From grain spawn to first harvest
A start-to-finish timeline for inoculating production substrate with Haywood spawn.
The gap between "I inoculated my substrate" and "I'm holding a harvest" feels unpredictable the first time through, but it isn't — there are a small number of checkpoints, and knowing what should be happening at each one tells you whether you're on track or need to intervene.
Inoculation to full colonization
How much grain spawn you use relative to substrate volume is the single biggest lever on colonization speed — a heavier spawn ratio colonizes faster and out-competes contaminants more reliably, which is why we don't recommend stretching a bag of spawn further than it's sized for. Depending on strain, substrate, and temperature, full colonization typically runs two to four weeks. The mycelium should be advancing visibly week over week, not stalling — see our guide on reading colonization for what that progression should actually look like.
The transition most growers rush
"Looks white" and "fully colonized" aren't the same thing, and moving to fruiting conditions too early is one of the most common ways a promising grow underperforms. Shiitake is the clearest case: it needs a full browning period after visual colonization — the surface going leathery and brown — before it's actually ready, and a shiitake block pushed to fruiting conditions while still white usually responds poorly. For every strain, waiting for substrate to be colonized through and through, not just on the surface, is worth the extra few days.
First flush to ongoing harvest
Once fruiting conditions are introduced, expect pins within a few days to just over a week depending on strain, and then roughly another week from visible pin to harvest-ready caps. Harvest just before caps fully flatten for the best texture and shelf life — waiting for "bigger" past that point mostly adds spore drop and softer flesh, not useful yield. After harvesting, rest the substrate a few days before the next flush; expect each successive flush to be smaller than the last, which is normal substrate depletion, not a sign anything went wrong.