Instructions: The term "farming" connotes a palette of green and golden hues extending endlessly into a sea of blue sky. Unless, of course, whats being grown is a member of the fungus family.

Our footsteps echo in the empty chamber of the building that is a nursery to the 40,000 pounds of portobello mushrooms that are harvested weekly at the Arroyo Grande Mushroom Farm in Central California.

The rectangular barn stretches a city block in length. Its dimly lit corridor is wide enough to allow passage of a bulldozer. Sixteen growing rooms, eight on each side, line the stark hallway. Within each room are two columns of multilayered shelves. Millions of mushroom caps are nestled in the lengthy beds.

Various sizes of beige spheres peek through the dark, rich moss.

There is not so much as a fly on a wall or a cow pie to be seen at this farm; the mushrooms grown here dine upon a sophisticated substitute for manure. The fungal entree served at the farm is a blend of straw and grape humus. Once the little aristocrats are well-fed, they are sweetly tucked into bed with a moist layer of peat moss.

There is a stillness. The kind of quiet that is reminiscent of an early spring morning after a rain. Two women are reaching into the long, fecund beds gently plucking the portobellos from the moss. They appear to be harvesting, but what they are really doing is thinning the crop.

The name, portabella is seen regularly in markets and books alike, but the true name is portobello. A portobello mushroom is actually a very large cremini, and a cremini is a brown version of the common white button mushroom. The portobello is more distinct in flavor than the cremini, simply because it is older and the flavor has been given time to develop.

The growing time of a portobello is approximately a week, from the time the spore-laden straw is lain in these long, shelved beds until the time they are harvested for shipping. In three days a portobello can go from the size of a grape to the size of a cantaloupe.

"You know the term, things are mushrooming?" asks Art Lopez, operations manager of the farm. He is referring to the explosive growth of this innocuous-looking crop. "Things get very intense around here." he concludes, laughing.

Sixteen growing rooms, each one planted two days apart, keep employees working around the clock once harvest begins.

From preparation of the compost to
the placement of the crop into the growing room, a growing cycle averages 100 days.

The first stage in the three-month cycle begins with preparing the compost.

The straw compost is cooked at 140 F, then pasteurized at 160 F. The straw becomes a moist, black mat that is blended with grape humus, and is eventually inoculated with the spawn (mushroom seeds the size of fairy dust). The spawn are mixed with rye berries, upon which they attach themselves. The mixture of straw and spawn-drenched grain are put to bed under a moss coverlet in the growing rooms to mature.

Tiny white pinheads peep through the moss, next to cream-colored crimini, next to portobello the size of an orange. Some of the incoming mushrooms have to be sacrificed for the good of the crop. Three thinnings are followed by three harvests throughout their stay in the growing room. And then the 100-day growing cycle begins again.

Some of the mystique surrounding the mushroom is the sheer lack of evidence that heralds its arrival; seemingly, they appear from nowhere. And this is why it is labor-intensive for the harvesters once the spawn are in the growing rooms. They must be constantly alert to new growth so there will be no over-crowding of the voluminous portobello.

The cultivation of mushrooms in captivity is a tricky business. However, shopping for and preparing the enigmatic mushroom is a simple pleasure.

Crimini are bought while the cap is still closed, while the portobello is reaching its prime when its gills are revealed. Once the gills flare open, the flavor becomes much more robust and earthy.

Generally, portobellos are found in the market with the cap open. In turn, they always have more flavor then their infantile brethren. Enjoy them in a rustic sauce, intense broth or as a toothsome meal. The versatility of the portobello is endless.

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