What is a flush?

Flushes are how a block's harvest arrives, so they set how often you pick and when a block is spent. Button mushroom farms call the cycle a flush or a break: Penn State says mushrooms "are picked over a period of 2 to 4 days in a 7- to 10-day cropping cycle" (Penn State Extension). Each flush usually yields less than the last. GroCycle says each crop gets smaller "as more nutrients and water are extracted from the kit" (GroCycle).

The gap between flushes is usually one to two weeks, and sometimes three. UC Cooperative Extension puts oyster flushes about 10 days apart (UC Cooperative Extension). North Spore expects a kit's pins about two weeks after a harvest, says later flushes may take a bit longer, and keeps spraying the kit in the meantime (North Spore help center). GroCycle's oyster kit starts its second crop in 7–14 days, occasionally up to 21 (GroCycle). Our timeline guide lists the gap by species.

Most blocks give two or three flushes. Counts by species:

Mushroom	Flushes	Source
Blue oyster block	2–3	North Spore booklet
Oyster on straw	The first, then 2–4 more	UF/IFAS
Lion's mane block	2	North Spore booklet
King oyster (king trumpet) block	1–2	North Spore booklet
Shiitake block	2–4; indoors up to 4, depending on the soaking schedule	North Spore booklet; UC Cooperative Extension

UF/IFAS says the count depends on "the fungal strain and the ambient environment".

Rest the block in fruiting conditions and soak it only if it has dried out; shiitake is the exception, soaked after each flush. If no pins show, North Spore soaks a kit for about 20 minutes, or 5–10 for lion's mane (North Spore help center). A block is done when a re-soak brings nothing: GroCycle breaks a kit up if "no further crops emerge after 4 weeks" (GroCycle). Our second-flush guide gives rest and soak times by species, and its sources also stop at green mold (Trichoderma).

In Hypha, a bulk block gets flush reminders after it moves into fruiting, and each harvest's weight stays on the block's record.