The Plant & Grow Mushroom Starter Block User’s Guide
By: Louis Giller | March 27, 2026
Most gardeners are already building the perfect environment for mushrooms without realizing it. Every time you spread mulch across a bed, water your vegetables during a dry stretch, or grow a leafy crop that shades the soil surface, you are creating exactly the kind of cool, moist habitat that fungi naturally thrive in.
In healthy ecosystems, mushrooms are constantly at work beneath our feet, quietly breaking down organic material like wood chips, fallen leaves, and plant debris. As they do this, they recycle nutrients back into the soil where plants and microbes can use them again.
Yet despite how important fungi are to natural ecosystems and despite how delicious and nutritious they are, most gardeners never intentionally grow mushrooms in their gardens.
This missed opportunity is where Plant & Grow mushroom starter blocks come in to save the day
Plant & Grow blocks are the easiest and fastest way to introduce edible mushrooms into your garden. If you think of them as mushroom transplants, the concept becomes immediately familiar. Just as gardeners buy tomato starts or flower bulbs to skip the seed stage, Plant & Grow blocks allow you to plant a living mushroom organism that is already growing and ready to establish itself outdoors.
Because the mycelium inside the Plant & Grow is already alive and active, you can often harvest mushrooms in weeks, not months, making this one of the fastest ways to produce food in the garden.
What are Plant & Grow mushroom starter blocks?
Plant & Grow blocks are made of fully colonized and hydrated mushroom substrates, meaning they contain a thriving network of mycelium growing throughout a nutritious woody base material.
Mycelium is the main body of the fungus. If mushrooms are the fruit of the organism, mycelium is the root-like network that lives underground, spreading through organic materials and digesting them for nutrients. It can be helpful to use a plant analogy to understand this: mushrooms are to mycelium as apples are to an apple tree.
In the garden, this network grows through materials like wood chips, straw, leaf litter, and decomposing branches. Studies in soil ecology consistently demonstrate that the mycelium releases enzymes which break down complex (tough to digest) compounds like lignin and cellulose, gradually transforming organic debris into nutrients that support soil life.
Plant & Grow blocks are simply all those dynamics in a neat package that, with the right environmental conditions, are ready to perform. The process is simple:
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Dig a small hole in your garden bed or mulch layer.
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Remove the Plant & Grow from its plastic packaging and place it in the hole.
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Cover it with soil, compost, leaves, or wood chips.
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Water the area and keep it moist.
We often say that Plant & Grow mushroom starter blocks are the seedlings of the mushroom world.
Why grow mushrooms in your garden?
When people first encounter the idea of growing mushrooms outdoors, they often assume it’s complicated or technical. The truth is that mushrooms have always been part of the garden ecosystem; we just haven’t been paying attention to them. Worse yet, sometimes people see mushrooms as pests.
Unlike vegetables, mushrooms do not compete for sunlight, and they do not rely on the same soil nutrients that plants do. Instead, most garden-friendly mushroom species are decomposers (saprophytes), meaning they feed on organic materials such as wood chips, straw, and leaf litter. This process leads to more stable soil, better water retention, and reduced need for fertilizers over time
Mushrooms can thrive in places where traditional crops might struggle, including the shaded understory beneath large plants or the mulched pathways between garden beds.
For gardeners, this creates an exciting opportunity.
Instead of dedicating prime planting spaces to mushrooms, you can simply add them to areas that already exist in the garden but often go unused, the in-between spaces. Years of putting this into practice shows that mushrooms effectively create a second harvest layer beneath plants and thrive in shady areas that are often seen as poor places for cultivation.
Fungi play a major role in soil health. As mycelium spreads, it breaks down organic matter and supports a complex network of organisms from the bottom of the food chain all the way up. Scientists estimate that roughly 80–90% of plants form relationships with fungi, exchanging sugars for nutrients and water that the fungi help access in the soil. These mycorrhizal relationships are essential. While most edible garden mushrooms are fully decomposers rather than mycorrhizal partners, their activity still indirectly supports soil health, plant health and the ability of mycorrhizae to proliferate.
Plant & Grow blocks have the ability to produce multiple crops in most cases, but at some point they will give in to decomposition. What’s left behind is known as Spent Mushroom Substrate (SMS) and is extremely valuable for the gardeners. Research has shown that SMS can increase moisture retention, improve soil structure, stabilize temperature, enhance microbial activity and slowly release valuable nutrients back into the soil. This may reduce the need for more external inputs such as synthetic fertilizers.
Do you have a nematode (roundworm) problem? You might, but not even know it.
Some of these tiny creatures can cause root rot and reduce crop vigor, while you scratch your head wondering what the problem is. Oyster mushrooms can be grown using multiple methods including Plant & Grow blocks and are about the most vigorous species available. They are capable of trapping, poisoning and consuming nematodes in the surrounding soil.
Where Plant & Grow blocks work best
The best locations for planting Plant & Grow blocks are the same types of environments where mushrooms naturally appear outdoors.
These areas are typically shaded or partially shaded, contain organic matter, and retain moisture more easily than exposed soil.
In most gardens, excellent planting locations include:
- Beneath tall vegetable crops such as tomatoes, peppers, or kale
- Under sprawling plants like squash or cucumbers
- Along the edges of raised beds
- In mulched perennial beds
- Under other perennial shrubs and trees
Plants themselves help mushrooms thrive by creating a humid microclimate near the soil surface. Their leaves provide shade and slow down evaporation, allowing the soil and mulch layer to retain moisture longer. Because of this, mushrooms often perform well when they are planted alongside other garden plants rather than separately.
This practice is called companion planting with mushrooms, and it allows gardeners to integrate fungi into the same spaces where vegetables and flowers already grow.
If you want to explore specific pairings and design strategies, we recommend reading our full guide:
When to plant Plant & Grow blocks
Outdoor mushrooms follow seasonal temperature patterns much like vegetables do, which means timing your planting according to temperature can significantly improve success.
Mycelium becomes metabolically active once average daily temperatures rise above about 50°F, allowing the fungal network to expand through surrounding soil and organic material.
For many temperate climates, you can use Plant & Grow all season long with expected harvests in the cooler parts of the growing season. Put your Plant & Grow into the ground as soon as it’s workable, and throughout the season.
As long as there is moderate temperatures and consistent moisture, conditions that fungi particularly enjoy, you’ll get harvests of mushrooms.
Rather than memorizing specific calendar dates, it can be helpful to think of mushrooms in terms of temperature groups.
Cold-loving species will fruit in cooler conditions between roughly 40 and 65°F, moderate species will produce mushrooms between 55 and 75°F, and warm-weather species produce best between 65 and 90°F. To complete the picture, it’s also helpful to understand how mushrooms grow in your climate.
Plant & Grow also works well with North Spore’s dedicated outdoor mushroom bed, the MycoSphere. The MycoSphere helps dial in growing conditions such as moisture, shade, and temperature control helping achieve a level of consistency and yield that can be difficult to attain in some climates. The MycoSphere can also help extend the season in cooler climates, or make it more suitable for mushroom growing in hotter climates.
For a more detailed explanation of planting windows based on climate patterns and regional conditions, see our full guide:
Choosing your Plant & Grow species
Plant & Grow blocks are available in a range of mushroom species that will fruit in different seasonal conditions and garden environments. If the ground is workable, you can put your Plant & Grow blocks in the ground. Fruiting will depend on temperature and humidity of your microclimate:
Cold-fruiting species (40–65°F)
These mushrooms fruit in cooler temperatures:
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From $29.99 -
From $29.99
Moderate-temperature fruiting species (55–75°F)
These mushrooms are versatile and will fruit throughout the main growing season:
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From $29.99 -
From $29.99 -
Warm-fruiting species (65–90°F)
These species prefer warm summer conditions and benefit from the humidity created by dense garden foliage and will fruit in warm/hot conditions:
What to expect after planting
One of the most exciting aspects of growing mushrooms outdoors is how quickly they can appear once conditions are right.
Unlike vegetables, which typically require months between planting and harvest, mushrooms can emerge rapidly once the fruiting process begins. Some species are capable of doubling in size within a single day, which is why clusters sometimes seem to appear overnight after rainfall.
While there are a few species such as Reishi that can take a number of months, most will appear within weeks.
Blocks will typically rest between flushes (crops) for at least a few weeks and then will often fruit again when storms or big temperature shifts occur. This can happen numerous times. Blocks can even go dormant for a whole winter and produce again in the spring!
Frequently Asked Questions
Is it safe to grow mushrooms in the garden?
Yes. Plant & Grow blocks contain cultivated edible mushroom species, so you know exactly what was planted and what to harvest. These are easy to ID and differentiate from other mushrooms that might appear.
If you have even the slightest question as to whether what you’re seeing is what you planted, please take clear pictures from multiple angles and reach out to us.
Will mushrooms harm my plants?
No. These species are decomposers that feed on organic material like mulch and wood chips rather than living plant roots. In fact, their activity often improves soil structure and nutrient availability. Other fungi that cause conditions like Powdery Mildew, Black Spot or Blight are very different organisms.
What if my animals eat them?
Usually, pets are just not interested in mushrooms at all. However, the curious dog has been known to nibble. These are culinary mushrooms that are generally regarded as safe for animals to consume. When raw, these mushrooms are harder on the digestive system, so some mild illness or discomfort is possible.
It’s worth noting that just because you see another creature chomping on a mushroom, that doesn’t mean said mushroom is edible for you!
Is it really as easy as planting a transplant?
In most cases, yes. As long as the planting site stays reasonably moist and shaded, mushrooms will usually establish themselves with very little intervention.
What if mushrooms appear elsewhere in my garden?
This often means the mycelium or spores have successfully spread into nearby mulch or organic material. Many gardeners consider this a sign that the fungal network has become established and healthy. More mushrooms is a win in our book.
A garden that feels more alive
For a long time, mushroom cultivation has been framed as something technical or mysterious, something that happens indoors in controlled environments. Yet outdoors, mushrooms grow naturally wherever organic matter, moisture, and shade come together.
Plant & Grow mushroom starter blocks simply make it easy to bring that natural process into your garden intentionally. By planting them alongside your vegetables and flowers, you transform ordinary garden spaces into living ecosystems where fungi, plants, and soil organisms work together. And once you see mushrooms appearing beneath your tomatoes or along your garden paths, it becomes clear that they were meant to be there all along.