Culture
Winter hardy to USDA Zones 9-11 where this small citrus tree will grow well in sandy, neutral, well-drained soils in full sun to light shade. Best performance occurs in full sun. Provide consistent and regular watering. Avoid wet poorly drained soils. Plants will tolerate brief temperatures around 32°F., but generally will not tolerate frost. North of USDA Zone 9, it may be grown in a container as a houseplant. Use an all purpose, loose, well-drained potting mix. Set container outdoors in late spring in full sun in a location protected from wind. Bring container indoors in fall for overwintering in a bright sunny southern window. In winter, mist plants with water almost daily or use a humidifier (plants love humid environments). Indoor plants usually fruit in fall, but may produce sporadically at any time of the year. Hand pollination may be needed for indoor plants due to the lack of insects. New plants may be grown from cuttings.
Noteworthy Characteristics
Citrus is a genus of about 16 species of evergreen trees and shrubs from Southeast Asia and the East Pacific.
The genus name Citrus is from classical Latin.
Ponderosa lemon or giant lemon was discovered in the 1880s as a chance seedling. Parents are unknown (possible lemon-citron cross). This is a small, thorny citrus tree that typically grows to 10-25’ tall outdoors. It produces huge, bumpy, thick-skinned, yellow fruits that have a sour lemon taste. Although not a true lemon, these fruits can easily be used as lemon substitutes for flavorings, juices and desserts. Fruits on outdoor plants may grow as large as grapefruits. Fruits on indoor plants are smaller (often the size of an orange), but, although few in number, are ornamental attention getters. Shiny dark green leaves are evergreen. Waxy, fragrant, white flowers.
Problems
Susceptible to anthracnose, scab, sooty mold, greasy spot, canker and gummosis. Potential insect pests include aphids, thrips, cutworms, leafrollers, mealybugs, scales and whiteflys. Watch for mites.
Uses
Excellent small tree for fruit production. Where winter hardy, it is ornamentally attractive around homes or patios. May be grown as a houseplant.