Citrus tree care in zones 9-11
The citrus family -- oranges, lemons, limes, grapefruits, tangerines, and related species -- represents the most economically important group of fruit crops in the world and the backbone of warm-climate home orchards. In zones 9-11, citrus grows outdoors year-round with relatively straightforward.
The citrus family — oranges, lemons, limes, grapefruits, tangerines, and related species — represents the most economically important group of fruit crops in the world and the backbone of warm-climate home orchards. In zones 9-11, citrus grows outdoors year-round with relatively straightforward management. The greatest challenge for home growers in these zones is currently citrus greening disease (HLB), which has devastated production in Florida and is spreading through the Gulf Coast.
I don't grow citrus at my zone 7a Long Island site — it would not survive outdoors. This guide is sourced from UF IFAS and UC Cooperative Extension, the two primary citrus Extension resources in North America.
Cold tolerance by species
Per UF IFAS Extension, cold tolerance varies significantly:
| Species | Cold tolerance | Reliable zone |
|---|---|---|
| Calamondin (x Citrofortunella microcarpa) | Most cold-tolerant; to 20°F | 8b-11 |
| Satsuma mandarin (Citrus unshiu) | To 15-20°F | 8b-10 |
| Meyer lemon (C. meyeri) | To 22°F | 9-11 |
| Kumquat (Fortunella spp.) | To 18-22°F | 8b-11 |
| Valencia orange | To 28°F | 9-11 |
| Grapefruit | To 28°F | 9-11 |
| Navel orange | To 28°F | 9-10 |
| Persian lime | To 28-30°F | 10-11 |
| Key lime | Most frost-sensitive; to 32°F | 10-11 |
For zone 9 growers, satsuma mandarin, Meyer lemon, kumquat, and calamondin are the most reliable choices.