Citrus hybrid ‘Excalibur Red Lime’

The Excalibur Red Lime hybrid

Excalibur Red Lime was propagated at Excalibur Rare Fruit Tree Nursery in Florida and entered the University of California, Riverside citrus collection from budwood received in 2005. Nursery owner Richard Wilson described it as an accidental cross between Rangpur lime and kumquat. That reported parentage has not been confirmed genetically, but it clearly separates this plant from Key or Mexican lime, Citrus × aurantiifolia.

The UCR accession is filed under Citrus limonia, the Rangpur-lime group, while retaining the reported kumquat ancestry in its cultivar record. Excalibur Red Lime has no wild population or native range of its own. Its history belongs to modern horticultural selection in Florida, with older cultivated citrus lineages from Asia behind its reported parents.

Growing a container tree or shrub

Light

Place Citrus ‘Excalibur Red Lime’ in the strongest home light available, immediately beside a sunny south- or south-west-facing window. Mature leaves tolerate direct sun after acclimation, but a fast move from indoor shade to hot sun can scorch the canopy.

Watering

Allow the surface of the potting mix to partially dry, then check below the surface and water only when the centre is no longer wet. Apply enough water to re-wet the complete root ball and let the surplus drain away.

Substrate and roots

Citrus ‘Excalibur Red Lime’ needs an airy root structure like other container-grown citrus: abundant fine pores for moisture plus larger pores that refill with air after watering. A citrus or loam-based container mix with fine bark and pumice or perlite is suitable.

Temperature

Stable, frost-free conditions support active growth. Keep the container away from cold glass and draughts, and do not leave the root ball wet in cool conditions.

Humidity and airflow

Average household humidity is acceptable when watering and temperature remain stable. Routine misting does not create the sustained humidity this citrus uses.

Fertilising

Use a complete citrus fertiliser that supplies nitrogen, potassium, magnesium and trace elements such as iron, manganese and zinc. Apply it according to the product label while the plant is actively making shoots, flowers or fruit; use the lower end of the labelled rate for a small plant, a recently repotted root ball or a specimen growing slowly.

Problems and solutions for Citrus hybrid ‘Excalibur Red Lime’

• New leaves are yellow between greener veins: The roots may struggle to take up iron and other trace nutrients when the potting mix is too alkaline, cold or persistently wet. Check root condition and the pH of the mix before adding more fertiliser; the yellow-leaf guide helps separate nutrient patterns from watering damage.
• Leaves blacken or drop after cold exposure: Protect the Citrus ‘Excalibur Red Lime’ from frost, cold glass and strong draughts. Keep damaged growth dry, avoid heavy feeding and postpone pruning until living green tissue and dead twigs can be distinguished reliably.
• Cottony clusters, brown bumps or sticky residue: Mealybugs and scale shelter around leaf joints and young stems. Separate the Citrus ‘Excalibur Red Lime’ from nearby plants, gently remove insects you can see and apply an indoor-plant pest treatment as directed, reaching sheltered areas too. Use the scale guide when attached shells make identification uncertain.
• Fruit develops orange-red colouring: Changing rind colour is part of the hybrid’s maturation. Sunken, soft, cracked or wet areas signal a separate problem and should be inspected promptly.

Keep Citrus hybrid ‘Excalibur Red Lime’ away from pets

• The fruit flesh is edible, while leaves, peel and other plant material can irritate cats and dogs.
• These parts contain essential oils and psoralens that may cause vomiting, stomach pain, unusual tiredness or skin irritation.
• Contact a veterinarian if a pet chews the plant or develops symptoms. Seek medical advice if a person becomes unwell after exposure.

Who first published Citrus, and what does the name mean?

Citrus is the classical Latin name used for citron and related citrus plants.

Carl Linnaeus established the genus Citrus in 1753 in Species Plantarum, page 782.