Monotub Upgrade Kit For 4 LB All-in-One Grow Bag

Name: Monotub Upgrade Kit For 4 LB All-in-One Grow Bag
Brand: Midwest Grow Kits
SKU: UP4
Price: 19.99 USD
Availability: InStock

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$19⁹⁹

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Turns a colonized 4 lb All-in-One grow bag into a 28-quart monotub grow. Includes Grower's Select tub, 2 lbs Select Bulk Substrate, 4 filter disks, 4 plugs, fitted liner and spray bottle. Bag sold separately.

Description

The Monotub Upgrade Kit turns a colonized 4 lb All-in-One grow bag into a 28-quart monotub grow. It adds a Grower’s Select tub, 2 lbs of Select Bulk Substrate, filter disks, plugs, a fitted liner and a spray bottle — so your bag spawns a bigger, flatter fruiting surface instead of fruiting in the bag.

Grower's Select 28Q monotub with filter disks, plug and liner beside a fully colonized All-in-One grow bag on a light oak counter

Your bag is colonized. Now give it room.

Break a 4 lb All-in-One bag into a 28Q tub with 2 lbs of fresh substrate for a wider, flatter fruiting surface. Everything but the bag is in the box.

Nothing to drill or cut: the tub comes ready for the filter disks and plugs. The All-in-One bag is sold separately.

For 4 lb All-in-One bags
28Q monotub
2 lb substrate included
No drilling

28 qtGrower’s Select tub
12"Cube tub
2 lbsSelect substrate
4 + 4Filters + plugs
LinerCustom fitted, food-safe HDPE, BPA free

Why upgrade your bag to a tub

Lined black Grower's Select 28Q monotub base with the lid off, fruiting golden-capped mushrooms across the full surface

A bigger fruiting surface

Spreading the colonized bag across a 12" × 12" tub floor gives mushrooms far more surface to pin from than the inside of a bag.

Monotub Upgrade Kit contents on a wood table: 28Q tub with clear lid, bag of Select substrate, liner, spray bottle, filter disks and plugs

Everything but the bag

Tub, 2 lbs of Select Bulk Substrate, four filter disks, four plugs, a fitted liner and a spray bottle in one box.

Clean Grower's Select 28Q monotub with its clear lid on, drying on a towel by a kitchen sink beside four filter disks and a plug

No drilling, built to reuse

The holes come pre-cut for the disks and plugs. The thick-walled Grower’s Select tub is yours to wash and run again.

What’s in the kit

Grower’s Select 28-quart monotub fruiting chamber (12" × 12" × 12")
2 lbs Midwest's Select Bulk Substrate
4 monotub filter disks
4 humidity-regulating hole plugs
Custom fitted liner, food-safe HDPE and BPA free
Misting spray bottle

Sold separately: the 4 lb All-in-One mushroom grow bag.

How to use it

Four steps from a colonized bag to a fruiting tub.

White mycelium spreading through the grain layer of an All-in-One grow bag on a warm shelf

1Colonize the bag

Grow out your 4 lb All-in-One bag until it’s fully colonized.

Gloved hands mixing white colonized spawn through coco coir in a lined Grower's Select 28Q monotub, emptied grow bag beside it

2Spawn to bulk

Fit the liner, break the bag into the tub, mix it evenly with the 2 lbs of Select substrate and level the surface.

Grower's Select 28Q monotub with its lid on and holes plugged, the surface inside covered in white mycelium

3Colonize the tub

Seal the air holes with the plugs and let the tub colonize, warm and undisturbed, until the surface is white.

28Q Grower's Select monotub with its clear lid on, fruiting golden-capped mushrooms

4Fruit

Swap the plugs for the filter disks, give the tub indirect light and mist the walls with the spray bottle to keep humidity up.

Bag stage walkthrough: the All-in-One Grow Bag Guide covers inoculation, colonization and break-and-shake timing with real grow photos.

Bag vs. tub: what changes

Dense flush of golden-capped mushrooms covering the full surface of an open Grower's Select 28Q monotub

A full-surface flush in the 28Q

Same bag, more room to fruit

In the bag, mushrooms pin only from the top of the substrate. In the tub, the same colonized bag plus 2 lbs of fresh substrate becomes a wide, level bed with filtered air through the lid and a liner that keeps pins off the walls.

Fits a 12" × 12" footprint
Liner helps prevent side pinning
Plugs to colonize, disks to fruit

What you add

One fully colonized 4 lb All-in-One grow bag.

Don't have one yet? The All-in-One Starter Kit comes with the bag and this tub setup in one box.

Specifications

Specification	Detail
Tub	Grower’s Select 28-quart monotub, 12" × 12" × 12"
Substrate	2 lbs pasteurized Select Bulk Substrate
Air exchange	4 filter disks, 4 hole plugs
Liner	Custom fitted, food-safe HDPE, BPA free
Also included	Misting spray bottle
Works with	4 lb All-in-One mushroom grow bag (sold separately)
Modifications	None — no drilling or cutting

Build out your All-in-One grow

Monotub Upgrade Kit for the 4 lb All-in-One grow bag

Monotub Upgrade KitThis product

4 lb All-in-One mushroom grow bag with its box

4 lb All-in-OneThe bag it fits

All-in-One Mushroom Monotub Starter Grow Kit

AIO Starter KitBag + tub in one box

Grower's Select 28Q monotub fruiting chamber with filter disks and liner

Grower's Select 28QJust the tub

	Upgrade Kit	4 lb Bag	Starter Kit	28Q Tub
Use it for	Moving a 4 lb bag to a tub	Your first bulk grow	Bag and tub in one box	A spare or second tub
Contents	28Q tub, 2 lbs substrate, filters, plugs, liner, spray bottle	1.75 lbs grain + 2.25 lbs CVG	4 lb bag, 28Q tub, 2 lbs CVG	Tub, filter disks, liner
Fruit it	In a 28Q monotub	In the bag	In a 28Q monotub	In a 28Q monotub
You supply	A colonized 4 lb bag	Spores or liquid culture	Spores or liquid culture	Spawn and substrate

Starting from scratch?The Complete 28Q Monotub Kit includes the tub, grain spawn and substrate in one box, and the All-in-One Starter Kit pairs a 4 lb bag with this tub setup. Need genetics? Browse our liquid culture syringes or spores from Spore Genetics.

FAQ

Does this include the All-in-One bag?

No. The bag is sold separately — this kit adds the tub, substrate and accessories to turn a colonized bag into a monotub grow.

When do I move the bag to the tub?

Once the All-in-One bag is fully colonized. Then break it up into the lined tub and mix it with the 2 lbs of Select substrate.

Why move to a monotub instead of fruiting in the bag?

A tub spreads the colonized substrate into a wide, flat surface with controlled fresh air and humidity, which gives mushrooms more room to fruit.

Do I need to drill holes?

No. The tub is ready for the included filter disks and plugs.

When do I use the plugs and when do I use the filter disks?

Keep the holes plugged while the tub colonizes. Once the surface is white, swap the plugs for the filter disks to give the tub filtered fresh air for fruiting.

What is the liner for?

The custom fitted liner is food-safe HDPE and BPA free. It helps prevent mushrooms from pinning down the sides of the tub and makes cleanup simple.

Can I reuse the tub?

Yes. The tub, plugs and filters can be reused for future grows.