Gardening for Geeks. Christy Wilhelmi
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In-Ground Planting
While unconstructed, or berm, beds are essentially the same as in-ground planting, the difference is height. An in-ground garden bed is made by loosening the existing soil of the desired planting area and working (digging) compost into the top 4 to 6 inches (10 to 15 cm). If you have existing soil that tends toward sand or loam, this is a fine choice. Those with clay soil will find it difficult to cultivate a garden this way without adding copious amounts of compost. In fact, clay soil is the reason raised beds were invented in the first place! Because clay soil doesn’t drain well and takes longer to thaw after winter, use this method only if you have sandy, well-draining soil.
Be sure to test your soil before planting in the area. Most university agriculture departments offer basic soil tests, and some will test your soil for heavy metals. Do you know the history of the land you plan to cultivate? With all of these good intentions for healthier living, it would be a shame to inadvertently poison yourself by growing food in soil contaminated with heavy metals, so be safe and get that soil tested. We’ll talk more about soil nutrients and heavy metals in Chapter 3.
Conditioning an in-ground planter takes about as much sweat and elbow grease as an unconstructed bed. Many first-time gardeners like to try this method before committing to a formalized garden layout. It doesn’t require a lot of planning, just a lot of compost. Work the compost down into the top 4 to 6 inches (10 to 15 cm) of soil. The deeper you loosen and amend the soil, the better your crops will grow. You can add decorative elements, like stone or brick borders, and put stepping stones throughout the planter to avoid compacting the soil.
No matter what type of raised bed you decide to use, just know that good planning pays off. Your garden will reward you with a bountiful harvest if you put some time and energy into the overall design and structure. Build your beds once and enjoy them for years to come.
Chapter 3
All about Soil
Soil is the foundation of every great garden. Without healthy soil, plants may grow, but they won’t thrive. Plants take up all of their nutrients from the soil (OK…plus the energy they get from the sun), and they need space to spread their roots, so it’s important to create and maintain a healthy soil environment for your crops. What makes up a healthy soil environment? A lot of things. Let’s take a look at the cast of characters.
Nutrients
Soil contains a vast array of elements and minerals that play an important role in a plant’s life. The “Big Three” are nitrogen (N), phosphorus (P), and potassium (K). Nitrogen is responsible for green, leafy growth. It’s what makes your tomato plants grow big, green, and bushy. Phosphorus helps those tomato plants develop strong roots and, more importantly, make flowers that eventually turn into fruits (yes, a tomato is technically a fruit). Potassium, sometimes referred to as potash, helps support a plant’s overall vigor as well as fruit development and disease resistance. Together, these three ingredients lend themselves to raising happy, productive vegetables.
Crops grow abundantly in healthy soil.
The Big Three do not work alone, however. They have a supporting cast, an ensemble of minor characters that help make their work easier. Trace minerals, including calcium, sulfur, iron, magnesium, manganese, and boron, all have jobs to do. They help facilitate nutrient uptake to plants and perform specialized tasks such as forming proteins, catalyzing chlorophyll, and dividing cells. The Big Three may be the stars, but they can’t perform at their best without the support of trace minerals.
pH
Your soil will likely be acidic or alkaline, and soil pH measures the degree of that acidity or alkalinity. On the acid side of the soil spectrum (about 4.5), plants such as camellias, blueberries, azaleas, and hydrangeas thrive. In fact, the more acidic your soil is, the bluer your hydrangeas. On the alkaline side (about 8.0), artichokes, mint, and asparagus do well. Most vegetables like to grow in an environment that borders a neutral pH, which is 7.0, with many varieties flourishing in a range between 5.5 and 7.5.
Changing the pH of your soil is not like changing the pH of your swimming pool. In a pool or spa, you just add a few chemicals, and—poof!—the pH is different. It doesn’t work that way with soil. It can take years to alter the pH of your garden soil, so the best approach is to find plants that do well in your existing soil conditions. That said, we’ll cover ways to amend your soil to increase acidity or alkalinity later in this chapter.
Soil Texture
It’s time for a very important question: When you stick a shovel in the ground, does it slide right in, or does it barely penetrate the soil? Your soil’s texture is going to determine how hard you will have to work to get your garden ready for planting, or at least which type of planter bed you will use. With texture, there is also a spectrum, just as with the acid/alkaline spectrum, and your soil texture will fall somewhere along the spectrum between clay, silt, and sand. There are pros and cons for each.
Microscopically, clay soil is made up of small particles, with very little airflow between them. Clay soil tends to drain poorly and is difficult to dig. In spring, in places where the ground freezes over, clay soil takes much longer to thaw, drain, and become ready to work than sandy soil. Many gardeners avoid the whole process by building raised beds (turn back to Chapter 2 if you decide you want to do that). The benefit of clay soil is that it holds water and nutrients very well. Gardeners don’t need to add fertilizer as often, nor do they need to water as much, with clay soil, so it isn’t all bad.
Sandy soil, on the other hand, is very loosely put together. Unlike clay soil, which forms into hard clods that are difficult to break up, sandy soil runs through your fingers and doesn’t hold together if you try to form a clump. Under a microscope, you can see that it is made up of large particles. It’s fantastically easy to dig, and it drains very well. The problem is that it drains too well. As a result, sandy soil loses moisture quickly—with all that fantastic drainage, away flows all of your carefully applied nutrients as well. Gardeners with sandy soil have to water more frequently and generally have to stay on top of adding amendments.
Silty soil behaves like a combination of clay and sand. The particles are larger than clay but nowhere near as large as sand. These particles characteristically feel silky, smooth like flour, or some even say greasy. Silty soil has a tendency to become compacted like clay, making drainage and digging difficult. Silt and sand are both made up of weathered rock particles, so they both respond to gravity in the same way—the particles will settle quickly in a water solution.
THE Soil Food Web
In addition to soil nutrients and micronutrients, there is an entire world (or “underworld,” in this case) of insects and microbial life forms in your soil that make the plant world go ’round. It’s called the soil food web, and the fungi, bacteria, protozoa, earthworms, and nematodes all have a purpose—a job to do. They are the stagehands who make the show run flawlessly.
Dr. Elaine Ingham, a soil microbiologist and president of Soil Foodweb, Inc. (soilfoodweb.com), first wrote about and coined the term “soil food web” during her research on soil microbiology in the 1980s and ’90s. Jeff Lowenfels and Wayne Lewis, while tipping their hats to Dr. Ingham, uncover this world in their book, Teaming with Microbes. They deftly explain how plants not only take up nutrients but also “produce chemicals they excrete through their roots.” The excretions or “exudates” are then consumed by fungi and bacteria, which in turn are consumed by protozoa and nematodes, which then excrete waste that is taken back up by the plant as food. How convenient!
Don’t forget the host of arthropods and insects, which burrow and aerate the soil, living and completing their