Should You Dunk a Monotub or Bulk Casing Grow? Here’s What You Need to Know
Thinking about dunking your bulk grow like a PF cake? It can be done—but it’s usually not worth the risk. Here’s why experienced growers rarely recommend it.
What Is Dunking?
Dunking is the practice of soaking a fully colonized mushroom substrate (usually a cake from a PF tek grow) in water after a flush to rehydrate it. This is a well-established technique with BRF jars and works great because the cakes are small, compact, and easy to handle without much risk of damage.
Why Dunking Doesn’t Translate Well to Bulk Grows
Bulk casing grows—where you crumble spawn jars or bags and mix them with a substrate like coco coir, manure, or our premium casing mix—create a much larger and more delicate "cake."
While the idea of dunking this whole mass to squeeze out another flush sounds like a great idea, it comes with several downsides:
- Fragility of the Mycelial Network: A bulk grow’s mycelium structure is more spread out and fragile. Handling or moving the cake can lead to tearing or damage that delays growth by 5–7 days—or worse, halts it completely.
- Contamination Risks: Exposing a large grow to open water dramatically increases the chance of contamination, especially if your dunk container isn’t sterile.
- Minimal Gains: Through multiple trials, we’ve found that dunking a bulk casing only increases yield by about 10–15% on average. For most growers, the reward doesn’t outweigh the risk.
- Built-in Moisture: Our casing mixes are designed to hold enough water for at least three solid flushes without any dunking required.
So… Should You Dunk a Bulk Grow?
We always tell people: It’s possible, but not recommended.
If you’re an experienced grower and understand the risks, there are some methods that can be used to safely rehydrate your substrate—like targeted misting, bottom-watering, or gentle perimeter soaks. (We’ll cover these methods in detail in an upcoming blog post.)
But for 95% of growers, skip the dunk and focus on proper misting, FAE (fresh air exchange), and temperature control. You'll get more consistent, cleaner flushes—and your grow will thank you.
Final Thoughts
Dunking is one of those techniques that works in small-scale setups but doesn’t scale up well. If you're growing with a monotub or bulk casing tray, trust in the moisture retention of your substrate and don’t risk ruining a good thing. Focus on dialing in your environment, and you’ll see multiple flushes without ever needing a soak.
Stay tuned: In a future post, we’ll explore safe hydration techniques for bulk grows that don’t require full dunking.
Happy growing!
—The Midwest Grow Kits Team