Introduction & History

Okitsu Wase is the earliest-ripening Satsuma mandarin clone — a variety that pushes the Satsuma season forward by 2–3 weeks, providing fresh seedless mandarins as early as late September when no other citrus is ready. Developed at Japan's Okitsu Branch of the Fruit Tree Research Station (now NARO) in Shizuoka Prefecture around 1940, Okitsu Wase was selected as a particularly early-maturing mutation of the Miyagawa Wase Satsuma. In Japan's competitive mikan market, where being first to market commands significant price premiums, Okitsu Wase became an important commercial variety in regions where early-season production is viable. The variety shares the Satsuma group's legendary cold hardiness — surviving -9°C on Poncirus trifoliata rootstock — while maturing weeks before standard Owari. For cold-climate citrus growers who need every day of growing season to ripen fruit before frost, Okitsu Wase's precocious maturity can be the difference between a full harvest and a lost crop.

History & Origin

Okitsu Wase was identified as an early-maturing selection at Japan's Okitsu Branch of the National Fruit Tree Research Station in Shizuoka Prefecture, central Japan. The station, established in 1902, has been Japan's primary center for Satsuma research. Okitsu Wase was selected from Miyagawa Wase (itself an early-maturing Satsuma clone) around 1940, gaining recognition for its exceptionally early ripening. In Japan's stratified mikan market — where early, mid, and late clones fill different harvest windows — Okitsu Wase occupies the extreme early position, with fruit available from late September. The clone has been adopted in other Satsuma-growing regions including Spain, Turkey, and the US Gulf Coast.

Botanical Description

A compact, spreading tree reaching 2.5–3 m — slightly smaller and less vigorous than Owari Satsuma. The dwarf habit is an advantage for container culture and small gardens. Thornless, with large, dark green leaves typical of Satsuma. Fruit is medium-sized (55–70 mm), oblate, with the characteristic loose, puffy, easy-peel rind of all Satsumas. Rind color develops very early — deep orange by late September in warm areas. Flesh is bright orange, tender, seedless, and juicy, with Brix of 9–10° and very low acidity. The flavor is mild and sweet — identical to other Satsuma clones when fully mature, though early-harvested Okitsu Wase may lack the complexity of later-ripening clones.

Planting & Cultivation

Plant in full sun in well-drained acidic to neutral soil (pH 5.5–6.5), spacing 2.5–3.5 m — Okitsu Wase is very compact. The early maturity makes it the ideal choice for the coldest viable citrus-growing locations (zone 8b), where every extra week of maturity before frost is critical. Choose the warmest microclimate available — south-facing walls, raised beds, protected courtyards. Graft onto Poncirus trifoliata for maximum cold hardiness. Container culture on Flying Dragon is superb.

Cultivation

Culture is identical to other Satsumas — low nitrogen (50–80 g per year of tree age), moderate irrigation, minimal pruning. Okitsu Wase's very low vigor means it needs even less fertilizer than standard Owari. The compact size makes management easy. The early maturity means harvest can begin by late September — 2–3 weeks before Owari — providing fresh mandarins at the very start of the citrus season.

Climate & Cold Protection

USDA zones 8b–11, cold-hardy to -9°C on Poncirus trifoliata — identical to Owari and other Satsuma clones. The early maturity is Okitsu Wase's critical advantage in cold climates: fruit matures 2–3 weeks earlier than Owari, significantly reducing the risk of losing the crop to early frost in zone 8b locations.

Seasonal Care

Spring (Mar–May): Moderate bloom. Very light fertilizer. Monitor for aphids. Summer (Jun–Aug): Fruit enlargement. Moderate irrigation. Light second fertilizer. The compact tree is easy to manage. Autumn (Sep–Nov): Very early harvest — Okitsu Wase is ready from late September. In cold zones, harvest before first frost. Rind colors very early. Winter (Dec–Feb): Tree is dormant and cold-hardy. Protect young trees from extreme cold. No fruit on tree at this time.

Cold Protection

Same as Owari — tree hardy to -9°C on trifoliata, fruit dies at -2°C. The earlier harvest timeline reduces frost risk significantly — fruit is off the tree 2–3 weeks before Owari, providing a wider safety margin in zone 8b locations.

Seasonal Care Calendar

Propagation

Always bud onto Poncirus trifoliata for cold-climate plantings. Flying Dragon (P. trifoliata dwarf) is ideal for containers — the already compact Okitsu Wase on Flying Dragon produces a miniature 1–1.2 m tree. Okitsu Wase budwood is available from Japanese citrus programs and from CCPP at UC Riverside. The variety is not patent-protected.

Diseases & Pests

Same as Owari Satsuma — low pest pressure in cold-climate plantings. Phytophthora managed by trifoliata rootstock. The very early harvest reduces cumulative pest exposure compared to later-maturing varieties.

Harvesting & Culinary Uses

Okitsu Wase matures late September through November — 2–3 weeks before Owari. Same rules as all Satsuma: do NOT harvest by rind color (colors early before full sweetness); test Brix (target 9°+). In cold-climate zones, the earlier maturity provides a crucial window to harvest before the first killing frost (-2°C for fruit).

Culinary Uses

Identical to Owari Satsuma — fresh eating, juice, chinpi (dried peel). The early-season availability is the key culinary distinction — Okitsu Wase provides the first fresh mandarins of the season when no other seedless citrus is available.

Rootstock Guide

Poncirus trifoliata: Essential for cold-climate culture. Flying Dragon: Ideal for containers — ultimate cold-hardy dwarf. Carrizo citrange: Only for mild climates (zone 9b+). Same rootstock requirements as all Satsuma clones.

Container & Companion Growing

Container Growing

Okitsu Wase on Flying Dragon is perhaps the most compact, productive container Satsuma available — a 1–1.2 m tree in a 30–50 liter pot producing 15–30 seedless mandarins by late September. The very early maturity means harvest before most other citrus has colored. Ideal for zone 7b–8a container culture where the extended growing season before winter is limited.

Companion Planting

Plant alongside Owari (mid-season) and other late Satsuma clones for extended harvest. In cold-climate gardens, pair with kumquat and yuzu for a diverse cold-hardy citrus collection.

Common Mistakes to Avoid

1. Harvesting too early — even though Okitsu Wase colors earlier than Owari, internal maturity still lags rind color by 2 weeks. 2. Over-fertilizing — even less nitrogen needed than Owari due to lower vigor. 3. Not choosing Okitsu Wase for the coldest locations — its early maturity is a decisive advantage in zone 8b. 4. Using non-cold-hardy rootstock in cold areas. 5. Expecting larger fruit than Owari — Okitsu Wase fruit is slightly smaller.

Frequently Asked Questions