Midwest's Select Bulk Substrate Casing Mix - 7.5 pounds
Midwest's Select Bulk Substrate Casing Mix - 7.5 pounds is backordered and will ship as soon as it is back in stock.
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Description
Description
Midwest's Select Bulk Substrate in a 7.5 lb bag is a pasteurized, pre-hydrated CVG mushroom substrate (coco coir, vermiculite and gypsum with lime and trace minerals), sized to fill a Medium 44Q monotub with one spawn bag.
Same blend as our 5 lb bags, in the exact amount a 44-quart tub takes, so there's no leftover half-bag. It arrives at field capacity with a balanced pH: open it, mix in colonized grain spawn and grow.
Pasteurized, pre-hydrated CVG substrate in the exact amount a Medium 44Q monotub takes. Open it, add one spawn bag and grow.
- 7.5 lbsPer bag
- 44QOne tub per bag
- CVGCoir, vermiculite, gypsum
- 1 bagGrain spawn needed
- 6 monthsRefrigerated, sealed
Why growers pick the 7.5 lb bag
We pasteurize every batch ourselves. It knocks back competing microbes while keeping the substrate's natural biology, which is what you want in a bulk grow.
Squeeze a handful and you'll get a drop or two, never a stream. No water to add and no guessing at moisture.
7.5 lbs is the right amount for a Medium 44Q with one grain spawn bag. Same texture, moisture and pH in every bag, so results repeat tub to tub.
Spawn to bulk in 4 steps
All you need is one fully colonized grain spawn bag and a clean 44Q monotub.
1Break up the spawn
Start with grain spawn that's completely white. Massage the bag until the grain separates into loose kernels.
2Open the substrate
Pour the whole bag into a clean monotub and crumble any clumps so it's loose and even.
3Mix it together
Combine spawn and substrate evenly, then level and lightly press the surface.
4Colonize, then fruit
Cover and leave it undisturbed until the surface is white, usually 2–3 weeks, then introduce fruiting conditions.
Bulk Growing Guide included. Our step-by-step bulk monotub guide walks you from colonized grain spawn to a fruiting tub.
How much do I need?
One 7.5 lb bag
One 7.5 lb bag fills a Medium 44Q tub on its own. For other sizes, use the amounts below.
- Small 28Q: about 4 lbs (our 5 lb bag), plus 1 spawn bag or one 32 oz jar
- Medium 44Q: 7.5 lbs (one bag), plus 1 spawn bag
- Large 66Q: 10 lbs (two 5 lb bags), plus 2 spawn bags
Keep bags sealed in a cool, dry place, or refrigerate sealed bags for up to 6 months.
Don't freeze, and avoid heat and big temperature swings that cause condensation in the bag.
Specifications
| Specification | Detail |
|---|---|
| Weight | 7.5 lbs per bag |
| Fills | One Medium 44Q monotub with 1 spawn bag |
| Base | Coco coir, vermiculite and gypsum (CVG) |
| Additives | Hydrated lime, mineral water, Azomite trace minerals |
| Treatment | Pasteurized |
| Moisture | Pre-hydrated to field capacity; no water needed |
| Spawn ratio | 2:1 to 3:1 substrate to grain |
| Works with | Rye, millet, 5-grain and other colonized grain spawn |
| Storage | Sealed, cool and dry; refrigerate up to 6 months; do not freeze |
Pick the right size
Select Bulk Substrate 7.5 lbThis product
Select Bulk Substrate 5 lbFills a 28Q tub
Select Bulk Substrate 6-PackSix 5 lb bags
Premium 5-Grain Spawn BagsSterilized grain spawn
| 7.5 lb Bag | 5 lb Bag | 6-Pack | 5-Grain Bags | |
|---|---|---|---|---|
| Use it for | One Medium 44Q tub | One Small 28Q tub | Several tubs or a Large 66Q | Your grain spawn |
| Quantity | 7.5 lbs | 5 lbs | 30 lbs (6 × 5 lb) | 2-quart spawn bags |
| Step | Spawn to bulk | Spawn to bulk | Spawn to bulk | Inoculate and colonize first |
| Pairs with | 1 spawn bag | 1 spawn bag | 2 spawn bags per 66Q | Any Select bulk bag |
Growing in a 44Q tub?The 44Q refill kit pairs this amount of substrate with a spawn bag, filters and a liner. Starting from scratch? The Complete 44Q kit includes the tub. Need spawn? Try our Premium 5-Grain or Original Rye spawn bags.
FAQ
What is in Select Bulk Substrate?
A CVG base (coco coir, vermiculite and gypsum) with hydrated lime to buffer pH, mineral water and Azomite trace minerals. It comes pre-hydrated and pasteurized.
What size tub does 7.5 lbs fill?
A Medium 44Q monotub, spawned with one grain spawn bag. For a Small 28Q use about 4 lbs; a Large 66Q takes 10 lbs.
Do I need to add water?
No. Every bag is hydrated to field capacity before it ships. Open it, break up any clumps and mix in your colonized grain spawn.
What should it look like when I open the bag?
Dark brown, moist and crumbly, with light flecks of vermiculite. If you squeeze a handful, you should get a drop or two of water, not a stream. Some clumping from shipping is normal; just break it up.
Is it pasteurized or sterilized?
Pasteurized. That reduces competing microbes while keeping the substrate's natural biology, which is the standard approach for bulk substrate. Your grain spawn is what gets sterilized.
What grain spawn can I use?
Any fully colonized grain spawn: rye, millet, 5-grain bags or grain jars. Aim for 2:1 to 3:1 substrate to grain.
Can I use it as a casing layer?
Yes. Mix it through as your bulk substrate, or spread a thin layer over colonized substrate as a casing.
How should I store it?
Keep bags sealed in a cool, dry place short-term, or refrigerate sealed bags for up to 6 months. Do not freeze.
