Midwest's Select Bulk Substrate Casing Mix - 5 pounds
Midwest's Select Bulk Substrate Casing Mix - 5 pounds is backordered and will ship as soon as it is back in stock.
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Midwest's Select Bulk Substrate Casing Mix - 5 pounds
Description
Description
Midwest’s Select Bulk Substrate Casing Mix – 5 Pounds
Ready-to-Use • Pasteurized • Perfect Field Capacity for Monotubs & Bulk Grows
Midwest’s top-selling bulk substrate every month, trusted by growers who want consistent results without the mess. Our Select Bulk Substrate is a fully hydrated, pasteurized blend formulated to create an ideal fruiting environment for grain-loving varieties—no mixing, guessing, or measuring required.
Designed for monotubs, trays, and bulk containers, this 5 lb bag arrives at proper field capacity and balanced pH so you can go straight from colonized grain spawn to a clean, high-performance bulk grow setup.
Why Growers Choose our Select Bulk Substrate:
- Ready-to-Use Field Capacity – Fully hydrated to the ideal moisture level for bulk fruiting (no extra prep required).
- Premium Formulation – Made with a proven blend of coco coir, vermiculite, hydrated lime, gypsum, pH buffers, mineral water and Azomite.
- Pasteurized for Performance – Pasteurized (not sterilized) to help preserve the natural anti-microbial benefits of coco coir and support contamination resistance.
- Consistent, Repeatable Results – Uniform texture and pH-stabilized balance in every batch for reliable colonization and strong flushes.
- Bulk-Grow Friendly – Ideal for monotubs, grow bins, and trays using rye grain spawn, 5-grain spawn, or grain jars.
How to Use It (Bulk Grow Steps)
Using Select Bulk Substrate is simple: combine fully colonized grain spawn with this ready-to-use substrate, mix evenly, and let the tub colonize before initiating fruiting conditions. This method helps create a dense network of mycelium and supports strong pin sets and multiple flushes.
For best results: ensure your grain spawn is fully colonized before mixing, break it up thoroughly, and distribute evenly throughout the substrate for faster, more uniform bulk colonization.
Spawn-to-Substrate Ratios & Coverage Chart
One 5 lb bag is designed to be an easy “grab-and-go” amount for common tub sizes and grain formats. Use the chart below to choose the right pairing for fast colonization and high yields.
| Grow Setup | Grain Spawn Amount | Select Bulk Substrate |
|---|---|---|
| Small 28Q Monotub | 1–2 lbs grain spawn | 4 lbs substrate (≈ 1 bag covers it with some to spare) |
| Medium 48Q Monotub | 3–4 lbs grain spawn | 7.5 lbs substrate (≈ 1.5 bags) |
| Large 66Q Monotub | 4–5 lbs grain spawn | 10 lbs substrate (≈ 2 bags) |
Quick rule of thumb: many growers prefer a 2:1 or 3:1 substrate-to-grain ratio for strong colonization and consistent flushes (example: 6 lbs substrate + 2–3 lbs grain).
What’s Inside
Select Bulk Substrate is an expertly balanced bulk mix built for consistent performance in monotubs and trays:
- Coco coir + vermiculite for structure, water retention, and consistent hydration
- Hydrated lime + pH buffers to help stabilize conditions
- Gypsum + mineral water to support healthy mycelium development
Storage & Shelf Life
- Short-term: Store sealed at room temperature in a clean, dry place.
- Longer storage: Keep sealed in the refrigerator for up to 6 months. Do not freeze.
- Best practice: Avoid extreme temperature swings that can cause condensation inside the bag.
Included Bonus Guide
Your order includes access to our step-by-step Bulk Growing Guide (PDF) to help you go from colonized grain to a full monotub grow with confidence.
Let customers speak for us
I have always had a great experience with Midwest products. There delivery time is fast and exactly what I ordered. Not once has my substrate been to dry or have I had any contamination. I only have two tubs going right now but definitely will be expanding soon. Thank you for great products at affordable prices.
...and that is viable liquid culture mushroom spores, enough for lots of microscope work, let me tell you.
I pre-stired the jar to show the floating mycellium after nine days. I've been real conservative on the temperature, not letting it get too high, but still I've got great growth.
Once I saw the successful first attempt, I ordered another 10 ounce kit to arrive shortly.
Hey Midwest, thanks for offering the two sizes of the LC kit. I can feel big time, while using the small kit.
Wish you had stickers so I could rep you.
Been doing some agar-related experiments in this guy along with spawn bag inouculation (which I'm not sure is necessary because I've never had a contamination from a Midwest Grow Kits spawn bag - the 5-grain ones are top doggity!)
Just what I needed. I really like the scale and the folding cover.
I’ve been using them for a couple of years and they have always given me great products and customer service is where they really shine though so if you are just starting out or like me an old hand at mushroom cultivation this is the place you need to be pictured is just one of the sizes and the picture is from a second flush also🤪
This worked perfectly as described. Easy to use and the yields were amazing. I make my own now but still get lazy sometimes and order this.
Enjoy
This thing was beautiful to grow. Exactly as described.
Couldn’t be easier or more awesome of an experience. Highly recommend due to its ease and overall experience. Not to mention the benefits from the fruits. I add dehydrated/ground fruits to my morning coffee for immune boost, anti inflammatory and energy boosting properties. You will be glad you got this one. The price is so cheap and the experience is so worth it. Enjoy
I placed my very first grow in a minitub into the automated ecosphere. It kept humidity and light schedule perfect with FAE on a timer 60 seconds on 3x a day. Fruits were huge and plentiful! Im going to fruit my BRF cakes in there next. Midwest is my main supplier of kits and materials. I have the Ultimate Kit with incubator also. Set it up per instructions and it'll serve you well for a long time!
This my second time ordering and both times have been great! No contamination and a fantastic final product. I will definitely order again.
Your products have been consistent and i get the best results with it..
Thank you for this service..
Came in 4 days
Colonized in 14 days now in fruiting chamber .
Looking forward for fresh turkey tail mushrooms.
I recently bought the Midwest Growers small mushroom monotub 2-pack (amazing price for two). They are perfect size for a colonized block! I am currently growing two shiitake blocks and one king trumpet mushroom block and the tubs make it very easy.
My second time growing. First time I bought two different brands of all in one bags from Amazon. Did not work, they both stalled and never fruited. This little kit was my last ditch effort and I’m sitting here less than 8 weeks after ordering and amazing results
I ordered 2 - 10lb blocks and was a little worried that they were plainly wrapped and different sizes. I weighed them and 1 was 8lbs the other 12lbs so the total was correct. Expanded to the expected volume (picture included of smaller block)
These are the best Monotubs on the market for the price they are built well and I wish I had 4 more lol
https://youtube.com/shorts/6uqucyx0RJk?feature=share
