Garden Soil Tips

By: C. Colston Burrell

Children who are scolded for running into the house in dirty shoes may come to believe dirt is a bad thing. But just the opposite is true as long as dirt remains outdoors where it belongs.

Choosing plants that thrive in your soil and your climate will help ensure a healthy garden.
©2007 Publications International, Ltd.
Choosing plants that thrive in
your soil
and your climate
 will help ensure a healthy
 garden. See more
pictures of garden ideas.

In the garden, dirt is transformed into soil, a complex and beautiful (at least to experienced gardeners) blend of animal, vegetable, and mineral material. Good soil is the first step to a great garden.

The loose, dark earth of fabulous gardens seen on television and in magazines doesn't usually just happen. It is created by gardeners improving their native soils. 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, rotted livestock manure, and old lawn clippings. Organic matter improves and nourishes any kind of soil which, in turn, encourages better plant growth.

Probably the best way to get the most out of your soil, however, is to select plants that will thrive in your soil type and your environment. The following tips will help you choose native plants.

  • Use plants adapted to the conditions right outside your door. When plants prefer your native soil and climate, no matter how difficult these conditions may be, they are likely to grow beautifully with little effort. Native plants -- shade trees, shrubs, or flowers that arise in the nearby countryside -- are good options. Or, try less common plants from faraway places with conditions similar to your own.

  • To identify suitable plants, begin by identifying your garden conditions. Have your soil tested or do your own tests to determine if you have a light and sandy soil, a moderate and productive soil, or a heavy clay soil. Watch the site to see how sunny it is, and select plants that need full sun, partial sun, or shade, accordingly.

  • Find your location on the United States Department of Agriculture hardiness zone map, which measures winter coldness. Make a note of the light levels, soil conditions, and climatic zone information you've found. Check through nursery catalogues and gardening books to find plants that thrive in every one of the elements particular to your yard. Use these plants as a shopping list for all of your future gardening projects. A little extra legwork in the beginning makes gardening much easier over the coming years.

It's hard to make the right plant choices if you're not sure what type of garden soil you're dealing with. Learn about testing your soil on the next page.

Read Your Weeds
Look for the tales weeds have to tell as they grow in your garden. Weeds are opportunists, taking advantage of any vacant soil to make their home. (Just think of how well this strategy has benefited the dandelion, a native of Eurasia that has swept through America.) Although they seem to grow everywhere, dandelions prefer fertile, often heavy soil. Likewise, other weeds favor certain kinds of soil.

For instance, acidic soil can encourage the growth of crabgrass, plantains, sheep sorrel, and horsetails. Alkaline soil (also called sweet or basic soil) is favored by chamomile and goosefoot. Fertile near-neutral soils can provide a nurturing environment for redroot pigweed, chickweed, dandelions, and wild mustard.

Even if you can't tell one weed from the other, you can find out important information by looking at them closely. If a vacant garden area has few weeds taking advantage of the opening, the soil is likely to need plenty of work.

If they are growing, but only sparsely, and have short, stunted stems and discolored leaves, the area may have a nutrient deficiency, and a soil test is in order.

If, in newly tilled soil, weeds sprout up quickly in certain areas and more slowly in others, the weedy areas are likely to be moister and better for seed germination.

Want more gardening tips? Try:

  • Gardening Tips: Learn helpful hints for all of your gardening needs.
  • Annuals: Plant these beauties in your garden.
  • Perennials: Choose great plants that will return year after year.
  • Gardening: Discover how to garden.


Test Your Soil

Before you start adding fertilizers and amendments to your garden soil, you need to determine what type of soil you have. This follows the old advice, "If it ain't broke, don't fix it." Sometimes unnecessary tampering with nutrients or soil acidity can actually create more problems than benefits.

Soil tests tell you the nutrient levels in your 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. The following tips will help you test your soil.

  • 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 accurate results. 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 some 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.
  • Add only the nutrients your soil test says are necessary. More is not always better when it comes to plant nutrients. Don't feel compelled to add a little bit more of a fertilizer that promises great results. Too much of any one nutrient can actually produce toxic results, akin to diseases or worse. Buy only what's required and save the rest of your money for a better use, like more plants.

    Check your soil's texture with a simple test you can do at home.
    ©2007 Publications International, Ltd.
    Check your soil's texture with
    a simple test you can do at home.

  • Check the texture of your soil in a jar filled with water. This test is simple to do at home and provides important information about your soil. Gather up some soil from the garden, choosing a sampling of soil from near the surface and down to a depth of 8 inches. Let it dry, pulverize it into fine granules, and mix well. Put a 1-inch layer (a little over a cup) in a quart glass jar with 1/4 teaspoon of powdered dishwasher detergent. (Dishwasher detergent won't foam up.) Add enough water to fill the jar two-thirds full. Shake the jar for a minute, turning it upside down as needed to get all the soil off the bottom, then put the jar on a counter where it can sit undisturbed.

    One minute later, mark the level of settled particles on the jar with a crayon or wax pencil. This is sand. Set an alarm for 4 hours, and when it goes off, mark the next level, which is the amount of silt that has settled out. Over the next day or two, the clay will slowly settle out and allow you to take the final measurement. These measurements show the relative percentages of sand, silt, and clay, or the texture of your soil.

    Soil that has a high percentage of sand (70 percent or more) tends to be well aerated, ready to plant earlier in spring. But it also tends to need more frequent watering and fertilization than heavier soils.Soil that has 35 percent or more clay retains more moisture, so it takes longer to dry in spring and may need less watering in summer. It can be richer and more likely to produce lush growth with just the addition of compost and, occasionally, a little fertilizer. The compost is important. It helps break up clay so the soil won't be too thick and poorly aerated.Soil that has more equal percentages of sand, silt, and clay can have intermediate characteristics and is generally well suited for good gardening.
  • Test your soil's drainage by digging a hole, filling it with water, and watching how quickly the water disappears. All the soil tests in the world won't do a better job than this simple project. It tells you how quickly moisture moves through the soil and whether the soil is likely to be excessively dry or very soggy -- neither of which is ideal.

    When it hasn't rained for a week or more and the soil is dry, dig several holes that are 1 foot deep and 2 feet wide. Fill them to the top with water and keep track of how long it takes for the holes to empty. Compare your findings to the following scale:
    • 1 to 12 minutes: The soil is sharply drained and likely to be dry.
    • 12 to 30 minutes: The soil has ideal drainage.
    • 30 minutes to 4 hours: Drainage is slow but adequate for plants that thrive in moist soil.
    • Over 4 hours: Drainage is poor and needs help.

Now that you've determined your soil type, find out more about making changes to create the best soil possible for your environment on the next page.

Want more gardening tips? Try:

  • Gardening Tips: Learn helpful hints for all of your gardening needs.
  • Annuals: Plant these beauties in your garden.
  • Perennials: Choose great plants that will return year after year.
  • Gardening: Discover how to garden.


Amend Your Soil

Some soils are sandy; others have a high percentage of clay. Some soil drains well, while other types stay soggy for too long. The good news is most soil can be improved upon to help you create a luscious garden. The tips that follow will help you make the right changes to your soil.

  • Use ground limestone to raise the pH of acidic soils. 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. Simple home test kits, or a professional test, can be used to determine the soil's pH. If you dump limestone on soil randomly, you run the risk of overdosing the soil with lime. Follow guidelines on the limestone package or on a 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.To lower the alkalinity and increase the fertility of limestone and other soils with very high pH, 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.
  • Test your soil by feel before and after the soil is amended to judge the extent of the change. Take a small handful of lightly moist soil from several inches below the soil surface. Squeeze it into a ball in your hand and watch the results when you open your fingers. Sandy soils, which can have a scratchy feel, will fall apart. To enrich a sandy soil, apply a several-inch layer of compost and even an inch or two of clay, then try again. When the soil is improved, the ball will cling together better.

  • Clay soils, which have a slick feel, will form a tight ball that's not easily broken up. To lighten clay soil, add extra compost and coarse sand. When the soil is light enough, the ball will break up with a tap of a finger.

No matter what type of soil you have, you can continue to improve it by regularly adding organic matter. Find out more in the next section.

Sources of Specific Nutrients
Many of these fertilizers are available processed and packaged. You don't have to harvest your own in order to add them to your soil.
  • Nitrogen: livestock manure (composted), bat guano, chicken manure, fish emulsion, blood meal, kelp meal, cottonseed meal
  • Phosphorus: bonemeal, rock phosphate, super phosphate
  • Potassium: granite meal, sulfate of potash, greensand, wood ashes, seabird guano, shrimp shell meal
  • Calcium: bonemeal, limestone, eggshells, wood ashes, oyster shells, chelated calcium
  • Boron: manure, borax, chelated boron
  • Copper: chelated copper
  • Magnesium: Epsom salts, dolomitic limestone, chelated magnesium
  • Sulfur: sulfur, solubor, iron sulfate, zinc sulfate
  • Zinc: zinc sulfate, chelated zinc Iron: chelated iron, iron sulfate

Want more gardening tips? Try:

  • Gardening Tips: Learn helpful hints for all of your gardening needs.
  • Annuals: Plant these beauties in your garden.
  • Perennials: Choose great plants that will return year after year.
  • Gardening: Discover how to garden.


Add Nutrients to Your Soil

Basically all types of soil will benefit from the addition of organic matter. Check out the following tips to learn about adding nutrients to improve your soil and ultimately encouraging better plant growth.

  • 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.

      Add more soil or organic material to keep shrub or tree roots under cover.
      ©2007 Publications International, Ltd.
      Add more soil or organic material
      to keep shrub or tree roots under cover.

  • Get local compost from your city or town hall service department. Made from leaves and grass clippings collected as a public service, the compost may be free or at least reasonably priced for local residents. To find other large-scale composters, check with the nearest Cooperative Extension Service; they are up-to-date on these matters. Or try landscapers and nurseries, which may compost fall leaves or stable leftovers for their customers, and bulk soil dealers, who may sell straight compost or premium topsoil blended with compost. Don't give up. Yard scraps are discouraged or banned in many American landfills, so someone near you is composting them.

  • Plan ahead for bulky organic soil amendments -- compost, manures, and leaves -- that may be added by the wheelbarrow-load to improve the soil. This will raise the soil level, at least temporarily. As the organic matter decays, the soil level will lower.

  • If soils rich in organic matter drop to expose the top of a newly planted shrub or tree roots, add more soil or organic matter to keep the roots under cover.

  • If your garden is beside a house or fence, keep the soil level low enough so it won't come in contact with wooden siding or fencing that isn't rot resistant.

  • When planting around existing trees, shrubs, and perennial flowers, avoid covering the crown -- where stems emerge from the ground -- with organic material. This helps prevent disease problems.

Where your garden is located and how often you till your soil can also affect its quality. Learn how garden maintenance can improve your soil on the next page.

Sources of Organic Matter
Valuable organic matter comes in all shapes and sizes. Here are some of the most common:
  • Compost
  • Livestock manure
  • Straw Grass clippings
  • Salt hay
  • Shredded bark
  • Bark chunks
  • Shredded leaves
  • Seedless weeds
  • Peat moss
  • Kitchen vegetable scraps
  • Mushroom compost
  • Agricultural remains such as peanut hulls or ground corn cobs

Want more gardening tips? Try:

  • Gardening Tips: Learn helpful hints for all of your gardening needs.
  • Annuals: Plant these beauties in your garden.
  • Perennials: Choose great plants that will return year after year.
  • Gardening: Discover how to garden.


Maintain Your Garden

The location of your garden, how you till your soil, and many other factors can have a dramatic impact on your soil. These tips should help you tend to your soil the right way.

  • Don't walk on wet soils, especially clay soils. The footprints you leave are evidence of compression -- packing the soil particles tightly and squeezing out vital oxygen. This is not a desirable quality in a garden. Put walkways or stepping stones in the garden for easy access and to keep your shoes clean and dry. When planting, cover the soil with a board to kneel or stand on.

  • Till or spade a thick layer of compost into lightly moist (never wet) soil to bring it to life before planting a new garden. The going may be rough at first if you are starting with hard, compacted soil. Use a rototiller and tough it out. Go over the area, removing weed roots and other underground vegetation as you go. Then go over it again crosswise, until you break up the soil into reasonably small pieces.

  • Your well-tilled soil, like screened topsoil, may look great at first, but silt or clay soils are likely to get stiff, crusty, and hard after a few heavy downpours. The best way to keep soil loose and light is to add organic matter.

    Add a 4- to 6-inch-deep layer of compost to the soil and work it down until it's 10 to 12 inches deep. The soil will become darker, moister, and spongier -- a dramatic conversion right before your eyes. As long as the organic matter remains in the soil, the soil is likely to stay loose. But since it slowly decays, you will have to continue to add organic matter -- compost, mulch, or shredded leaves -- in order to maintain the desired texture.

  • Try spading or no-till systems to preserve the texture and organic content of thriving garden soils. Once the soil is loose, light, and rich, minimal disturbance will help preserve the levels of organic matter. Avoid repeated tilling, which breaks healthy soil clumps and speeds up decay.

  • Instead of tilling, loosen rich soil before planting by turning the surface shallowly with a shovel and breaking it apart with a smack from the shovel backside. Very loose soil can be made ready to plant by combing it with a hoe or cultivator.

  • Double-dig garden beds to make high-performance gardens for deep-rooted plants like roses, a tradition in many beautiful English gardens. The average rototiller works the soil only 8 or 10 inches deep and won't break up compacted soil below. But double-digging will.

    Double-digging requires quite a bit of physical labor, but it's a great option for high-performance gardens.
    ©2007 Publications International, Ltd.
    Double-digging requires quite a bit
    of physical labor, but it's a great option
    for high-performance gardens.

    Double-digging requires of a bit of what the British call a stiff upper lip, because it takes a lot of manual labor. Do a little at a time so you don't overdo it, or hire a professional landscaper if you have health restrictions.Start with vacant soil that is stripped of grass or other vegetation. Beginning at one end of the garden, remove a strip of soil a spade's length deep and a spade's width wide. Put it in a wheelbarrow. Use your shovel to turn the soil below it (likely to be one of the heaviest parts of the job) and break it up.Another (sometimes easier) option is to jab a garden fork (like a big pitchfork) into the hard lower soil and rock it around until the soil breaks up. If organic matter is needed, you should add it to the lower level at this point.Do the same thing to the second strip of soil next to the first row. But turn the surface topsoil into the first trench, adding organic matter as desired. Then loosen and amend the exposed subsurface soil. Continue filling each trench from the adjacent row and loosening the soil below. Fill the final strip with the soil from the wheelbarrow.
  • Build raised beds where the soil is too hard, rocky, poor, or wet for plants to grow well. Instead of struggling to change these bad conditions, construct a great garden bed over them. In vegetable gardens, simply mound up planting rows 6 to 8 inches high and 2 to 3 feet wide. (You can walk in the paths beside the planting rows without compressing the raised soil.) Permanent and decorative gardens can be set in handsome raised bed frames built of timbers, logs, rocks, or bricks and varying from 4 inches to 4 feet high. Don't hesitate to ask for professional help for big building projects, which need strong structures in order to last.

Don't take your soil for granted! Take heed of the tips outlined in this article to get the most of your soil and create the garden you've always dreamed of.

Want more gardening tips? Try:

  • Gardening Tips: Learn helpful hints for all of your gardening needs.
  • Annuals: Plant these beauties in your garden.
  • Perennials: Choose great plants that will return year after year.
  • Gardening: Discover how to garden.