Introduction & History

While early-season navels like Skaggs Bonanza race to beat the holiday market, the Atwood Navel quietly occupies the other end of the calendar — extending the California navel season well into February and March when other selections have finished. Identified in the 1980s in California's citrus belt, this late-maturing navel addressed a recurring frustration: consumers who loved navel oranges had to switch to Valencia by mid-winter. Atwood stretched that navel window, offering the familiar seedless, easy-peeling character that navels are loved for, but at a time when store shelves would otherwise be stocked only with juice oranges.

History & Origin

Selected in the mid-1980s in the California citrus belt, Atwood emerged from the ongoing effort to extend the navel orange harvest window at both ends. The variety was identified from a population of navel seedling selections being evaluated for late-season performance. Its ability to hold quality on the tree through February and into March without the granulation, drying, or bitterness that plagued other late-held navels made it commercially viable. The variety entered California's commercial plantings during the 1990s, primarily in the San Joaquin Valley and inland Southern California. It complements the succession planting strategy: early navels (Skaggs Bonanza, Newhall) → mid-season (Washington) → late (Atwood, Lane Late).

Botanical Description

A medium-sized, spreading evergreen tree reaching 5–6 m with a moderately dense, rounded canopy. Leaves are typical of navel oranges — medium to large, broadly elliptic, dark glossy green. Flowers are large, white, and intensely fragrant. Fruit is medium-large (7–9 cm), round with a moderate navel formation at the stylar end. Rind is medium-thick, finely pebbled, and develops full orange colour later than early-season navels. Flesh is orange, fine-textured, seedless, and very juicy for a navel orange. The late maturation means fruit accumulates sugars over a longer period, often resulting in higher Brix than early navels. The tree has a slightly more open growth habit than Washington Navel.

Planting & Cultivation

Plant in full sun with well-drained soil, pH 6.0–7.0. Site selection is important for late navels — avoid frost pockets where January/February cold events can damage the still-maturing crop. Mid-slope positions provide the best cold air drainage. Space trees 5–6 m apart. Plant in spring from certified nursery stock. Ensure the graft union is well above soil level (15 cm minimum). Deep, infrequent watering at establishment promotes deep rooting, which improves the tree's drought tolerance during the extended harvest period. Apply organic mulch and install efficient irrigation. In desert locations, orient rows north-south for even light distribution on both sides of the canopy.

Cultivation

Late maturity demands sustained tree nutrition through winter when other navels have been harvested and their trees are resting. Continue moderate potassium applications through December to support fruit quality during the holding period. Nitrogen management is critical — avoid excess that delays colour and promotes lush growth susceptible to freeze damage. The extended on-tree period means fruit is exposed to more winter pest pressure; maintain vigilant monitoring. Canopy management should balance adequate fruit coverage (preventing sunburn on exposed fruit that hangs through sunny winter days) with sufficient light penetration for colour development. Minimal pruning is preferred.

Climate & Cold Protection

Requires warm, dry summers and mild winters (USDA zones 9b–11) with a climate that allows fruit to remain on the tree safely through February–March. The tree itself has standard sweet orange cold tolerance (-3°C briefly), but the late-hanging fruit is vulnerable to freeze damage during winter cold events that would not concern an already-harvested early navel. This makes Atwood best suited to California's mildest citrus areas — coastal-influenced inland valleys, the foothill citrus belt, and protected desert locations. Not recommended for areas with regular January freezes.

Seasonal Care

Spring: Bloom period; apply nitrogen; begin irrigation; thin heavy clusters. Summer: Fruit expansion; maintain irrigation; apply potassium; protect from sunburn. Autumn: Fruit colouring slowly; continue moderate nutrition; other navels being harvested while Atwood continues developing. Winter: Critical period — fruit still on tree; protect from frost; maintain minimal irrigation; harvest from late January through March. Late winter/early spring: Complete harvest; post-harvest pruning; apply dormant treatments; tree begins flower initiation for next season.

Cold Protection

Critical for Atwood because fruit is on the tree during the coldest months. In California's citrus belt, use overhead sprinkler irrigation during radiation frost events — the most effective protection for large acreage. For individual trees, wrap the canopy with frost blankets and use incandescent string lights for supplemental heat. Maintain a thick mulch layer to moderate soil temperature. In windy conditions, temporary windbreaks reduce heat loss. Container trees offer the significant advantage of mobility — move indoors or under cover when freezing temperatures are forecast. If fruit is frost-damaged, assess for ice crystal formation in the juice vesicles before marketing.

Seasonal Care Calendar

Propagation

Propagated by budding onto certified virus-free rootstock. T-budding or chip-budding onto Carrizo citrange is standard practice in California. Certified budwood is sourced through the CCPP at UC Riverside. The variety is a navel — seedless fruit means no seed propagation is possible. Grafted trees begin bearing at 3–4 years with commercial production from year 5–6. The late-season trait is stable through budded generations. Rootstock selection impacts how long fruit can hang without quality degradation — C-35 citrange promotes compact growth and good late-season fruit retention.

Diseases & Pests

The extended harvest period exposes fruit to late-season pest pressure. Brown rot (Phytophthora citrophthora) is the primary concern — winter rains splash soil-borne spores onto low-hanging fruit; prevent by skirting lower branches and applying copper sprays before winter rains. Septoria spot can develop on fruit held through wet winter weather. Scale insects continue feeding through winter and can mark late-harvest fruit. Navel orangeworm is less of a concern for late navels as moth activity is low in winter. HLB/psyllid management follows standard California protocols. Postharvest stem-end rot can develop in stored fruit — handle carefully and maintain cold chain.

Harvesting & Culinary Uses

Atwood reaches initial maturity in late January to February and can be held through March in favourable conditions. Harvest when rind is fully orange and fruit gives slightly to gentle pressure. Test internal quality: Brix should exceed 10 with a sugar-acid ratio of 9:1 or better. The late development allows extended sugar accumulation, often producing fruit with higher Brix than early-season navels. Do not hold past March in most locations — the navel limonin bitterness potential increases, and spring warmth accelerates quality decline. Pick with clippers and handle carefully. Store at 5°C for up to 4 weeks. Like all navels, juice immediately before consuming.

Culinary Uses

Atwood arrives when the early-season navel excitement has faded, providing fresh, high-quality navel oranges in February and March. The fruit's higher sugar content (from extended maturation) makes it exceptionally sweet for fresh eating. Segments are perfect for winter salads with radicchio, fennel, and walnuts. The juice, while subject to the navel limonin issue, is outstanding when consumed immediately — richer and sweeter than juice from October navels. Use the zest in late-winter baking — orange scones, citrus curd, and marmalade. The thick rind makes excellent candied peel, available at a time when other citrus rind options are limited.

Rootstock Guide

Carrizo citrange is the standard, providing CTV tolerance, nematode resistance, and adequate vigour. C-35 citrange produces a slightly smaller tree with excellent fruit quality retention during the late-season holding period — increasingly preferred for Atwood. Trifoliate orange (Poncirus trifoliata) provides maximum cold tolerance, important since the tree must survive winter with a crop load. Swingle citrumelo for Phytophthora-prone soils. Avoid overly vigorous rootstocks (Volkameriana, Rough Lemon) that produce coarse, thick-skinned fruit unsuitable for the navel market. Flying Dragon for container and small garden use.

Container & Companion Growing

Container Growing

Atwood works well in containers on dwarfing rootstock, with the added advantage that containers can be moved under cover during winter cold events — protecting the still-developing fruit without compromising the tree. Use a 50–60 cm pot with drainage. On Flying Dragon rootstock, expect a manageable 2 m tree producing 8–15 fruit. The late maturity means container trees carry ornamental fruit through the winter, adding visual interest. Maintain moderate nutrition through winter to support fruit quality. Water sparingly in winter but do not let the root ball dry completely.

Companion Planting

Plant wind-tolerant evergreen hedges (pittosporum, Xylosma) on the windward side to protect late-hanging fruit from desiccating winter winds. Low-growing leguminous cover crops between rows provide nitrogen and winter ground cover. In home orchards, combine with early navels (Skaggs Bonanza) and mid-season (Washington) for navel oranges from October through March — a 5-month harvest from three trees. Avoid planting near deciduous fruit trees whose fallen leaves in autumn can harbour fungal inoculum that affects low-hanging late citrus fruit.

Common Mistakes to Avoid

Planting in frost-prone locations where winter cold damages the still-maturing crop. Harvesting too early before the late-season sugar accumulation reaches its potential. Using the same nitrogen schedule as early navels, with late applications that delay maturity further. Neglecting brown rot prevention during winter rains when fruit hangs low and wet. Holding fruit past March hoping for further improvement — quality declines rapidly in spring. Not adjusting rootstock choice to account for the extended crop-carrying period.

Frequently Asked Questions