How to Grow King Trumpet Mushrooms at Home: The Complete Guide
TL;DR
King trumpet mushrooms are the meaty “scallops of the forest” that fruit happily on a 5-lb block of supplemented hardwood sawdust. A beginner using a ready-to-fruit kit can expect 1–2 flushes totaling 1–1.5 lb in 5–7 weeks. Spawn+substrate growers can push 2–3 lb from the same weight with better flavor density.
Quick-Facts Box
| Factor | Value |
|—|—|
| Difficulty | Easy–Moderate |
| Time to first harvest | 21–28 days after spawning (kit) or 35–45 days from inoculation (spawn run) |
| Best beginner path | 5-lb supplemented sawdust kit, high-humidity tent |
| Yield expectation | 0.7–1 lb per 5 lb substrate (first flush); up to 1.5–2 lb total across 2–3 flushes |
| Optimal fruiting temp | 55–68 °F (13–20 °C) |
| RH for pinning | 90–95 % |
| Fresh-air exchange | 4–6 full air exchanges per hour (CO₂ < 1,000 ppm) |
Why Grow King Trumpet?
Flavor & Texture
King trumpets (Pleurotus eryngii) have a uniquely dense, almost seafood-like bite. Sliced and pan-seared, they mimic scallops; shredded, they pull like crab. Their umami is deeper than oyster mushrooms and lacks the metallic edge that some shiitakes carry.
Nutrition (research-backed)
A 100 g serving provides ~3 g protein, 2 g fiber, and significant potassium, niacin, and ergothioneine—an antioxidant studied for cellular protection. Studies from Japan and Korea also suggest potential cholesterol-modulating effects, but these are preliminary and not FDA-evaluated.
Cost vs. Buying
Retail prices run $12–18/lb in North America and €20–25/kg in Europe. A $25 five-pound kit reliably yields $15–25 worth of mushrooms and can be composted into garden beds for bonus outdoor flushes.
The 3 Ways to Grow It
| Method | Effort | Up-front Cost | Typical Yield | Failure Rate | Notes |
|---|---|---|---|---|---|
| Ready-to-fruit kit | Minimal | $22–30 | 1–1.5 lb | <5 % | Cut an “X,” mist, wait. |
| Spawn + pasteurized substrate | Moderate | $40–60 (tools amortized) | 1.5–2 lb | 10–15 % | Requires pressure cooker for spawn jars but not for substrate. |
| From-scratch agar → grain → bulk | High | $100+ | 2–3 lb+ | 20–30 % | Full sterile technique; best for scaling. |
What You’ll Need
Below are two lists: (A) the absolute minimum for a kit grow, and (B) the full spread for the spawn+substrate route. Prices are 2024 US averages; swap suppliers as needed.
A. Kit-Only Shopping List (~$30)
1. Ready-to-fruit king trumpet kit (5 lb block, supplemented hardwood sawdust)
2. Spray bottle (1 L)
3. Humidity tent or 20-gal perforated grow bag
4. Small oscillating fan (optional, <$15)
B. Spawn + Substrate Shopping List (first-time setup)
| Item | Quantity | Purpose | Budget Note |
|---|---|---|---|
| King trumpet grain spawn (rye or milo) | 2.5–3 lb | Inoculation | $12–15 from reputable labs |
| Hardwood fuel pellets (oak/alder) | 10 lb | Base substrate | $6 at hardware store |
| Soy hull pellets | 4 lb | Nitrogen supplement | $8 feed store |
| Gypsum (CaSO₄) | 1 lb | Buffer & Ca source | $3 |
| 5-micron filter-patch grow bags (8″×5″×19″) | 5 | Spawn run & fruiting | $0.75 each |
| 70 % isopropyl alcohol | 1 qt | Surface sterilization | $3 |
| Nitrile gloves & face mask | 1 box | Aseptic work | $7 |
| Large tote (66 qt) | 1 | Pasteurization vessel | $12 |
| Sous-vide stick or aquarium heater | 1 | Hold 140–160 °F pasteurization bath | $30 |
| Infrared thermometer | 1 | Spot-check temps | $15 |
| Pressure cooker (≥15 psi, 16 qt) | 1 | Sterilize spawn jars | $70–100 (buy once) |
| Mason jars + modified lids | 6 | Spawn expansion | Reuse kitchen stock |
Total first-time spend: ~$140, but ~$60 after reusable tools.
Choosing & Sourcing Spawn/Kits
- Reputable labs: North Spore (US), Mycelia (EU), Southwest Mushrooms (US), or local university extensions.
- Viability test: If grain spawn smells sour, yeasty, or shows green/black spots, toss it. Healthy spawn smells fresh, earthy, and faintly sweet.
- Kit red flags:
• Block feels loose or crumbly (dried out).
• Visible contamination through the filter patch.
• Production date >3 months old (viability drops). - Strain notes: “King trumpet” is Pleurotus eryngii var. ferulae; avoid P. eryngii var. eryngii (smaller caps). Cultivar “NE-2” fruits best at 55–65 °F; “KTP” tolerates up to 75 °F.
Step-by-Step: The Beginner Method (Grow Kit)
Timeline: 5–7 weeks total.
-
Unbox & inspect
• Check block weight (should be 5 lb ±0.3).
• Look for white, dense mycelium; reject if >10 % green/yellow. -
Choose a location
• Basement, spare bathroom, or wine fridge set to 60 °F.
• Avoid direct sun; ambient 50–500 lux LED or daylight is fine. -
Initiate fruiting
• Wipe a sharp knife with 70 % alcohol.
• Cut a 3-inch “X” on the broad side of the bag, through the plastic but not into the block.
• Fold the top of the bag down, clip to keep CO₂ low. -
Humidity setup
• Slide the block into the humidity tent or perforated grow bag.
• Mist the tent walls 2–3× daily with filtered water to maintain 90–95 % RH.
• Place a small fan 6 ft away on low for 15 min every 2 hrs (smart plug helps). -
Pinning (7–14 days after cutting)
• First pins look like white “popcorn” at the cut edges.
• Reduce misting to avoid direct spray on pins; maintain RH 85–90 %. -
Fruit development
• Over 5–7 days, stems elongate and caps stay small—this is normal.
• Ideal cluster: 3–6 mushrooms, 4–6 in tall.
• If caps flatten and curl upward, raise humidity; if stems elongate and pale, increase fresh air. -
Harvest
• Twist entire cluster at the base when largest stem hits 4.5–5 in (11–13 cm).
• Trim substrate fuzz with a knife.
• Expected wet weight: 10–14 oz (280–400 g). -
Rest & second flush
• Soak block 4 hrs in cold water, drain, return to tent.
• Second flush emerges in 10–14 days; yield ~60 % of first.
• Most kits give 2 flushes; compost block when yield <5 oz.
Step-by-Step: Spawn + Substrate Method
Yield goal: 1.5–2 lb from a 5-lb supplemented sawdust block.
Phase 1 – Substrate Formula & Pasteurization
Master Mix (per 5 lb finished block)
• 2 lb hardwood pellets (≈1.8 L volume hydrated)
• 0.8 lb soy hull pellets
• 1.2 L water (gives 60 % moisture)
• 1 % gypsum (18 g)
-
Hydrate
• Dump pellets into a 66-qt tote.
• Pour 1.2 L 160 °F water, mix with gloved hands until uniform.
• Let cool to room temp; squeeze test: a handful should drip 2–3 drops. -
Pasteurize
• Transfer hydrated mix to mesh laundry bag or pillowcase.
• Submerge in 150 °F water bath (sous-vide set to 150 °F).
• Hold 1 hr; stir once at 30 min.
• Drain 30 min; cool to <80 °F.
Phase 2 – Spawning & Colonization
-
Sanitize workspace
• Wipe tote, scissors, and gloves with 70 % alcohol.
• Work in still air or in front of a DIY glove box. -
Mix
• Add 2.5 lb cooled substrate to 5-micron filter-patch bag.
• Add 0.5 lb king trumpet grain spawn (10 % wet weight ratio).
• Shake vigorously to coat grains; pack loosely—do not compress. -
Seal & label
• Fold top, clip with impulse sealer or zip tie.
• Mark strain, date, and spawn rate. -
Incubate
• Place bags in a dark cabinet at 70–75 °F (21–24 °C).
• CO₂ tolerance is high; no fresh-air holes needed yet.
• Check after 7 days: mycelium should appear as white veins.
• Full colonization: 14–21 days (block turns solid white, no visible substrate).
Phase 3 – Fruiting Trigger
-
Cold shock (optional but increases pin set)
• Move block to 50–55 °F for 12 hrs (basement floor or fridge). -
Cut & introduce fresh air
• Slice a 4-inch “X” on the broad side.
• Move to fruiting chamber:
• Temperature: 55–68 °F (13–20 °C).
• Humidity: 90–95 % RH for pinning (first 3–4 days).
• Lighting: 12 hr on/off cycle, 500–1,000 lux (LED shop light 12 in away).
• Fresh-air exchange: 4–6 ACH (small inline fan on timer). -
Pinning & fruiting
• Pins form 5–7 days post-cut.
• Drop RH slightly to 85–90 % once caps distinguishable.
• Harvest when largest stem is 4–6 in (10–15 cm), caps still slightly curled under. -
Post-harvest
• Twist cluster; trim substrate fuzz.
• Rest block 4–6 hrs submerged in cold water.
• Second flush in 10–14 days; third flush smaller.
• Compost block after third flush or when contamination appears.
End of Part 1. Part 2 will cover growing conditions, timeline, troubleshooting, and FAQs.
Growing conditions that matter — dialing-in King Trumpet
King Trumpet (Pleurotus eryngii) is forgiving, but the margin between “okay” and “spectacular” is razor-thin. Keep the four environmental levers within the ranges below and you’ll get dense, meaty stems instead of skinny oyster-look-alikes.
| Factor | Pinning phase (first 3–4 days after cut) | Fruiting phase (after pins set) |
|---|---|---|
| Temperature | 55–65 °F (13–18 °C) – the sweet spot is 60 °F (16 °C) | 60–68 °F (16–20 °C); avoid >72 °F (22 °C) or stems turn hollow |
| Relative humidity (RH) | 90–95 % RH | 85–90 % RH; below 80 % caps crack, above 95 % bacterial blotch |
| Fresh-air exchange (FAE) | 4–6 air changes per hour (ACH) | 6–8 ACH – King Trumpet is CO₂-tolerant but stems elongate and thin above 1,200 ppm |
| Light | 500–1,000 lux, 12 h on / 12 h off – think bright shade, not direct sun | Same; too much light (>1,500 lux) causes caps to brown and curl up |
| Substrate moisture | 65 % water content (squeeze test: a few drops) | Keep surface beads, not puddles; mist 2–3× daily if chamber RH <90 % |
Pro tip: A small USB computer fan on an interval timer (2 min on / 15 min off) is the cheapest way to hit FAE targets without drying the block.
Timeline — week-by-week expectations
| Week | What you’ll see | What you should do |
|---|---|---|
| 0 | Inoculation day | Label bag with date & strain. Incubate at 70–75 °F (21–24 °C). |
| 1 | White flecks appear | Resist peeking daily. Check once, then leave alone. |
| 2–3 | Block turns solid white | If >80 % colonized, give another 2 days to strengthen. |
| 3.5 | Cold-shock (optional) | 12 h at 50–55 °F. Skip if your ambient is already <65 °F. |
| 4 | Fruiting trigger | Cut “X”, move to fruiting chamber, set timers & hygrometer. |
| 4.5–5 | Pins the size of pencil erasers | Mist lightly, maintain 90 % RH. Do NOT direct fan at block. |
| 5.5–6 | Stems 2 in (5 cm), caps forming | Drop RH to 85 %, increase FAE to 6 ACH. |
| 6–7 | Harvest first flush | Twist cluster at base, trim fuzz, weigh yield. |
| 7.5 | Rest & rehydrate | Submerge block 4–6 h in cold tap water, drain 30 min. |
| 8–9 | Second flush pins | Conditions identical to first. Yield ≈70 % of flush #1. |
| 10–11 | Harvest flush #2 | Repeat rest cycle. |
| 12–13 | Third flush (optional) | Yield ≈50 % of flush #1. Discard block if contamination or smell. |
Total calendar time: 12–13 weeks from inoculation to composting.
Harvesting, storing & cooking
When to pick
- Size: Largest stem 4–6 in (10–15 cm) long and 1–1.5 in (2.5–3.8 cm) thick.
- Cap shape: Margin still curled under; if it flattens or upturns, spores drop and texture toughens.
- Color: Uniform ivory; browning at edges signals over-maturity.
How to harvest
- Support cluster with one hand, twist entire base 90 ° counter-clockwise.
- Trim off substrate crumbs and fuzzy mycelium with a sharp knife.
- Weigh flush immediately; log weight to track performance.
Storage
- Short-term: Paper bag in main fridge compartment, 2–4 °C (36–39 °F), 7–10 days.
- Long-term: Slice stems into ¼ in (6 mm) rounds, sauté in butter 3 min, cool, freeze flat in zip-bags—keeps 6 months.
- Dehydration: Not ideal; rehydrated texture becomes rubbery.
Quick cooking tips
- Scallop hack: Slice stem into ½ in disks, score cross-hatch, sear in cast-iron with butter & soy — mimics sea scallops.
- Umami butter: Blend sautéed trumpets with softened butter, miso, and garlic; roll in parchment for instant steak topper.
- Grill planks: Keep cluster whole, brush with olive oil, grill 3 min per side over medium heat for smoky “mushroom steaks”.
Troubleshooting table
| Problem | Likely cause | Fix |
|---|---|---|
| No pins after 10 days | Too warm (>70 °F), too little fresh air, or RH <85 % | Drop temp to 60 °F, increase FAE, mist 3× daily |
| Aborts (pins blacken & stop) | CO₂ >1,500 ppm or sudden RH drop | Ventilate more, check hygrometer calibration |
| Long, skinny stems | High CO₂ or low light | Move fan closer, raise light to 1,000 lux |
| Cracked caps | RH <75 % | Mist more often, add humidifier on hygrostat |
| Yellow-brown bacterial blotches | Standing water on caps, RH >95 % | Reduce misting, increase FAE, dab blotches with sterile paper towel |
| Green mold (Trichoderma) on block | Contaminated spawn or substrate >30 days old | Isolate bag, harvest any clean mushrooms early, then discard block outdoors |
| Foul, sour smell | Anaerobic bacteria in substrate | Do not open indoors; double-bag and trash |
| Mites or fungus gnats | Substrate too wet, fruiting chamber not cleaned | Remove affected block, wipe chamber with 70 % iso, add sticky traps |
| Second flush pins but stalls | Block dried out after first flush | Submerge 6 h, weigh down with plate, drain thoroughly |
Food safety & first-try cautions
- Cook thoroughly: Heat to ≥165 °F (74 °C) for 3 min. Raw King Trumpet can cause GI upset in sensitive individuals.
- Positive ID: King Trumpet has a lateral or absent stem attachment and white spore print. If in doubt, post photos to r/MushroomGrowers before eating.
- Allergies: Try a thumbnail-sized cooked piece on day 1; wait 24 h before full serving.
- Cross-contamination: Use separate cutting boards for raw mushrooms and other foods; wash hands after handling substrate.
FAQ — the questions beginners actually ask
-
Can I grow King Trumpet in a monotub like cubes?
Yes, but yields are lower. Use 4 in substrate depth, flip lid upside-down for passive FAE, and expect 1–1.5 lb from a 32 qt tub. -
Do I need a pressure cooker?
Only if you make your own grain spawn. Pre-sterilized bags or kits skip this step. -
Why are my stems hollow?
Usually >72 °F or CO₂ >1,200 ppm. Drop temp & increase fan speed. -
Can I reuse the substrate for oyster mushrooms?
Technically yes, but nutrient levels are depleted; expect poor yields and higher contamination risk. -
How do I know RH without an expensive sensor?
Use the “mirror test”: exhale on a small mirror; if it fogs heavily and clears in 5–8 s, RH is ~90 %. -
Is cold-shock mandatory?
No, but it improves pin set by 10–20 % in warm climates. Skip if ambient is already <65 °F. -
Can I grow outdoors in summer?
Only in climates where nights stay below 70 °F. Wine caps are a better summer choice. -
What’s the minimum gear to start?
A 5 lb sawdust kit ($25), spray bottle, and a plastic tote with holes drilled for FAE (~$15 total).
Keep going — explore the series
You just mastered King Trumpet. Next up:
- Oyster 101 – fastest gourmet mushroom to fruit
- Lion’s Mane Masterclass – brainy, fluffy, and surprisingly easy
- Shiitake on Logs – outdoor, perennial, zero plastic
- Reishi Blocks – grow your own “varnish shelf” for tea & tinctures
Bookmark ShroomWire.com/gyo for the full, ever-growing list.
Sources & further reading
- Stamets, Paul. Growing Gourmet and Medicinal Mushrooms, 3rd ed. Ten Speed Press, 2005.
- Royse, Daniel J. “A Global Perspective on the High Five: Agaricus, Pleurotus, Lentinula, Auricularia & Flammulina.” World Journal of Microbiology and Biotechnology 30, no. 1 (2014): 1–8.
- Kwon, Hyuk-Ju, et al. “Optimization of Substrate Formulation for King Oyster Mushroom (Pleurotus eryngii) Cultivation.” Journal of Mushrooms 16, no. 2 (2018): 85–91.
- Cornell Small Farms Program. “King Oyster Production on Pasteurized Straw.” Factsheet #102, 2021.
- Reddit r/MushroomGrowers community grow logs (2020–2024).
More in the Grow Series
New to growing? Start with a grow kit. Then explore the rest of the series:
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– ?P=451
– ?P=447
– ?P=444
– All Grow Guides
Educational Disclaimer
This article is for informational and educational purposes only. It is not
medical advice, mental health advice, diagnosis, treatment guidance, or a
recommendation to use any substance, supplement, therapy, or protocol.
We review publicly available research and explain what the evidence may
suggest. Some studies may be early-stage, observational, animal-based,
lab-based, theoretical, or incomplete. Always consult a qualified
professional before making health-related decisions.
Researched and drafted by Spore, ShroomWire’s AI research assistant, and reviewed by the ShroomWire editorial team before publishing.
