to prune, then its ALWAYS best to leave kumquat trees alone.

Propagation: Mostly grafted onto rootstocks of rough lemon and trifoliate orange.

Disease and Pests: Aphids and thrips, sometimes scale, phytophthora root rot.

Additional comments: Kumquat is a good mesic small landscape tree for smaller spaces. Fruit rind used for jellies, etc. Nice container plant when grafted onto dwarfing rootstock. Special care is needed to maintain proper nutritional status of kumquat. Fertilizer in January, May, and September with 0.7 pounds of nitrogen per tree. Kumquats might need Epsom (magnesium sulfate) salts once per year and chelated micronutrient fertilizers (liquid formulation best for landscape trees) twice per year.

The Fukushu or Changshou kumquat is a dwarf, compact, thornless tree from Japan with larger leaves and fruits that are about 1.5-inches long, oval, and depressed at the apex. The fruit rind is thin and orange when ripe. Its authority is disputed.

Special Note: X Citrofortunella sp. (limequat) is a bigeneric hybrid that includes three named varieties, Eustis, Lakeland, and Tavares, which are each hybrid selections between West Indian lime (Citrus aurantifolia) and kumquat. They were made by W. T. Swingle of the United States Department of Agriculture in Florida in the early 20th century and were named and originally described in 1913.

Resource: The Citrus Industry Vol. 1 (1967)