How to grow mushrooms without a kit
You need spawn and a substrate. Grain spawn cannot fruit on its own, so it has to be mixed into a substrate such as pasteurized straw or sawdust. Cornell says straw and sawdust can fruit in as little as 3 to 4 weeks.
What changes when there is no kit
A kit is a finished block. Without one, you make the block. North Spore says grain spawn is not an all-in-one kit, and it has to be mixed with bulk substrate before it can fruit.
Cornell's small farms program breaks cultivation into four main steps, and it defines a substrate as the material the mushroom grows on and feeds from. Which substrate you use decides how long you wait.
How long each substrate takes
| Substrate | Typical time |
|---|---|
| Logs and stumps | 6 to 18 months |
| Wood chips | 2 to 6 months |
| Straw and sawdust | As little as 3 to 4 weeks |
Clemson's extension factsheet gives species ranges on logs: oyster can fruit in as little as 3 months, and shiitake can take up to 18 months.
The straw route
Cornell says straw allows lower-intensity treatments that do not need sterile spaces. One method it describes is soaking in lime, which raises the pH of the straw to 12 or 13. It also says straw logs have to be fruited indoors, because bugs lay larvae in them if they are grown outside.
North Spore's garden guide says oyster is the best choice for straw.
Our read on whether to try it
This section is our opinion, not a source's. If this is your first grow, buy a kit. A kit teaches you the fruiting stage, and it skips the substrate work. Once you have harvested a few flushes, straw is a reasonable next step. We have not run the straw method ourselves, so we are not giving amounts or step-by-step recipes here.
The substrate recipe calculator helps you work out amounts for a sawdust and soy hull mix. See growing mushrooms outdoors for logs and beds, and how to grow mushrooms at home for the kit method.
Keep reading
- Mushroom growing glossary: substrate, spawn and other terms
- What is mycelium?: the living part of the mushroom
- Substrate recipe calculator: sawdust, supplement and water by weight
Back to How to grow mushrooms at home
Common questions
Can I grow mushrooms from grain spawn on its own?
No. North Spore says grain spawn is not an all-in-one kit, and it must be mixed with bulk substrate before fruiting.
What is the easiest substrate to start with?
Cornell says straw allows lower-intensity treatments that do not need sterile spaces, and North Spore says oyster is the best choice for straw.
How long does growing without a kit take?
Cornell says straw and sawdust can take as little as 3 to 4 weeks, wood chips 2 to 6 months, and logs and stumps 6 to 18 months.
Is growing without a kit cheaper?
We do not have a sourced cost comparison, so we will not give a number. Spawn, substrate and any equipment add up, so work out your own costs before you decide.
Sources
- Grain Spawn FAQ, North Spore. Checked November 11, 2026.
- Producing Specialty Mushrooms: Outdoor vs Indoor Systems, Cornell Small Farms Program. Checked November 11, 2026.
- Four Methods of Commercial Cultivation, Cornell Small Farms Program. Checked November 11, 2026.
- Specialty Mushroom Production for South Carolina, Clemson Cooperative Extension. Checked November 11, 2026.
- How To Grow Mushrooms Outside in Your Garden, North Spore. Checked November 11, 2026.
How this page is checked
Cedrick Reese wrote this page from North Spore's grain spawn FAQ and garden guide and from Cornell and Clemson extension material on substrates. The section called our read is marked as opinion, and everything else is attributed. We are not giving step-by-step spawn recipes here, because we have not run those grows and do not want to hand you untested amounts.