How to Grow King Trumpet Mushrooms with a Grow Kit

Grow thick, meaty, restaurant-quality King Trumpet mushrooms at home with this ready-to-fruit grow kit from Redwood Mushroom Supply. Each block arrives fully colonized on a hardwood-based substrate and professionally incubated, so you can focus on fruiting — no prep work or special tools required.

King Trumpets are prized for their dense stems, rich umami flavor, and excellent texture for searing and grilling. With steady humidity, fresh air, and patience, you can expect impressive harvests in just a few weeks.

How to get started

Preparation and Opening the Bag

Optional Cold Shock (Recommended): To trigger stronger, more uniform pinning (especially if your growing area is warm), place the unopened bag in a refrigerator at 34–40°F for 12–24 hours. Then return it to your fruiting area.
Loosen the Surface: Gently massage the top of the block through the plastic to loosen the mycelium and encourage even pin formation.
Monitor for small pins pressing against the plastic at the top of the bag.
Once pins appear, cut a 2–3 inch opening.

Fruiting & Daily Care (Days 10–14 After Pins)

Fill the included sprayer with filtered or distilled water and lightly mist the exposed surface 2-3 times daily, or more often in dry conditions. Use a fine mist (damp, not soaked). Increase frequency if your space is dry.
Keep up this routine, and small white bumps or knobs (pins) typically appear within 1–2 weeks after starting fruiting conditions.

Watch Your Mushrooms Grow

Watch your mushrooms grow! Be sure to mist your mushrooms every day to keep them moist. As mushrooms grow, gradually roll the bag down, leaving about 5 inches of plastic above the substrate to maintain a helpful microclimate.
As your mushrooms grow, keep an eye out for signs that they’re ready to be harvested. Refer to our harvesting guide below for more information!