How to Prepare Garden Soil for Planting
The biggest mistake beginning gardeners make is using lousy or too-thin soil. Before planting anything in your yard, prepare your garden beds by digging to loosen the soil and adding organic material! This prep work can save you untold disappointment and, perhaps more than any other factor, assure a bountiful and delicious harvest.
If you're working with a brand-new garden (or one that fell fallow and you're bringing it back to life), you can stake it and get it ready the autumn before you plan to plant. This act gives the soil and the amendments you've added time to settle and meld. It also means you have less work to do next spring.
If a fall start isn't possible or practical, go ahead and prepare the ground in spring — but don't start too early. If the ground is still semi-frozen or soggy, digging in the soil can compact it and harm its structure. How do you tell whether it's ready to be worked in? Grab a handful and squeeze — it should fall apart, not form a mud ball.
Follow these steps when preparing your soil:
Dig deep.
Most plants are content with 6 to 8 inches of good ground for their roots to grow in.
If you're planning to grow substantial root crops (potatoes, say, or carrots), go deeper still — up to a foot or more (yes, you can use a technique called hilling, where you mound up good soil around crops like potatoes, but this method doesn't excuse your making a shallow vegetable garden).
Fill 'er up.
Add lots and lots of organic matter! Try using compost, dehydrated cow manure, shredded leaves, well-rotted horse manure (call nearby stables), or a mixture. If your yard happens to be blessed with fertile soil, adding organic matter is less crucial, but most soils can stand the improvement. Mix it with the native soil, 50-50, or even more liberally.
Maybe your area's soil is notoriously acidic, or very sandy, or quite obviously lousy for plant growth. The good news is that organic matter can be like a magic bullet in that it helps improve whatever you add it to. You have to replenish the organic matter at the start of every growing season or maybe even more often. (If the soil stubbornly resists improvement, resort to setting raised beds atop it and filling these bottomless boxes with excellent, organically rich soil.)

Gardening Glossary
annuals
Plants that complete their entire life cycle within one growing season. The plant germinates from seed, grows and blooms, and then produces seed and dies.

Gardening Glossary
biennials
A plant that take two growing seasons to complete its life cycle. It germinates and grows leaves and stems in the first year; produces flowers and fruit (seed) in the second, and then dies.

Gardening Glossary
bolt
When a plant flowers or produces seed prematurely.

Gardening Glossary
cold frame
A wooden or concrete block box in which you can grow plants or hold dormant during the cold winter months.

Gardening Glossary
cole crops
A family of vegetables, including broccoli, cabbage, cauliflower, kale, and Brussels sprouts. They thrive in cooler weather.

Gardening Glossary
complete fertilizer
Any fertilizer that contains all three of the primary nutrients, N-P-K (nitrogen, phosphorus, potassium). Phrase is based on regulations governing the fertilizer industry. Does not mean that the fertilizer literally contains everything a plant needs to thrive.

Gardening Glossary
deadheading
The practice of pinching or cutting off spent flowers

Gardening Glossary
evaporative-pad humidifier
A humidifier in which fans blow across a moisture-laden pad that sits in a reservoir of water.

Gardening Glossary
harden off
The process of acclimating plants grown indoors gradually to the brighter light and cooler temperatures of the outside world.

Gardening Glossary
hardiness
The ability of a plant to survive is called its hardiness.

Gardening Glossary
humus
A stable end product of organic-matter decomposition that's believed to increase microbial activity in soil, improve soil structure, and enhance the root development of plants.

Gardening Glossary
Bacillus thuringiensis Bt
An effective bacteria that attacks only the larvae of caterpillar family insects. It is safe to other insects, animals, and humans.

Gardening Glossary
macronutrients
Mineral nutrients that plants need in the largest quantities: nitrogen, phosphorus, potassium, calcium, magnesium, and sulfur.

Gardening Glossary
mulch
Organic or inorganic material placed over the surface of soil, usually directly over the root zone of growing plants. Used to conserve moisture, kill weed seedlings, modify soil temperature, provide attractive covering to garden beds.

Gardening Glossary
organic matter
Once-living stuff like compost, sawdust, animal manure, ground bark, grass clippings, and leaf mold (composted tree leaves). Used to enrich soil and improve soil texture.

Gardening Glossary
perennials
Any plant with a life cycle of three or more years. Herbaceous (non-woody) perennials include flowering plants and herbs, mainly. Woody perennials include trees and shrubs. Longevity depends on the plant and growing conditions.

Gardening Glossary
pH
The measure of soil's acidity. Soil with low pH means it's too acidic; soil with high pH means it's alkaline. Most plants grow best in soil with a pH value between 6.5 and 7.2. Neutral soils measure 7.

Gardening Glossary
photosynthesis
The process through which plants take nutrients from the air and from the water in the soil to produce sugars that fuels the plant's growth.

Gardening Glossary
primary nutrients
Nitrogen, phosphorous, and potassium are the three nutrients plants need in the largest quantities.

Gardening Glossary
root crops
Plants with edible underground roots such as onions, carrots, beets, potatoes, turnips. Most root crops are cold-weather crops.

Gardening Glossary
self-blanching
A type of cauliflower with leaves that naturally curl over the head and exclude light. Requires cool temperatures for leaves to curl effectively.

Gardening Glossary
sets
Small onion bulbs, about 1/2-inch wide, that were started from seed the previous year. Grow onion sets with the pointy end up.

Gardening Glossary
side-dressing
The act of adding a small amount of fertilizer around or "on the side" of plants after they're growing.

Gardening Glossary
succession planting
Planting small, 2-to-4-foot patches of plants every two weeks throughout the growing season so that you can harvest a crop over an extended period of time.

Gardening Glossary
thinning
The act of cutting the least robust seedlings in your garden to give the healthier plants more room to grow.

Gardening Glossary
vining crops
Crops that grow on vines, such as cucumbers, melons, pumpkins, and winter squash. They usually require support (staking, trellising, etc.) to keep them off the ground.