Most beginners throw away spent substrate after the first flush — and most of the time, that's a mistake. A fully colonised block still holds nutrients, moisture and viable mycelium long after that first harvest. With the right conditions, a second or even third flush is entirely achievable. When the block is genuinely spent, it makes excellent compost — mycelium-rich substrate breaks down fast and adds real value to soil. I've composted spent blocks alongside standard kitchen waste … read more