How to Grow Mushrooms From a Kit? | Simple Steps Inside

Growing mushrooms from a kit requires only a few basic steps: open the kit per its instructions, provide high humidity with frequent misting, give indirect light and fresh air, keep the block in the right temperature range, and harvest before the caps flatten completely.

For the full breakdown, see our best Grow Your Own Mushroom Kit guide.

Those cardboard boxes with a block of colonized sawdust look simple, and they mostly are. But a kit can still fail—not from bad luck, but from missing one of the three things every mushroom needs after the bag opens: moisture, air, and the right temperature. Each species wants something slightly different, so the single best habit you can build is reading the brand-specific instructions that came in the box. Below we walk through the universal rules that apply to almost every kit, then cover the differences between common types.

Your Mushroom Kit’s Core Needs

Every commercial kit relies on the same principle: the substrate inside is fully colonized with mycelium, and your job is to trigger and sustain fruiting. That means a moist environment with fresh air, indirect light, and stable temperatures. The block must never dry out, but standing water or a sealed bag will suffocate the growth. A loose plastic bag over the kit works better than a tight lid because it holds humidity while letting carbon dioxide escape.

Mist the exposed surface and the inside of the cover two to four times a day, or enough to keep everything visibly damp. Use indirect sunlight or a low-output grow light for about twelve hours a day. Direct sun cooks the block. If the surface starts looking dry between mistings, increase the frequency rather than dumping more water at once—the block takes up moisture slowly, and excess water runs off and pools, which can cause rot.

Opening and Harvesting the Kit

The kit’s outer packaging is cut or removed in a specific way depending on the species. Oyster kits usually call for an X-cut or a slit directly over the intended fruiting site. Lion’s mane kits often use two long slashes across the bag face. For any kit, follow the exact cut pattern shown in that brand’s instructions—cutting too many openings or the wrong shape dries the block unevenly. Once the block is exposed, place it in a humidity tent or under a loose bag within minutes; the exposed surface begins drying immediately.

Harvest when the caps look full but haven’t flattened or curled upward. Oysters grow in clusters that are best removed by gripping the whole cluster at the base and twisting gently upward. Individual stems can be cut at the base with a clean knife. RVR Valley notes that you can harvest at any stage by pushing down on the cap while turning and pulling up. Leftover stumps can rot and reduce later flushes, so remove every piece of mushroom from the block after harvest.

Common Mistakes That Kill a Kit

Most first-time failures come from the same four issues. Overwatering—where condensation pools inside the bag or on the block surface—is the most frequent. Mist often but lightly. Underwatering runs a close second: once the bag opens, the block loses moisture fast, so a full day without misting can set the kit back. Sealing the bag too tightly blocks fresh air exchange, which produces long, thin mushrooms or stops growth entirely. Harvesting too late also matters; a mushroom that has dropped its spores or flattened its cap is lower quality and may delay the next flush.

Temperature is the variable that trips people up most. FreshCap says oyster kits do well at 55–75°F. The safe middle is 65–70°F for most common species, but check the kit’s specific range. A block kept too warm for too long can abort the pins.

Getting More Harvests

Most blocks can produce a second or even third flush if rehydrated between harvests. Mushroom Adventures recommends submerging the block in cold water for two to four hours after the first flush is done, then returning it to the humidity setup. FreshCap suggests a brief cold-water soak after a rest period of about two weeks without watering, unless new growth appears sooner. Not every kit tolerates a full soak—some with delicate casing soil wash out, so follow the brand’s advice. A second harvest is usually smaller than the first but still worthwhile.