Substrate Guide

Millet vs Corn vs CVG — Which Substrate Should You Choose?

Three substrates. Three different jobs. Here's what each one does and which is right for your grow.

Written by the Cloud920 mycologist Last updated: April 2026 4 min read

Starting out?

Millet

Heavier yields?

Corn

Ready to fruit?

CVG

At a Glance

Millet Corn CVG
Type Grain spawn Grain spawn Bulk fruiting substrate
Purpose Colonise mycelium Colonise mycelium Fruit mushrooms
When you use it First step First step After grain is colonised
Colonisation speed Fast (2–3 weeks) Moderate (3–4 weeks) 1–2 weeks after mixing
Mycelium density Good Dense and robust N/A
Yield potential Good High — multiple heavy flushes Depends on grain quality
Best for Beginners, fast turnaround Experienced growers, yield focus All growers (used with grain)
Compatible species All grain-colonising species All grain-colonising species Cubensis & most gourmet
Available sizes 2000ml / 4000ml 2000ml / 4000ml 2000ml / 4000ml

Millet — Best for Beginners

Grain spawn

Millet's small kernels mean a large surface area — more places for mycelium to grip after inoculation. The result is fast, even colonisation that gives you clear feedback quickly.

For a first grow, seeing white mycelium spreading through your bag within 5–10 days is reassuring. Millet gets you there faster than any other grain.

Choose millet if:

  • It's your first grain bag
  • You want fast colonisation and quick feedback
  • You're running multiple bags and want a fast turnaround
  • You're testing a new liquid culture and want to confirm it's viable quickly
Shop Millet Grain Bags

Corn — Best for Yield

Grain spawn

Corn colonises a bit slower than millet, but the reward is denser, more robust mycelium. More nutrients per kernel means a stronger fruiting block and heavier, more consistent flushes.

Growers who switch from millet to corn often notice the difference in their harvests — thicker pins, beefier fruits, and flushes that keep coming.

Choose corn if:

  • You've grown on grain before and want to improve your yields
  • You want denser mycelium for a more vigorous fruiting block
  • You're happy to wait an extra week for colonisation
  • You want to maximise your number of flushes
Shop Corn Grain Bags

CVG — For Fruiting

Bulk substrate

CVG (coco coir, vermiculite, gypsum) is not a grain spawn — it's a bulk fruiting substrate. You don't inoculate CVG with liquid culture and wait for it to colonise from scratch. Instead, you take a fully colonised grain bag (millet or corn), break it up, and mix it into the CVG to create a fruiting block.

CVG provides the moisture, aeration, and nutrition your mycelium needs to transition from colonisation to fruiting. It's the substrate where your mushrooms actually grow.

Choose CVG if:

  • You already have colonised grain spawn and need a bulk substrate to fruit into
  • You want to skip DIY substrate prep entirely — our bags are pre-sterilised and ready to use
  • You're growing Psilocybe cubensis or most gourmet species
Note: CVG is not ideal for wood-loving species like lion's mane, P. azurescens, or king oyster. These need a hardwood-based substrate.
Shop CVG Substrate Bags

How They Work Together

Most grows use two bags — a grain bag and a CVG bag. The grain bag is your spawn. The CVG bag is your fruiting block. Together they give you the full grow cycle without a pressure cooker, flow hood, or any special equipment.

1

Grain bag (millet or corn)

  • Inoculate with liquid culture
  • Wait for full colonisation (2–4 weeks)
  • Break and shake at 30% colonisation
2

CVG bag

  • Mix in colonised grain spawn
  • Wait for full colonisation (1–2 weeks)
  • Fruit and harvest
How to Inoculate a Spawn Bag — Full Guide

Which Should You Buy First?

1

Complete beginner

Start with a millet grain bag and a liquid culture. Once it's fully colonised, you can fruit it directly in a monotub or add a CVG bag for a larger harvest.

2

Want the full setup

Order one millet or corn bag + one CVG bag. That's everything you need for a complete grow from inoculation to harvest.

3

Experienced grower

If you've already grown on millet and want to step up, try corn. The denser mycelium is worth the extra week.

Ready to order?

All three substrates. Prepared in-house.

Organic A-class ingredients, pressure-sterilised, tested for contamination. Ships fast across Europe from the Netherlands.

Millet Bags Corn Bags CVG Bags
Browse Liquid Cultures Not sure? Contact us

Related guides

Millet vs Corn — Deep Dive

The full comparison: speed, density, and which to choose.

What Is CVG Substrate?

How coco coir, vermiculite, and gypsum work together.

How to Inoculate a Spawn Bag

Step-by-step inoculation with a liquid culture syringe.

Liquid Culture vs Spores

Which inoculation method gives you the cleanest grow?