Preparing Garden Soil


You can improve your garden soil by adding organic material or fertilizers. See pictures of famous gardens.

Garden soil needs to be the right texture and full of nutrients in order to support healthy, happy plants. You need a good mixture of sand, silt, clay, and organic material to create the perfect soil. Most gardeners will need to do some work on their soil before it is in top condition.

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If you don't have the loose, dark earth of those fabulous gardens you've seen on television and in magazines, don't despair. It can be created by improving your existing soil for fertility and good drainage. Soils can be amended with sand to make them looser and drier or with clay to make them moister and firmer. They can be given plentiful doses of organic material -- old leaves, ground-up twigs, livestock manure, and old lawn clippings, plus appropriate fertilizer. Organic matter improves and nourishes any kind of soil, which, in turn, encourages better plant growth. Some soils are naturally pretty good, but others may need significant improvement if they are to support a beautiful garden.

Your soil texture checkup has shown the percentage of sand, silt, and clay in your soil, a good starting point for improving it. But you should also have your soil tested before yo­u start adding fertilizers and amendments to it. This is in keeping with the old adage, "If it ain't broke, don't fix it." Sometimes unnecessary tampering with nutrients or soil acidity can actually create more problems than benefits.

Garden soil tests can give you a clear picture of what your soil needs to succeed, such as the acidity level and how to balance it for the benefit of your plants. In this article, you'll learn about ways to improve the quality of your soil through the use of mulch, compost (which may require you to build your own compost pile), and several different types of fertilizer. You'll also learn about the unique properties of soil used for container gardening. Keep reading to begin the process of testing your garden soil.

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Garden Soil Tests

©2007 Jupiter Images Corporation Don't add more fertilizer to your soil than the soil test says is necessary.

Soil tests tell you the nutrient levels in your garden soil, a plant version of the nutrient guides on packaged foods. They also note pH and organic content, two factors important to overall smooth sailing from the ground up. To have your soil tested, call your local Cooperative Extension Service, often listed under federal or county government in the phone book. Ask them how to get a soil-testing kit, which contains a soil-collecting bag and instructions. Follow the directions precisely for an accurate report.

The results may come as a chart full of numbers, which can be a little intimidating at first. But if you look carefully for the following, you can begin to interpret these numbers:

  • If the percentage of organic matter is under 5 percent, the garden needs extra compost.
  • Nutrients will be listed separately, possibly in parts per million. Sometimes they are also rated as available in high, medium, or low levels. If an element or two comes in on the low side, you'll want to add a fertilizer that replaces what's lacking.
  • Soil pH refers to the acidity of the soil. Ratings below 7 are acidic soils. From 6 to 7 are slightly acidic, the most fertile pH range. Above 7 is alkaline or basic soil, which can become infertile above pH 8. Excessively acidic and alkaline soils can be treated to make them more moderate and productive.

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Soil pH Levels

Garden soil tests will tell you the pH level of your garden. If a soil test indicates that your soil is very acidic, consider growing acid-loving plants, or try ground limestone to raise the pH. Limestone is nature's soil sweetener, capable of neutralizing overly acidic soils. It's best to add limestone in the fall to allow time for it to begin to dissolve and do its job. The amount of limestone you use will vary depending on the specific soil conditions. Don't dump limestone on soil randomly, because you run the risk of overdosing the soil with lime. Follow guidelines on the limestone package or on your soil test. Maintaining the new and improved pH is an ongoing project. Recheck the soil's pH every year and continue to add limestone as needed.

If, on the other hand, your soil test shows that your soil is on the alkaline side, add cottonseed meal, sulfur, pine bark, compost, or pine needles. Garden sulfur is a reliable cure when added as recommended in a soil test. It acidifies the soil slowly as microbes convert the sulfur to sulfuric acid and other compounds. Soil amendments such as compost, decaying pine bark, and ground-up pine needles gradually acidify the soil while improving its texture.

Composting is an inexpensive and organic way to add nutrients to your garden soil. Keep reading to learn how to compost.

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How to Compost

Every type of garden soil can be improved with additional organic matter, and one of the best and easiest ways to get organic matter into your soil is by adding compost. In fact, compost is simply organic matter that has already broken down sufficiently for its minerals and nutrients to be accessible to plants. You can buy compost, or you can make your own.

Organic material decays most quickly if blended with approximately equal parts of the following:

Nitrogen-rich soft and green material

  • Manure from chickens, cows, horses, rabbits, pigs, guinea pigs, and other herbivores
  • Fruit and vegetable peels
  • Grass clippings
  • Green leaves
  • Strips of turf
  • Alfalfa

Carbon-rich brown and material

  • Wood chips
  • Ground-up twigs
  • Sawdust
  • Pruning scraps
  • Autumn leaves
  • Straw

Making your own compost is beneficial for your garden, and it lets you recycle yard and kitchen waste. Keep reading to learn about starting your own compost pile.

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How to Make a Compost Pile

Yard scraps are a perfect addition to your compost pile.

Making your own compost pile is a good way to create inexpensive, nutrient-rich organic material for your garden. To begin a compost heap, dump yard scraps in a far corner of the yard. An ideal blend would be equal amounts of soft or green material (manure and fresh leaves) and brown or hard material (dead leaves and chopped twigs); see the list above. Or, if you prefer, keep the compost materials neatly contained in a wooden slat or wire-mesh bin. If you put an access door on the bottom of the bin, you can scoop out the finished compost at the bottom while the rest is still decaying.

Add compost starter or good garden soil to a new compost pile to help jump-start the decay of organic materials. Compost starter, available in garden centers or from mail-order garden catalogs, contains decay-causing microorganisms. Some brands also contain nutrients, enzymes, hormones, and other stimulants that help decomposers work as fast as possible. Special formulations can be particularly helpful for hard-to-compost material such as wood chips and sawdust or for quick decay of brown leaves.

Good garden or woodland soil, though not as high-tech or as expensive as compost starter, contains native decomposers well able to tackle a compost pile. Sprinkle it among the yard scraps as you are building the pile. You can speed up the compost-making process by chopping up leaves and twigs before putting them on the compost pile. The smaller the pieces are, the faster they will decay. Chopping can be done easily with a chipper-shredder or a mulching mower.

Use perforated PVC pipes to aerate compost piles. An ideal compost pile will reach three to four feet high, big enough to get warm from the heat of decay. High temperatures -- when a pile is warm enough to steam on a cool morning -- semisterilize the developing compost, killing disease spores, hibernating pests, and weed seeds. But for decomposers to work efficiently enough to create heat, they need plenty of air -- and not just at the surface of the pile. Aeration is traditionally provided by fluffing or turning the pile with a pitchfork, which can be hard work. But with a little advance planning and a perforated pipe, this can be avoided. Start a compost pile on a bed of branched sticks that will allow air to rise from below. Add a perforated pipe in the center, building layers of old leaves, grass clippings, and other garden leftovers around it. The air will flow through the pipe into the pile.

Making your own compost takes several months, so many gardeners find it easier to purchase bagged compost. Either way, compost is a good additive for soils low in organic materials. Added to clay soil, compost lightens the soil and improves aeration; added to sandy soil, compost improves water-holding capacity.

Adding compost is just one way to improve your garden soil. On the next page, learn about using mulch to beef up your soil.

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Improving Garden Soil with Mulch

In addition to composting, you have many options for improving the quality of your soil. Adding mulch is another good method to consider. Add a thick layer of mulch and let it rot to improve the soil of existing gardens.

Minerals, released as the mulch is degraded into nutrient soup, soak down into the soil and fertilize existing plants. Humic acid, another product of decay, clumps together small particles of clay to make a lighter, fluffier soil. For best success, remember these points:

  • Woody mulch, such as shredded bark, uses nitrogen as it decays. Apply extra nitrogen to prevent the decay process from consuming soil nitrogen that plants need for growth.
  • Don't apply fine-textured mulches, like grass clippings, in thick layers that can mat down and smother the soil.
  • Use mulch, which helps keep the soil moist, in well-drained areas that won't become soggy or turn into breeding grounds for plant-eating slugs and snails.

If a soil test reveals that your garden is missing essential nutrients, you'll want to add fertilizers to your soil. Learn all about garden fertilizer on the next page.

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Garden Fertilizer

Fertilizers for "bloomers" will help flowers and fruits grow well.

Garden soil often needs some help to achieve the right mix of nutrients. Depending on your soil test results and what you are planting, you probably will need to add packaged fertilizers to your garden soil in addition to mulch and compost.

Use packaged fertilizers according to directions. In most cases, use balanced formulations with similar numbers (5-5-5). The numbers stand for nitrogen (N), phosphorus (P), and potassium (K), in that order. Sometimes you need special formulations for special purposes. Lawn food is high in nitrogen, which is great for leaf growth, whereas "bloomer" fertilizers for flowers and fruit are proportionately lower in nitrogen and higher in phosphorus and potassium (5-10-10, for instance).

Formulations for roses, vegetables, tomatoes, holly trees, and others have special attributes that are matched to the plants. Slow or time-release fertilizers are usually in a beadlike form and give out their nutrients little by little, through many rains or waterings. They help keep plants blooming or producing all season long.

Liquid or soluble fertilizers reach the roots immediately for an instant boost but must be reapplied on a regular basis. For details on how to use fertilizers properly, read the package labels. The volume of fertilizer required may vary depending on the kind of plant being fertilized and the time of year.

Compost and bulky organic material, such as composted manure, also provide major and minor nutrients and should give you trace elements your soil needs. They improve the texture of the soil and add organisms that contribute to replenished nutrient supply, naturally. Expect to use more organic fertilizer, by volume, than synthetic chemical fertilizers because organic fertilizers contain fewer nutrients by weight, averaging from one to about six or seven percent. Contrast this with an inorganic lawn fertilizer that may contain up to 30 percent nitrogen, more than four times as much as organic fertilizer.

More is not always better when it comes to fertilizers. Lower-dose organic fertilizers are unlikely to burn plant roots or cause nutrient overdoses. Many forms release their components slowly, providing a long-term nutrient supply instead of one intense nutrient blast. Organic fertilizers may also provide a spectrum of lesser nutrients, even enzymes and hormones that can benefit growth.

What kind of fertilizer is best for your garden? Keep reading to learn about the different types of garden fertilizers.

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Garden Fertilizer Types

Granular fertilizers used for side-dressing should be used in spring and again mid-summer.

Different types of soil fertilizers serve different purposes in your garden. Here are a few fertilizer types to explore:

Side-Dressing

Granular fertilizers release nutrients more quickly than organic fertilizers. Sprinkling a handful of 5-10-5 around each plant (known as side-dressing) in spring and again mid-summer will give annuals a feeding boost that will keep them in top growing and flowering condition through the summer. Use slow-release fertilizers once in the spring.

Liquid fertilizers provide nutrients immediately. Be careful not to overdo it.

Liquid Fertilizer Solution

Liquid fertilizer is an immediate source of nutrients. The concentrated form is diluted by mixing with water according to the manufacturer's directions. Use a mild solution on new transplants to help them quickly recover from the shock. Liquid fertilizer can be applied in place of granular side-dressings.

Fish Emulsion Fertilizer

Use fish emulsion fertilizer to encourage a burst of growth from new plantings, potted flowers and vegetables, or anything that is growing a little too sluggishly for your taste. High-nitrogen fish emulsion dissolves in water and is easily absorbed and put to immediate use by the plant. For best results, follow the package directions.

When gardening in containers instead of in the ground, you're more easily able to adjust the soil to suit your plants. Keep reading to learn about preparing soil for container gardens.

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Soil for Container Gardening

Container plants rely on the soil in their pot for all of their nutrients.

Container gardening is perfect for beginning gardeners because you can control the soil (and other variables, such as light condition) more easily than you can with a traditional garden. However, you must be sure to carefully prepare your soil for container plants.

Soil texture and fertility are very important in containers; your plants have to depend on what's in the pot for their necessary moisture and nutrients. They can't send their roots out farther, looking for more. And they can't escape rotting if they are trapped in soggy conditions.

The correct soil depends on varied factors such as the type of plant and the climate and exposure of the site. Most gardeners avoid pests and diseases in their pots by using bagged products, but you can use your own compost if you really trust it.

For most plants, choose a commercial mix prepared for potted plants. If it has been formulated without additional fertilizer, mix in time-release fertilizer beads according to package directions. Or mix your own potting soil with a third each of loam, peat moss or compost, and perlite, incorporating time-release fertilizer.

Gel granules (for keeping soil moist) can also be stirred in. For plants that need especially good drainage, such as narcissi, tulips, cyclamen, and others with bulbous roots, add plenty of extra perlite in the mix, and top the pots with tiny pebbles or a quarter-inch layer of perlite.

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