Shiitakes: Are they easier to grow than to spell?

I first heard about growing shiitake mushrooms from a friend who is always looking for ways to eke out a living off the land.

He explained that hardwood logs can be inoculated with shiitake spawn, and that they will produce mushrooms on and off for four to five years.

Since these mushrooms are expensive at the grocery store - where they are favored by consumers for Asian cooking - it seemed like something worth trying.

So I did.

And although I have decided that raising mushrooms is not going to be my ticket to riches, it is easy - and enjoyable.

Kits are available to grow shiitake, oyster, and other varieties of mushrooms. They include a 5-pound block of inoculated sawdust that is placed in a large flowerpot and covered with moist peat moss or sawdust.

When the mushrooms begin to appear, the pot is covered with a plastic humidity tent, which is provided, and misted several times daily. This method will produce two to three flushes of mushrooms over a period of about three months.

But I decided to take the do-it-yourself approach. I found after doing some research, I needed some 4- to 6-inch-diameter hardwood logs cut in 3- to 4-foot lengths.

Oak will yield the best results over time, but poplar produces mushrooms a little more quickly. Chestnut, ironwood, and most hardwoods are good, but fruit trees, walnut, elm, red maple, and conifers aren't.

Logs cut in winter, when the sap is down, are best, as they will keep their bark the longest. Never use dead or fallen trees, and avoid those with badly damaged bark, as logs will remain productive only as long as they're in good shape.

Order spawn plugs from a mushroom dealer (see sidebar). These are 5/16-inch-diameter plugs of hardwood that harbor the shiitake fungus.

Get a sharp 5/16-inch drill bit to make holes 1-1/4 inches deep in the logs. A "twist bit" better than a spade or paddle bit for this process. For a 4-inch-diameter log, about 50 wooden spawn plugs were used. They cost $3.

I started at one end and drilled holes every 6 inches in a straight line to the other end. Then I drilled a new row about 2 inches from the first, staggering the holes so that they didn't line up with the first row. I continued around the log.

Some growers leave eight inches between holes and 3 inches between rows. But I wanted a larger harvest.

Next, I inserted the spawn plugs into the just-drilled holes, tapping them in with a hammer.

Finally, I sealed the plugs - to protect them from contamination - with hot food-grade wax that I had ordered at the same time I ordered the shiitake spore plugs.

I bought a used electric frying pan for less than $10, set it at 300 degrees F., and it kept the wax just the right consistency. I applied it with an inexpensive foam paintbrush.

The process sounds more time-consuming than it is: Two people working together can inoculate three or four logs in an hour.

If you follow several common-sense rules, you can inoculate logs almost any time of the year except the dead of winter in northern climates:

* Don't expose the spawn plugs to extremes of hot or cold.

* Work in the shade, as spawn is sensitive to ultraviolet radiation.

* Work in a basement or garage if it is cold and windy.

Store the logs outdoors in the shade, preferably out of the wind so they stay moist. But they should not be left in contact with the earth, which will cause rotting.

Put a couple of ordinary logs on the ground, and then stack your inoculated logs on top of them, two per layer. Some people prefer to place pieces of wood beneath the logs and lean them against trees instead.

Would it be possible for your logs to produce wild, poisonous mushrooms instead of shiitakes? There are several reasons this isn't likely to happen.

Hardwood logs that have been inoculated with commercially prepared shiitake spawn almost never grow other types of mushrooms. Most poisonous mushrooms grow in the soil, and the two common poisonous ones that will grow on wood look nothing like the shiitake.

But if in doubt, go to the grocery store and buy a couple of shiitakes to bring home for comparison with the ones you've grown.

When can you expect to harvest your first crop? In my experience, shiitakes appear mysteriously when they are ready and not until. The literature says they will appear "six months to a year after inoculation."

While you're waiting, you should spray or soak the logs during periods of prolonged drought to keep them from drying out.

I have harvested shiitakes in spring and fall. Sometimes all the logs will bear profusely; other times only a few mushrooms will appear. Each log should produce 2-1/2 to 4 pounds of shiitakes over its useful life, but this varies considerably.

It's a bit like fishing: You never know what you are going to catch, nor when, but it's always a treat.

Shiitake sources

Expect to pay about $9 for 150 spawn plugs, which is enough for three or four logs.

Mushroom Harvest PO Box 5727, Athens, OH 45701 Contact George Vaughan, the owner, by e-mail at mushroom@frognet.net, or by phone at (740) 448-6105.

Hardscrabble Enterprises Inc. PO Box 1124, Franklin, WV 26807. Contact owner Paul Goland by e-mail at hardscrabble@mountain.net or by phone at (304) 358-2921.

(c) Copyright 2001. The Christian Science Publishing Society