Organic Koshun Oolong Tea: Japan's Floral Single-Origin Cultivar Explained

Most oolong tea on supermarket shelves comes from China or Taiwan, with rolled leaves, roasted notes, and a category people know from milk oolong or tie guan yin. Japanese oolong is different: smaller production, often single-cultivar, and processed with the same care Japanese growers apply to sencha and gyokuro.

Our 100g organic Koshun oolong is a single-origin tea from Haruno Village, Shizuoka, built around the Koushun (香駿) cultivar. It brews a deep golden honey cup with floral, apricot, plum, and grape notes, closer to an elegant black tea aroma at first sniff, then opening into something distinctly oolong on the palate.

If you have searched for organic oolong tea, Japanese oolong tea, or loose leaf oolong and found mostly generic blends, this is the cultivar-level story behind ours.

Shop: 100g Koshun oolong · Loose leaf brewing hub · Green tea range · Brewing guides

At a glance

100g Organic OOLONG Tea (Single Origin Koshun Cultivar)

JAS organic Koshun cultivar oolong, 100g loose leaf from Shizuoka.

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What is oolong tea?

Oolong (烏龍, “black dragon”) sits between green tea and black tea on the oxidation scale.

All true tea is Camellia sinensis. Oolong is not a separate plant. It is the same leaf, allowed to oxidise partway before drying. That partial oxidation builds theaflavins and thearubigins (polyphenols associated with oolong’s deeper colour and rounder body) while keeping much of the fresh, floral character green tea drinkers enjoy.

Japanese oolong is still rare in export markets. Volumes are tiny next to Taiwanese high-mountain oolong or Fujian tie guan yin. What you get instead is often one farm, one cultivar, one season, which suits drinkers who already love single-origin sencha or ceremonial matcha.

The Koushun (Koshun) cultivar: 香駿

Koushun (こうしゅん, sometimes written Koshun in romaji) is a Japanese tea cultivar registered in 2000 after breeding work in Shizuoka from the 1970s. It was developed by crossing Kurasawa and Kanayamidori, then selecting the offspring with the most distinctive aroma.

The name is deliberate:

• 香 (kō): aroma, fragrance
• 駿 (shun): from Suruga, the historic province that covers much of present-day Shizuoka

In other words: “the aromatic tea of Shizuoka.” That matches what you taste in the cup.

What makes Koushun different from Yabukita?

Yabukita is Japan’s most planted sencha cultivar: reliable, grassy, familiar. Koushun was bred for something else entirely:

According to cultivar records (My Japanese Green Tea: Koushun) and Japanese tea research summaries:

• Aroma is the headline: floral, herbal, noticeably different from Yabukita even to casual drinkers
• Budding is normal (not ultra-early), with harvest about one day before Yabukita
• Cold tolerance is good: helpful in Shizuoka’s mountain valleys
• Liquor tends toward bright yellow-gold, balanced, with a long aftertaste
• As oolong, those aromatics survive partial oxidation and show up as apricot, plum, honey, and grape rather than heavy roast

Purematcha’s Koshun oolong is 100% this cultivar from an organic farm whose teas have placed in the Japanese Ministry of Agriculture Tea Competition, one of the most respected professional competitions in Japan.

What does Koshun oolong taste like?

Our product description calls it “a tea that will stay imprinted in memory”, and customer reviews echo that: “very mild and delicate”, “brews super quick”, “already look forward to my third brew.”

On the nose: sweet and elegant. Some people say it reads closer to a refined black tea at first, before the oolong fruitiness opens.

In the cup:

• Floral top notes: not perfumed but fresh
• Stone fruit: apricot and plum
• Honey and grape: the “golden honey” liquor is not marketing language; it is what you see in the yunomi
• Light citrus on the finish
• Low astringency: gentle enough for afternoon drinking without milk

Colour: deep golden amber, deepening slightly on second and third steeps.

Compared with Taiwanese oolong: less roast, less rolled-ball drama, more transparency and clarity. Compared with Chinese oolong: less charcoal, more Japanese precision in the leaf.

JAS organic: why clean farming matters for flavour

Our Koshun oolong carries JAS (Japan Agricultural Standards) organic certification, audited through Ecocert. On the farm that means:

• No synthetic pesticides or routine chemical fertilisers
• Organic compost and manual weed control
• Full traceability from field to export

For oolong especially, clean leaf matters. Partial oxidation concentrates whatever is in the leaf: aromatics and any off-notes from heavy conventional farming. Organic Koshun tends to show a brighter, purer floral profile without the flat “bag tea” finish some conventional oolongs pick up.

We wrote a longer guide on what organic certification means for Japanese tea farms in organic Japanese tea farming. The same principles apply here.

Purematcha also independently lab-tests our range in Australia for heavy metals and pesticides. See Sipping safely: heavy metals in teas.

Health benefits often associated with oolong tea

Tea is food, not medicine, but oolong has been studied for decades, and several compounds show up consistently in research summaries. Always read these as general wellness context, not treatment claims.

Polyphenols and antioxidants

Like green and black tea, oolong delivers polyphenols, plant compounds that help neutralise free radicals linked to oxidative stress. Oolong’s partial oxidation creates a mix of catechins (more common in green tea) and theaflavins / thearubigins (more common in black tea). That dual profile is one reason oolong is often described as offering “the best of both worlds.”

L-theanine and calm focus

Japanese teas, including oolong processed from cultivars like Koushun, contain L-theanine, an amino acid linked in research to calm alertness and moderated caffeine release. A cup in the afternoon can feel focused but not jittery, especially compared with coffee.

Metabolism and weight management (popular interest)

Oolong appears frequently in searches around metabolism and weight management. Some human studies have looked at oolong polyphenols and fat oxidation or energy expenditure after meals. Results vary by study design; the honest takeaway is that oolong may support a healthy lifestyle alongside diet and movement, not replace them.

Heart health and blood sugar (emerging research)

Population studies and small trials have explored links between regular tea drinking (including oolong) and markers like blood lipids or post-meal glucose. Evidence is promising but not definitive for any single cultivar. If you have a medical condition, speak with your health professional. Tea complements life; it does not prescribe it.

Caffeine: moderate and resteep-friendly

Koshun oolong is moderately caffeinated, typically well below a double espresso, and gentler than many Assam black teas because you use short steeps and can dilute across three or four infusions. Sensitive drinkers often find the second steep the sweetest spot.

How to brew Koshun oolong (video + steps)

This is the same method shown on our product page and in Stephen’s YouTube brewing guide:

How to brew organic Koshun oolong: 5 g leaf, 90°C water, one-minute steep, multiple infusions.

Quick reference

Teaware: a Tokoname kyusu or HARIO glass teapot with infuser works well. Store opened leaf in an airtight canister away from heat and light.

For temperatures across our full range, see brewing temperature chart and how to brew Japanese loose leaf green tea.

Who is this tea for?

Koshun oolong suits you if:

• You want organic Japanese loose leaf beyond sencha and matcha
• You enjoy floral, honeyed cups without milk
• You are curious about single-cultivar tea: the same way wine lovers chase grape varieties
• You searched buy oolong tea online or best organic oolong tea and want provenance, not a generic blend

It may not suit you if you only drink heavy roasted oolong or strong Assam-style black tea. Koshun is delicate by design.

Explore more Japanese loose leaf

Related teas: Organic sencha gold · Gyokuro blend · Benifuuki wakoucha (Japanese black tea) · Yamabuki Nadeshiko fermented tea

Guides: Loose leaf brewing hub · Green tea glossary · Organic Japanese tea farming

Shop the range: All loose leaf green tea