How to Grow Mushrooms in your NZ Garden

Updated: Sep 12, 2021

Outdoor mushroom patches are a brilliant way to increase soil health, and get healthy organic mushrooms in the garden! There are two types of edible and useful mushrooms that can be easily grown in your garden. Both grey oyster mushrooms and king stropharia mushrooms are wood decomposers and can quickly break down biomass such as fresh wood-chips into healthy, rich soil. We may as well start with the king ...

King Stropharia

(Stropharia rugosoannulata) a.k.a. Wine Cap a.k.a. Burgundy Mushrooms a.k.a. Garden Giant

King Stropharia has many names and many uses. It is extraordinary in that it is a primary and secondary decomposer, and has many beneficial properties, including the ability to trap and eat some root-eating nematodes, boost the growth of certain plants such as corn, benefit local bee health & immunity, attract earthworms, and even filter water in an aquaponic or permaculture setting. King stropharia is an edible mushroom that is easily identified in the garden by its burgundy-wine coloured cap in its younger stage. This species tolerates full sun and can last for years by adding fresh biomass every year for nutrients.

How to set up a King Stropharia patch

Ideally, you would like hardwood sawdust/ wood-chip** -- less than 25% fresh pine/ conifer wood-chip, that is no older than 6 months -- be sure your wood-chip is wood-chip and not bark. Scrape the intended patch area down to soil or low-cut grass, then add a 2-4 inch layer of fresh wood chip followed by a layer of your king stropharia spawn, followed by another thicker layer of wood chip about 6-12 inches (for larger patches with lots of spawn repeat previous steps, layering spawn with wood chip until all spawn is used). Bed should be no thicker than 24 inches thick. Hand spread at a minimum of 1kg of spawn per square meter. We strongly recommend using 2kg of spawn per square meter, this higher spawn rate is much more likely to establish, survive the winter, and produce mushrooms the first year!

Once you install the king stropharia patch, keep it undisturbed for about 4-6 months. Planting crops normally through the area is fine. Inter-planting corn, zucchini, squash and pumpkin in the mushroom patch is especially good for both the crop and the mushrooms. We have noticed pumpkin crops make a humid micro climate under their leaf canopy leading to abundant fruiting! After about four to six weeks you can check to see how the mycelium is growing by digging a small hole into the wood chip. You should see thick white mycelium starting to grow off of the spawn onto the fresh wood chip, like the photo above. Keep it well-watered through summer, same as watering your veggie garden is sufficient. You can check the moisture content of the wood chip easily by scraping back 1 inch of chip and you can visually see if it is damp by the darker colour of the wood chip. Before winter, you will want to add a thick layer of wood chip, about 3-5 inches, to protect from frost: over winter the mycelium will retract down to protect from frost, and grow back again in spring. Adding any synthetic fertilisers to wood chip is not advised.

>> Order King Stropharia spawn for your garden here - shipped NZ-wide.

Harvesting King Stropharia

King stropharia can grow to the height of 30cm with a cap size of roughly 30 cm, hence the name Garden Giant. They are best for cooking if harvested early, as soon as gills are visible -- before the gills begin to darken in colour to a purple- black colour ... and before the bugs get in! While they have a strong red-wine-meaty flavour, they begin to get bitter with age. Everything can be eaten from the cap to the stem, the stems tend to have an asparagus like texture. Make sure you properly identify any mushrooms before consuming!!

Oyster Mushrooms

(Pleurotus pulmonarius or NZ-Native Pleurotus Parsonsiae) a.k.a. Pheonix oyster and Velvet oyster

Oyster mushrooms are known to boost the immune system, being extremely nutrient dense and full of antioxidants. They are high in amino-acids, important vitamins and minerals as well as fibre. Oyster mushrooms are full of beneficial polysaccharides and have recently been reported to contain specific compounds known as immunomodulators that help regulate the immune system. There are even ongoing research studies indicating cancer-fighting and anti-inflammatory properties.

Oyster mushrooms are a great addition in the kitchen, too! They are often found in Asian cuisine and are a great umami flavour addition to a vegetarian/vegan diet. These mushrooms are unique in texture as they can get crunchy like a chip!

>> Learn hot to cook your very own perfect crispy Oyster Mushrooms here.

Oyster mushrooms are an extremely fast-coloniser that produce well on a wide range of substrates. Oyster mushrooms contain natural enzymes that break down foreign substances such as petroleum oils, PCBs, pesticides and herbicides, and are even being used in a range of 'mycoremediation' projects such as cleaning up charred toxic-debris from commercial buildings and households after these recent large-scale fires. Mycoremediation could potentially be used on a large-scale as one of the solutions to naturally help clean up NZ waterways by setting up low-tech filtration systems to break down harmful bacteria and toxins from farm run-off.

How to make an Oyster Mushroom bed: Outdoor patches can start producing mushrooms in as little as 40 days from setting up your patch. Building the patch/bed is simple and virtually the same as making a King Stropharia mushroom patch. First, break up the spawn (mushroom seed/ starting culture) and spread out the spawn evenly in the desired patch site, then add a layer of woodchip/straw (substrate) on top of the spawn. It is important to keep the patch well-watered for the first month and prevent it from drying out. Plants/ veges can be planted directly into the patch and are generally beneficial to producing mushrooms by providing shade and keeping humidity higher under the leaf canopy. The mushroom will rapidly break-down dead plant material to build healthy soil: enzymes secreted by the mushroom will be washed through the soil and help break down any residual pesticides/herbicides and other contaminants in the soil encouraging beneficial bacteria.

>> Order ready-to-use oyster mushroom spawn for your Kiwi-garden here.

Harvesting Oyster Mushrooms:

Typically, it is best to harvest oyster mushrooms when they go from convex to concave, basically from turning down to turning up. In the outdoor-patch setting, you should try to get to them before the bugs do!! Keep a close eye on them when they begin to pop up (as they double in size every day) and pick them as early as possible.

As always, please properly identify ALL mushrooms before consuming!!

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