HOW TO GROW MUSHROOMS: A BRIEF INTRODUCTION
To find out more about growing mushrooms enrol in Mushroom Production BHT310 (100 hours duration) studied by Distance Education from anywhere in the world. This is a serious course for the enthusiast: amateur, or commercial grower.
This course is unique and has been evolving over 20 years with a serious revision every 1 to 2 years, since it was first developed. The most commonly grown mushroom worldwide is Agaricus (The Champignon); and for that reason, more attention is given to that type of mushroom. Other commercially grown mushrooms are reviewed in most lessons as well, in order to give the student a broad understanding of how to cultivate all types of commercial fungi. As the student develops this foundation in understanding fungal growth, and commercial techniques; their capacity to grow any type of edible fungi will increase.
This course improves your ability to grow mushrooms on either a small or large scale; and both broadens and deepens your knowledge of growing, harvesting, marketing, storage, pest and diseases and even ways of cooking and using mushrooms. Study now and learn at home.
Growing mushrooms at home can be easy, rewarding and not nearly as difficult as you might think. The common mushroom (Agaricus sp.) grows easily on compost, held in either trays, bags, boxes or raised beds.
Four Easy Steps:
The basic steps in the growth cycle are:
1. Making the Compost
Raw materials for the compost are mixed together, moistened and composted.
The compost is placed in containers or beds, under cover, and spawn is added. Conditions are controlled to achieve optimum growth of the spawn so that it can fill the compost with mycelia over a period of weeks.
Casing involves placing a layer on top of the compost, to bring about environmental conditions which encourage the formation of fruiting bodies (ie: The mushrooms which are eaten).
After several weeks, the first crop is picked. Further crops occur every week or so (These are called flushes). After a month or two, the flushes decline and the compost should be discarded and the process started again.
NB: You can avoid the first step by purchasing a mushroom kit from a nursery or chain store, with the compost already prepared for you.
MAKING YOUR OWN COMPOST
If you want to grow a lot of mushrooms, you may decide to make your own compost. The quality of mushroom compost has a very big affect on the success of a crop.
A three stage operation is normally used in making mushroom compost:
Stage 1. (Preconditioning)
The raw materials are mixed, moistened & allowed to undergo some initial decomposition in a large heap. A mixture of manure and straw usually makes up the bulk of the compost. Keep moist but not over wet during this stage. To every 100kg of straw and manure add 1.5kg of gypsum and 1 2kg of urea or ammonium sulphate. If composting successfully, the centre of the heap will become hot and it's colour will darken within two weeks.
Stage 2. (Composting)
Decomposition is now hastened by turning the heap every 2 3 days and watering when necessary to keep it moist.
Stage 3. (Peak Heating)
After a further 2 4 weeks, the compost is moved indoors (into a shed) where temperature & oxygen content are better controlled, to complete the composting. The temperature should be kept between 40 and 60 degrees centigrade in the heap. This is done by making the heap smaller or larger, turning it frequently and monitoring the temperature carefully with a thermometer. At these temperatures pasteurization should occur, killing off harmful pests & diseases.At the end of this stage, the compost will be uniform throughout, have a non greasy texture and will be dark brown (perhaps with a flecking of white fire fang fungus) throughout. There should be no trace of ammonia smell which occurred earlier.
Mushroom compost will grow mushrooms best if used as soon as possible after it has been prepared.
Spawn production is a very sophisticated scientific process, hence most mushroom growers do not produce their own spawn. They buy it from a few, specialized producers who are able to maintain standards and ensure freshness.
Spawn varies in colour depending on age. Very fresh spawn sometimes does not even show any sign of the white mycelium growth of the fungi. If spawn is very densely covered by the white fibrous mycelium growth, this may indicate it is too old. In both of these cases, it will generally still give an acceptable result.
Always check spawn for visible signs of non mushroom growth. Other fungal mycelia may vary in colour or growth form. If it appears that there are two different types of mycelia growing, then the spawn should not be used.
There are various different strains of spawn, each giving different types of mushrooms. (white, off white, brown, cream etc). A spawn supplier will usually offer different types of spawn, and will advise on which is the best for your situation.Some mushroom farms also run laboratories which produce and sell spawn.
Spawning is carried out as follows:
*Grains of spawn should be separated from each other as thoroughly as possible as the spawn is spread over the surface of the compost.
*Spawn should be mixed evenly throughout the compost.
*Conditions should be kept as sterile as possible (Wear clean clothing and footwear, wash your hands before carrying out spawning, tools should be sterilized in, formalin or some other antiseptic which will not damage the mushroom).
*Do not add spawn to compost while the temperature of the compost is above 30 degrees centigrade. (34 degrees will kill the mycelia).
*If there is any ammonia present in the compost (ie: through composting being incomplete), the mycelia is not likely to grow.
The optimum temperature for the mycelia to grow is 25C.
Three or four days following spawning, a cottony growth should appear around the grain, and depending on conditions, the mycelia should have thoroughly grown through the compost after about 2 weeks.
Once the mycelia have grown to this point it will generate increased heat in the compost. It is important that the temperature be held down, and this is normally done by ventillation or by a cooling system.
The mycelia which grow throughout the compost, following spawning is the vegetative growth stage of the mushroom. Actual edible mushrooms are the fruiting stage of growth, and as such, they do not begin to form until something happens to stimulate a change from vegetative growth to fruiting body formation.
By putting a layer of material (the process is called casing), over the top of the compost, this required change is stimulated and mushrooms begin to form.
WE DO NOT FULLY UNDERSTAND WHY CASING CAUSES THIS CHANGE TO OCCUR.
There are many different materials which can be used: pulped paper, compost, cow dung, old/used mushroom compost, peat and sphagnum mosses, or mixtures of any of these.
The casing material is usually high in organic material, and should be free of pests & diseases (ideally sterilized).
Casing material can be sterilized by drenching in formaldahyde solution or by pasteurization at 60oC for 3 hours.
Casing material should have an open texture, not repel water (as do some organic materials) when dry, and have a pH between 6.5 and 8.
Casing material should normally be as wet as possible when applied to the beds and is usually applied to a depth of 25 to 50cm over the top of the compost.
Casing material is normally applied about 2 weeks after the spawn has fully run through the compost. (NB: When spawn has fully run, there will be a visible mass of grey white fibrous mycelia through the compost).
Test the depth at frequent intervals to be certain that the casing is being applied evenly.
Pests & Diseases
A range of diseases and insect pests can attack mushrooms.
Prevention is the best way of controlling pests & diseases in mushrooms. It is absolutely essential to keep your growing area clean. Use clean tools and equipment, clean compost, and pure, uncontaminated spore from a reliable source. If any sign of a pest or disease appears, it should be controlled immediately, as all too often, the conditions which are ideal for mushroom growth are the same conditions which are ideal for rapid spread of the pest or disease problem.
It is difficult to find any safe pest or disease sprays to use on mushrooms when they are close to harvest. One possibility might be herbal sprays (ie: Sprays made from herbs). These are be relatively safe and you could spray and eat the mushroom immediately. Though many herbal sprays are mild in their effect on pests or diseases, they may be good enough in the home situation.
There is no known work done on the use of such sprays, and for this reason, we would suggest only small quantities be tried at first. Possible side affects might be:
The spray changing the flavor of the mushroom.
Spray damage to the mushroom tissue.
Has repellent properties for insects as well as certain fungicidal properties. A spray will last for up to 10 days. Preparation....Crush 90gm of garlic. Pour 10ml. of non aromatic oil over the top. Soak for 48 hrs. Add this to a soap solution (about 10 gm of soap in 500ml water). Leave for one day then strain. Store in sealed containers. Use 1 part mixture to 100 parts water or less depending on situation.
A herb tea or infusion can be prepared by simply pouring hot water over fresh or dried herbs. Teas made this way from certain herbs can be used as sprays to control certain pest & disease problems. Lavender spray can be used against flies which can be a major problem on mushrooms.
There are three different stages at which mushrooms may be harvested:
These are unopened (gills are not exposed), and will remain unopened throughout until they are eaten. You get less crop when you harvest at the button stage, and the flavour is not as good as with developed fruits, however they are often prefered for their appearance if nothing else.
These are where the veil has opened or will probably open before it is used. These mushrooms still have a rounded cap, and are sometimes preferred to the fully opened mushroom.
- FULLY OPENED MUSHROOMS OR FLATS.
These are when the gills are exposed, and the cap has flattened. They are larger. The gills are at first pink, but become dark brown as time goes on.
- Pick each mushroom with an upward twisting motion.
- Break them off at the casing surface.
- Do not pull with pieces of casing being lifted still attached to the mushroom.
- Following picking, there should be as few holes or stumps of mushrooms left in the bed, as is possible.
- Brushing mushrooms after picking, to remove compost and casing material.
- These can cause bad discoloration of the cap.
- Mushrooms left too long before picking can over mature...as little as 12 hours can make a significant difference.
Recycle Mushroom Compost
When you have finished with a mushroom growing kit, don't empty the bag out and dispose of the compost - use it to grow a crop of vegies first. Even after the mushrooms stop producing the home mushroom growing kit is still a container full of weed free, well drained and fertile growing media that can produce a terrific crop of lettuce, tomatoes or some other vegetables. When you have finally finished growing the vegie crop, use the compost to top dress a garden bed. It will encourage worms, and improve both structure and nutrition in the soil below.
One word of warning - some mushroom composts can be very alkaline (a high pH) which can affect the growth of some plants. If you are only using small amounts of the compost you shouldn't have too many problems, but if you are using larger amounts then it is worthwhile checking the pH of the compost using a simple testing kit readily obtained from your local nursery or garden supplies, and adjusting the pH if necessary. Alternatively only grow plants in it that like an alkaline growing media.
MUSHROOM KITS for the Beginner.
Mushrooms can easily be grown using kits, which are available in supermarkets and nurseries. The kit consists of a growing box, spores and compost. They can also be grown in trays, raised beds and large plastic bags. The kits are kept in a cool dark place, and the first mushrooms can be ready to harvest in 2-3 weeks. Further crops occur every week or so (these are called flushes). After a month or two the flushes have usually become so poor, that the compost is discarded (added to compost heaps, used as a mulch, or dug into garden beds).
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