Laying the groundwork for glory

So as not to scare us off, garden writers have a tendency to resort to dainty euphemisms. Take “amend the soil” or, alternately, “improve the soil.” These don’t mean “take it to confession” or “send it to finishing school.” They mean: Get out and dig. Or, if you have a lot of ground to cover, hit it with one of those urban plows called rototillers.

It isn’t just hard work. It’s backbreaking. If you haven’t done it to your lot, or a certain bed, the bad news is: Now is the time to do it, at the opening of fall planting season and before winter rain. The good news is, it is the single most important thing you will ever do for your garden and your house and, if done right, it will bear endless rewards.

You can hire people to do it. Sometimes we have to. But if you possibly can, do it yourself. Working the earth is the best way to get to know your property, whose soil profile can change completely from one end of a 150-foot-long lot to the other. You find where the builder dumped his rubble, where owls pooped out squirrel skulls, where a rock outcropping was chopped off by developers, maybe even where a stream once ran. It’s also the beginning of real gardening. The most basic thing for any garden isn’t plant choice, or the elegant turn of a garden path, or a nicely enameled bird bath, it’s soil condition.

Once digging is done, you are now ankle deep in the fundament from which everything in the garden grows -- or doesn’t. Start gardening in improved soil, and nature opens up. Suddenly we see how plants work and understand what they need, from the roots up and not just from the ground level up.

More often than not, the soil we start with will be seriously depleted. For much of the 20th century, many of us believed not in soil condition, but in better living through chemistry. Recently, a group of very unlikely people -- football coaches -- were among the first urban groundsmen to look to antique farming and gardening methods, and to insist that regimens of lawn chemicals be augmented by good old-fashioned amendments. It was a question of buoyancy. They noticed that leaving cut grass on the ground, called grass cycling, and adding manure and compost every year softened the soil and reduced the number of bone fractures. For homeowners, the same principle means that children’s falls can end with bruised egos and not broken bones.

Our soil wasn’t always hard. Back when Southern California was tribal land, then cultivated farmland, its soil didn’t need improvement. It had some of the best topsoil in the world, and geologists had more names for it than France has cheeses. Soper gravelly sandy loam. Milsholm loam. Mocho loam. Saugus loam. And so on.

But urbanization has transformed it. When builders come in, the first thing they do is cart away loose topsoil, then wet and steamroller what’s left to make it as rock-like as possible. Once they’ve laid roads and building foundations, they might bring back some of the native soil to layer around houses, but chances are they will import a thin layer of compost from a recycling yard, rake it into a thin, ephemeral layer, unroll some turf and call it a lawn.

Once a home is built, compacted soil becomes treacherous. A tiny settlement in the grade can redirect rainfall away from the curb and back into the foundation. One of the best ways to correct this is to grade and rehabilitate the topsoil, an absorbent layer that will capture water much the way a towel stops a spill flooding across a hard kitchen floor. The water then has time to percolate down to the compacted soil below.

The first step to working with the soil that builders leave behind is determining its character. It will be one of three things: sand, silt or clay, says Jim Downer, University of California cooperative extension agent for Ventura County. Foothill soils tend to be rocky variations on sand or decomposing mountain. Silt is rare. Most of L.A. soil is variants of clay.

Clay and sand present opposite problems that have the same solution: working in organic matter. Sand particles are large and loose. Water runs straight through them and nutrients are washed out from underneath the root system. Organic matter in sand will help hold water, plus provide nutrients.

Meanwhile, clay particles are tiny and fine and tend to clump together. Compacted urban clay can be so hard, bullets would ricochet off of it. Rainwater and irrigation run straight off the lot and down the drain. Once this impervious stuff finally does absorb water, it takes another eternity to dry out. When in this saturated state, there is so little oxygen that it can effectively drown plants.

When broken up, the particles stop binding with one another and reconnect with organic matter, creating large, porous particles that can then, and only then, conduct water, oxygen and nutrients to the plants. This also allows lots of beneficial bacteria and fungi to do their things, which research out of Ohio State University shows help control plant diseases.

Whether bulking up sand or fluffing up clay, there is no shame in doing it one bed at a time, even one a season. Keep in mind that urban plowing is not to be done around established shrubs and trees, but where you have removed concrete, or taken back a cheap builder’s lawn, or in a fallow bed of annuals.

The soil should be turned to a depth of six inches, or about the length of the best tool for the job -- a small-faced shovel called a “lady shovel.” Or any slender shovel, even post-hole diggers, will work.

If it is clay and too dense to penetrate with a shovel, break it up first with a pick. Wetting impenetrable ground will soften it and is fine for digging planting holes, but for amending, it isn’t smart. The soil will be too heavy and muddy to turn.

After picking out the rubble, weeds and interesting fossils, you then get to spread smelly stuff, politely known as improvements. The tilled area should be covered by two inches of rotted organic stuff, including compost, to loosen the soil and manure with nitrogen to feed it. The names on the sacks of soils sold in home improvement stores are confusing. Mushroom compost. Bark compost. Plain old compost. Topper. Orchid mix. Patio mix.

If you use a compost, match every four sacks with one of manure for nitrogen. Or select a premixed version of the two. Kellogg, one of our local formulators of rich dark stuff, eliminates confusion by calling one of its basic mixes Amend. This and other brands are sold in bags, from $3 to $4 each, or by bulk in large cartons at home improvement stores. They make a good alternative to the landscaper dumping a truckload of stuff in your driveway.

Do not buy potting soil, patio mix or any of those souped-up soils. These are fine for houseplants and their white fillers -- perlite, pumice or Styrofoam -- help lighten the weight of patio pots, but they have no place in garden soil.

Once the soil is turned, hooray, for then it’s time for more digging. You need to turn this muck back in. It should be mixed thoroughly enough that the existing soil and amendment look blended and there are no untoward clumps.

At this point, if you’re not bone-tired, you’re on steroids. Amending is such hard work that it’s tempting to bypass it and reach for fertilizers. However, you might as well rip up dollar bills and throw them at the plant. Fertilizers are wasted in poor soil. They will wash away in sand or in clay -- the soil chemistry will prevent their absorption by the plant.

The chances are good that unimproved soil is alkaline, with a pH between 7 and 8. Improving the soil with compost and manure should take it into what horticulturists call “the cherry zone” of slightly acidic, nearly neutral 6.5 to 6.8 soil, where most nutrients are available. High pH, or alkaline soil, can restrict iron uptake, resulting in the common garden problem of yellowing citrus trees. But until you have improved your soil, do not become bogged down in questions of acidity. Chances are, the pH will drop once you’re done. If it doesn’t, then reach for fertilizer.

Most of us still picture soil turning as a yearly ritual. But there is an argument developing among soil scientists and the organic movement in favor of no-till agriculture. This views plowing as damaging to good earth.

But no-till applies to healthy soil. Most urban gardeners, particularly in Los Angeles, need to till those six inches to create an interface between new organic matter and existing compacted foundation earth. Only after that first amendment can gardeners then turn to yearly, or even biannual, top-spreadings of manure and compost. You won’t need to dig these in, the earthworms will come get them for you. You’ll know they’re there without turning the soil, because all sorts of grateful birds will appear.

By improving soil, we are just emulating what happens naturally on a forest floor. Every year, nature showers down a new layer of good organic stuff that slowly breaks down. It becomes buoyant and dazzlingly fertile.

To make sure that all your hard work doesn’t blow away with the Santa Anas or get tracked into the house, it is best to cover the soil with top-mulch after planting. This is also key for water retention. Wood bark is decorative, but leaves and grass do the same job. Aim for three inches on top of the amended six inches.

Hell, you’ve worked hard enough. Settle for two.

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Compost made from recycled grass clippings and garden waste is given away by Los Angeles County at four sites: Central Los Angeles (2649 E. Washington Blvd., open 9 a.m. to 5 p.m.); San Pedro (1400 Gaffey St., at the entrance to the Harbor District Refuse Yard, open 24 hours); Northridge (at Wilbur Avenue and Parthenia Street, open 9 a.m. to 5 p.m.); and Lakeview Terrace (11950 Lopez Canyon Road, open 7 a.m. to dusk).

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Digging deeper into soil care

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It is a rare gardening book that dwells on earth as more than a delivery system for fertilizer. However, Rodale’s Illustrated Encyclopedia of Organic Gardening (Dorling Kindersley, 2003) dedicates a full chapter to soil and soil care. These 30 pages alone are worth the $40 price tag. They explain the formation of soil and the importance of organic matter, then identify beneficial bacteria and fungi and common soil-dwelling insects. There is just enough soil chemistry and a clear guide to start home composting.

-- Emily Green