Light: Full sun for best fruiting; provide protection from intense western afternoon sun, especially for young trees. Star Ruby is more prone to heat stress and sunburn than some other grapefruit varieties.
Water: Deep, regular irrigation; not drought tolerant. Wet the root zone approximately 18–24 inches deep, then allow the upper few inches of soil to dry before watering again. Increase frequency during Phoenix summers and reduce it in winter; keep emitters away from the trunk and expand coverage as the canopy grows.
Soil: Well-drained sandy loam or loam. Avoid waterlogged soil and planting too deeply; keep the root flare above grade. Phoenix’s alkaline soils may cause micronutrient deficiencies.
Mature size: Typically 10–15 feet tall and wide on semi-dwarfing rootstock; actual size depends on rootstock, growing conditions, and pruning.
Bloom: Primarily late winter through spring, usually February–April in Phoenix.
Evergreen / deciduous: Evergreen.
Growth rate: Moderate; rootstock, irrigation, nutrition, and heat stress influence growth.