Long opened olive-brown Moss Island tea leaves and stems resting in Nik's hand against green foliage.

Tea and Terps · Episode 3

Q&A and Bing Dao

Over a giant-leaved Bing Dao pu'er, Nik and Travis take the community's questions: why some acids stay out of a formula, why nitrate is the expensive form of nitrogen, and how your soil and your air move water through a plant.

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  • Nik and Travis
  • Bing Dao pu'er
  • 2:04:40

The cup

Bing Dao, the ice island

Pu'er comes from Yunnan in China's far southwest, and it comes in two kinds. Sheng, or raw, pu'er is made like a green tea and sun dried, then left to age slowly; shu, or ripe, pu'er is piled and fermented for a month or two, which makes it dark and smooth from the start. Nik's cup is sheng: Moss Island 2018, loose maocha from Bing Dao village in Lincang.

Bing Dao means ice island, and it has been one of the most famous and expensive pu'er villages since the mid 2000s. Its trees are a large-leaf variety, and the leaves are so big they barely fit the pot. Nik brewed them with boiling water for more than ten minutes in total, and they were only just beginning to soften.

Tea
Moss Island / Bingdao Maocha / 冰島毛茶
Origin
Bingdao, Mengku, Yunnan, China, 雲南・勐庫・冰島
Style
Loose-leaf sheng pu’er
Vintage
2018
Brewing
Gong-fu style, 10 grams of leaf, 150 mL Dahongpao zhuni Wanzhu teapot, Jianzi flat foot cup
Source
Tea Hong

What Nik noticed

  • Root beer and herbs
  • Camphor, menthol and wintergreen
  • Tropical hardwood and wild forest
  • Peach and apricot in the late steeps

Special notes

Loose maocha, rather than a pressed cake.

Nik's red clay teapot opened on its wet Bing Dao leaf, beside a pitcher of golden tea and a cup, on air in Episode 3
On air in Episode 3, at 13:18
Two kinds of pu'er
Compared Sheng, or raw Shu, or ripe
How it is madeWithered, pan-fired, rolled and sun dried Piled and fermented for weeks, then dried
The cupGold to amber Close to black
When youngBright and often fiercely bitter Smooth, earthy and never bitter
With ageBitterness softens over years Ready to drink sooner
How a Bing Dao session changed
  1. First steepsRoot beer, camphor and wintergreen
  2. Middle steepsHardwood, forest and spice
  3. Late steepsPeach juice and apricot

Nik's notes from the session. The leaves were still plump after six or seven steeps.

Chapter by chapter

Inside the episode

Press any time to play the episode from that moment. While it plays, the chapter you are in lights up.

  1. The cup
  2. Play from 0:27 WelcomeNik and Travis greet the chat and settle into a session of community questions.
  3. Play from 1:10 Giant leaves from Bing DaoWhat the leaves look like, and why the region is so prized.
  4. Play from 4:03 Two kinds of pu'erRaw pu'er ages slowly; ripe pu'er is fermented in piles for weeks.
  5. Play from 10:10 Yunnan and Bing DaoA remote province, and a village that was a local legend until the mid 2000s.
  6. Play from 13:16 Root beer, menthol and camphorThe first aromas of the session.
  7. Play from 15:43 Bitterness that fadesYoung raw pu'er can be fierce, and its bitterness softens with age.
  8. Play from 18:03 Made, then pressedWithered, pan-fired and dried, then sometimes steamed and pressed into cakes.
  9. Play from 20:27 Cake against loose leafA 2014 cake and the 2018 loose maocha, from the same village.
  10. Play from 28:38 Ice islandThe name, the cooling finish, and wild trees that see no sprays.
  11. Play from 34:43 A red clay potWhy Nik brews this tea in iron-rich Dahongpao clay.
  12. Play from 46:37 Altitude and flavorCold nights and big temperature swings concentrate what a leaf makes.
  13. Play from 50:58 What water to brew withNik filters to zero ppm, and admits there is no single right answer.
  14. Play from 54:51 Purple teaPurple-leaf cultivars made into oolong and other teas.
  15. Play from 1:06:18 Why the leaves are so bigA large-leaf variety, selected and planted generations ago.
  16. Play from 1:10:02 Ten steeps to peach juiceThe camphor gives way to peaches and apricots, and the flavor does not run out.
  17. Community questions
  18. Play from 1:17:55 Why not feed malate?Malate is made right beside the plant's photosynthetic machinery, so Nik leaves it to the plant.
  19. Play from 1:25:55 Nitrate or amino acids?Nitrate is not the villain; it is the expensive form of nitrogen.
  20. Play from 1:31:05 Nitrate is not a dirty wordLiving soil makes nitrate; the question is what it costs the plant to use.
  21. Play from 1:37:31 An energy thresholdEnergy spent reducing nitrate is energy not spent elsewhere.
  22. Play from 1:38:18 Too much nitrate in flowerStretch, airy tops and leafy flowers.
  23. Play from 1:39:46 The ratio that mattersAmmoniacal against nitrate nitrogen, not just the total.
  24. Play from 1:46:51 Plants that build campfiresSkunk cabbage heats its flowers enough to melt through snow.
  25. Play from 1:49:15 Not made for usFlavonoids and terpenes serve the plant first, and people second.
  26. Play from 1:54:18 VPD and the soilTravis's question about humidity, and how soil and air share the work of moving water.
  27. Play from 1:58:58 Run a drier VPDIf your mix holds water well, a drier room lets the plant pull water through.
  28. Play from 2:03:41 Wrapping upQuestions for next time, and an invitation to the Discord.

Terroir

Cold nights, concentrated leaves

A listener asked what elevation Bing Dao grows at and what day-night swings do to aroma. Nik's answer: tea from high, cold places has to cope with big swings in temperature and humidity, and it grows slowly. The compounds a leaf makes to cope build up in a smaller, slower-growing leaf, so the flavor ends up more concentrated.

Most plants can only endure the cold, but a few make their own heat. Later in the episode Nik describes skunk cabbage, which burns its stored sugars fast enough to heat its flowers and melt its way up through snow. For the rest, the response to hard conditions shows up in their chemistry, and that is part of what a tea drinker tastes in a mountain tea.

Hear it at 46:37
Generated sunrise over Bingdao-region mountains, with old tea crowns in the foreground and a village above the misty valley.
Generated regional interpretation of Bingdao's mountain setting near Mengku, Lincang. A cultivated old-tree landscape, not a verified estate or individual tree.
Why mountain tea tastes concentrated
  1. High and coldBig swings between warm days and cold nights
  2. Slow growthLeaves expand slowly under the stress
  3. More per leafProtective and aromatic compounds build up
  4. In the cupMore flavor in every leaf

A general pattern in mountain teas; how much it explains in any one garden depends on the cultivar and the year.

Organic acids

Why not feed malate?

One question went straight to the formulas. Rooted Leaf's carry acetates and citrates, and the listener had spotted a pattern: acetate has one acid group, citrate three, so why skip malate, the one with two? Nik's answer is that malate sits right beside the photosynthetic machinery. Plants make it in the chloroplasts and the cell around them, and they use it, together with potassium, to balance charge and keep photosynthesis running smoothly.

Because the plant already runs that balance so precisely, Nik chose not to add malate from outside and risk disturbing it. Acetate and citrate are different: they are carbon skeletons a plant can take in and route into its own metabolism, and citrate can hold metals such as iron and calcium in solution on the way.

Malate is a very specific flavor of organic acids that sit very close to the photosynthetic machinery.

Nik
Hear it at 1:17:55
A dark swirl of liquid spreading through a glass of water in the sun
Three organic acids
Acid Where the plant meets it Nik's choice
MalateMade beside the photosynthetic engine, paired with potassium Left to the plant
CitrateCentral to respiration; holds metals in solution Used
AcetateThe smallest carbon skeleton, straight into metabolism Used

Nitrogen

Nitrate is the expensive option

Some growers treat nitrate as a dirty word. Nik does not. Nitrate is the oxidized, settled form nitrogen falls into over time, living soil makes it, and the common nitrate salts are fairly benign. The catch is what it costs a plant to use it.

Before nitrate can become part of an amino acid it has to take on eight electrons: two to become nitrite, six more to become ammonium, and only then can it be fixed onto a carbon skeleton. Ammonium and amino acids skip most of that cost. Nik's advice is to look past the total nitrogen in a feed to the ratio of ammoniacal to nitrate nitrogen, because the energy a plant spends reducing nitrate is energy it cannot spend elsewhere. Too much nitrate late in flower, he and Travis agree, tends to show up as stretch, airy tops and leafy flowers.

It's an energy threshold for the plants.

Nik
Hear it at 1:31:05
What nitrate goes through
  1. NitrateNitrogen in its oxidized form
  2. NitriteTwo electrons added, in the cell
  3. AmmoniumSix more electrons, in the chloroplast
  4. Amino acidFixed onto a carbon skeleton as glutamine

Eight electrons in all, supplied by the plant's own energy. Ammonium enters at the third step and amino acids at the last.

Why plants make what they make

Plants do not build those molecules for you

It is easy to talk about terpenes, flavonoids and cannabinoids as if plants made them for us. Nik's reminder near the end of the episode is that these compounds are something else first. They protect the plant from light and heat, deter what wants to eat it, attract what it needs, and help it hold its balance through cold nights and dry days.

That matters for a grower, because it means a plant spends its energy on these compounds when its own situation calls for them. Travis puts it plainly: self-preservation is the first law of nature. The flavor in the jar or the cup comes from compounds the plant made in response to the conditions it lived through.

Hear it at 1:49:15
What a plant's compounds do for it first
  1. Screen lightPigments absorb the light the leaf cannot use
  2. DefendBitter and toxic compounds deter insects and grazers
  3. AttractScents and colors bring pollinators and allies
  4. EndureAntioxidants help it through cold, heat and drought

Real structures

The molecules in the questions

Five molecules from the episode, rendered from real PubChem geometry rather than drawn. Pick one to read why it matters, then turn it in three dimensions.

L-Malic acid

The acid plants make right beside their photosynthetic machinery, and a partner of potassium in balancing charge. Nik's point is to leave it to the plant.

Structure data: PubChem open chemistry database

Molecular structure

Drag to rotate. Scroll or use +/- to zoom.

C4H6O5

L-malic acid, malate's parent acid.

Water

Your soil pushes, your dry air pulls

Travis closed with a question from a friend whose room had drifted off the usual VPD targets. Nik's answer looked past the air to the whole soil-plant-air continuum. Water moves through a plant because of a difference in pressure: the soil pushes and the dry air pulls, and both are measured in the same units, kilopascals.

So the target for the air depends on the soil. If your mix holds a lot of water, run a drier VPD so the plant can pull water through more freely; if your room is humid and hard to dry, choose a faster-draining medium such as coco that cycles between wet and dry more quickly. Chasing a VPD chart without looking at the root zone misses half of the system.

What you wanna do at that point is run a drier VPD

Nik
Hear it at 1:54:18
A white root with fine root hairs reaching into sunlit water
One column of water
  1. SoilHolds water at a pressure set by how wet the mix is
  2. Root and stemWater rises through the plant
  3. LeafEvaporates through the stomata
  4. AirDry air pulls; humid air barely does
Matching the air to the root zone
If Then Why
Your mix holds water wellRun a drier VPD The air can pull what the soil pushes
Your room stays humidGrow in a faster-draining medium The root zone cycles wet and dry faster

Moments worth rewinding

Short cuts into the conversation

Moments from the clip archive. Each one plays the full episode from where it starts, and the short plays on its own.

If your soil holds water well, run a drier VPD

Your soil pushes and your dry air pulls; the target for one depends on the other.

  • Two kinds of pu'er

    Raw pu'er is made like a green tea and aged slowly; ripe pu'er is fermented in piles for weeks before it is dried.

    Hear it at 4:03

  • Same village, cake or loose

    A 2014 cake and the 2018 loose maocha come from the same village; pressing changes how the leaf looks and ages.

    Hear it at 20:27

  • Why a red clay pot

    Nik brews Bing Dao in Dahongpao clay, an iron-rich red clay from the Yixing family.

    Hear it at 34:43

  • Why high elevation concentrates flavor

    Cooler gardens and slower growth leave more of the leaf's protective and aromatic compounds in every leaf.

    Hear it at 46:45

  • Why Nik brews with zero ppm water

    He filters his water to zero, then judges for himself how minerals change each tea. There is no single right water.

    Hear it at 50:59

  • Ten steeps to peach juice

    Late in the session the camphor and root beer give way to peaches and apricots, and the leaves stay plump.

    Hear it at 1:10:02

  • What too much nitrate looks like in flower

    Stretch, airy tops and leafy flowers, in Nik and Travis's experience.

    Hear it at 1:38:18

  • The plant that melts its way through snow

    Skunk cabbage burns its stored sugars fast enough to warm its flowers well above the freezing air.

    Hear it at 1:47:22

Keep listening

More from the series

Episode 3 is the community's episode, and Episode 4 follows the B vitamins into the plant's machinery.

All episodesThe channel on YouTube