Quick answer: Most mushroom grow kits produce 2-3 flushes, with the first flush being the largest. Some growers get a small fourth flush, but yields drop significantly after the third.
What Is a Flush?
A flush is one complete cycle of mushroom growth — from the first tiny pins appearing to a full harvest. After you harvest, the mycelium rests, recharges, and produces another round of mushrooms. Each subsequent flush is typically smaller than the last.
Here's what to expect from a typical kit:
- First flush: Largest harvest, usually 60-70% of total yield. Pins appear 7-14 days after opening.
- Second flush: Moderate harvest, roughly 20-25% of total yield. Appears 10-14 days after first harvest.
- Third flush: Smaller harvest, about 10-15% of total yield. May take 2-3 weeks.
- Fourth flush (sometimes): Very small. The substrate is running out of nutrients at this point.
Total yield from a single kit varies by species, but most of our grow kits produce 300-500g (0.7-1.1 lbs) of fresh mushrooms across all flushes. Planning to dehydrate some of your harvest? Our Wet-to-Dry Weight Calculator tells you how much dried mushroom you'll end up with from your fresh yield.
How to Rehydrate Between Flushes
After each harvest, the substrate block has lost moisture. Rehydrating it is the key to getting strong second and third flushes.
Step-by-step rehydration:
- Harvest all mushrooms from the block, including small pins that didn't develop.
- Remove the block from the bag (or leave it in — both approaches work).
- Submerge in cold water. Place the block in a clean container and weigh it down so it stays fully submerged. Use cold tap water — not warm.
- Soak for 6-12 hours. Overnight is easiest. The mycelium will absorb water and plump back up.
- Drain. Remove the block, let excess water drain off for 15-30 minutes.
- Return to fruiting conditions. Place the block back in its humidity setup, mist regularly, and wait for the next flush.
Some growers add a small pinch of salt to the soaking water to discourage bacterial growth, but plain cold water works fine.
When Is a Kit Spent?
Your kit is done when:
- The block has shrunk significantly and feels light and spongy
- No new pins form after 3-4 weeks despite proper rehydration and conditions
- The block shows signs of contamination — green, black, or orange mould
- The substrate is crumbling apart and won't hold together
A spent kit makes excellent compost or garden mulch. Break it up and add it to your garden beds — the mycelium will continue to break down organic matter in the soil.
Maximizing Your Yield
A few practices help you get the most out of every kit:
- Mist consistently. Humidity is the number one factor. Mist 2-3 times daily, or use a humidity tent.
- Don't rush the harvest. Wait until caps flatten out or just begin to curl upward before picking.
- Rehydrate promptly. Soak the block within a day of harvesting — don't let it dry out.
- Maintain fresh air. Mushrooms need oxygen. If stems are growing long and thin with tiny caps, they need more fresh air exchange.
- Keep the temperature right. Each species has an ideal range. Check our temperature guide for specifics.
Ready to Grow?
Browse our grow kit collection — available in Lion's Mane, Blue Oyster, Pink Oyster, and more. Each kit comes with detailed instructions for your specific species.
For the full growing process, read our complete mushroom growing guide. Species-specific tips are in our Lion's Mane guide and oyster mushroom guide.