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Soil and Soil Amendments

There is nothing more basic to your garden than the soils  and fertilizers that you decide to use.  There is a lot to know about soil, and depending on the type of gardening you do and your level of gardening expertise, you may want to check out some of the external links for more extensive information. Read on for a quick introduction to everything you need to know about soil for your home and garden use. Happy planting! 

The Dirt on Your Dirt

You might be thinking to yourself, "I've got a whole yard full of dirt; why should I buy more dirt when I get it for free?" You're right -- there's plenty of good dirt, and if you're lucky you might have a great yard full of perfect dark-brown loam. Your vegetables win prizes at county fairs, your flowers are big and fragrant, and your shrubs have filled out nicely every year.

If you're like the other 99% of the gardening population, however, your yard could probably use a little help. Maybe you live in an apartment and want to start a garden on your balcony. You might want to plant annuals in pots,  create a raised bed for your veggies, or dozens of other projects that require more dirt than your yard can supply. Whatever the reason, sooner or later almost all gardeners will need to buy more dirt. Fortunately for you, there are many kins of planting media on the market today, from generalized all-purpose planting mix to plant-specific soils. You can buy big bags to supplement your veggie garden  or just enough to expand your prized orchid  collection. In addition, you can now get organic potting soil  to use for organic flower, vegetable or herb gardens, or just to "green" your garden even further. 

What is Soil?

Soil is a complicated mixture of organic and inorganic matter. The inorganic portion is mostly weathered rock, in the form of gravel, sand, silt, or clay, as well as air and water. The organic part is composed of both living and decaying plant and animal matter. In addition, a healthy soil has thriving populations of microorganisms. Fertile soils usually have a humus component, which helps stabilize the soil. If you're interested in reading a lot about soil (and there is quite a lot to read) check out this Wikipedia article about soil and this one on humus.

Buying Soil

There are a number of ready-made soil mixtures available. Most of the time they are labeled with their uses, but it isn't always easy to know at first glance what you need.

  • "All-Inclusive" Mix  -- all-purpose soil that you can use in containers or beds.
  • Potting Mix  -- for potting/repotting, of course. Contains lots of organic matter as well as particles to improve drainage and water retention, which can be problematic in a pot.
  • Professional Grower's Mix  -- good for starting seeds, but it dries out easily. You'll want to transfer them to proper potting soil when they're old enough.
  • Planting Mix  -- contains a lot of compost and sand; good for outdoor plants, but don't use it for your houseplants.
  • Potting Soil  -- think of this as "Potting Mix Extra Chunky" -- may contain large pieces of organic matter.
  • Plant-Specific Mixes  -- specifically formulated for certain kinds of plants, such as vegetables or roses, or for lawns. These mixes often contain a specific blend of nutrients formulated for that group of plants.

Lowe's advises buying prepackaged garden soils to avoid contamination from insect eggs and larvae, fungal spores, seeds from weeds, and other undesirable traits in your soil.

Soil Amendments

Different soils have different physical properties. Clay and silt hold moisture and nutrients well, but they don't drain well and can be hard for plants to penetrate. Sandy soils drain well, but they don't hold nutrients and can quickly become depleted.

To fix a problem with soil texture, you should add an amendment. Often, compost is the answer -- it solves many problems in different kinds of soils. The best choice, of course, if your own home-made compost. If you haven't got a compost pile yet, many of these choices will help you in the meantime. (But you should really get a compost bin. )

  • Compost -- many gardening supply stores will sell you fresh compost. 
  • Composted manure -- composting manure  helps release the nutrients contained in the raw manure. It's also less... fragrant.
  • Humus -- organic matter in an advanced state of decay -- very dark and full of nutrients. (Not the chickpea spread, that's hummus.)
  • Sphagnum peat moss  -- plant matter that can hold a lot of water -- good for amending sandy soils, but may be problematic because peat bogs are becoming endangered habitat. You can also look for coconut husk  based amendments. 
  • Lowe's has some excellent, easy-to-ready articles on soil and improving your soil.

Soil can also be amended to adjust its pH. The pH of the soil is how acidic or basic it is and can easily be tested with a small soil test kit.  Most plants prefer a neutral or close to neutral pH of about 6.5-7.5. A pH of 7 is perfectly neutral. A lower number indicates a more acidic soil, and a higher number indicates a more basic soil. To lower pH, add sulfur  to the soil. To raise the pH, add lime  to the soil.

Mulch

For more information, read the guide to buying mulch.

Fertilizer

For more information, read the guide to buying fertilizer.

Organic, Vegan, Biodynamic...

Organic vs. Inorganic

Organic -- people keep using that word. Whatever you think organic means, it also means something else. There are three meanings for the term:

  • From a strict chemistry perspective, organic means any compound containing carbon. Urea created in a lab is organic; naturally-occurring phosphate is not organic.
  • Another definition is that organic means anything derived from a plant or animal. Thus, synthetic urea would not be organic, naturally-occurring phosphate is not organic, but manure is organic.
  • The broadest definition, and the one used for organic farming and gardening, is that anything existing naturally, whether animal, vegetable, or mineral, is organic. By this definition, synthetic urea is not organic, but naturally-occurring phosphate and manure are.

Other Potting Necessities

External Links

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