THE NATURAL LANDSCAPE Healthy Landscapes for a Healthy Environment Growing Healthy Soil BROUGHT TO YOU BY YOUR LOCAL WATER PROVIDERS: Bryn-Mawr/Lakeridge/Skyway Water & Sewer Cedar River Water & Sewer City of Bellevue City of Bothell City of Duvall City of Edmonds City of Kirkland City of Mercer Island City of Redmond City of Tukwila Coal Creek Utility District Highline Water District King County Water District #20 King County Water District #45 King County Water District #49 King County Water District #85 King County Water District #90 King County Water District #119 King County Water District #125 Lake Forest Park Water District Northshore Utility District Olympic View Water & Sewer Seattle Public Utilities Shoreline Water District Soos Creek Water & Sewer District Woodinville Water District FEED THE SOIL The single most important thing you can do for a healthy garden is to feed the soil with compost and other organic amendments. These materials nourish plants and feed an intricate web of soil life that keeps the soil loose and fertile, and help fight plant pests and diseases. They also purify and store water so that it does not run off and pollute or damage streams and wildlife. The Dirt The mineral portion of the soil supports plants, supplies nutrients, and stores water. The size of soil particles affects how the soil does these jobs. Sand particles feel gritty and are large enough to see with the naked eye. Sand drains quickly, but does not store water or nutrients for plants. Clay and silt are sticky when wet, and dry into dense chunks or fine powder. They hold nutrients and water well, but drain poorly and clay is hard to dig. Loam is a mix of sand, silt and clay plus organic matter. Loamy soils are generally loose, well-drained, and are able to store moisture and nutrients for plants. See soil types on next page. Air and Water These essential elements transport nutrients to plants and carry away wastes. Together they make up about half of the volume of healthy soil. Compact or infertile soil may not have adequate pore space for air and water to move freely to plant roots. Organic Matter and Soil Life The Soil Food Web of dead plant parts plus the soil life that decompose them make up just a small part of the soil volume, but they are the glue that hold soil together. Soil life ranging from microscopic bacteria to earthworms need a steady supply of organic materials to keep the soil loose, moisture holding and well drained. This soil life keeps plants healthy by: - Supplying balanced nutrients - Fighting plant disease and pests - Storing fertilizers for gradual release, and preventing them from washing into streams 206-684-SAVE (684-7283) www.cityofseattle.net/util/onepercent PRINTED ON RECYCLED PAPER For TDD Assistance, call 206-233-7241
- Storing water, reducing runoff and irrigation needs - Making clay soil better drained and easier to work - Trapping and breaking down pesticide residues and polluted runoff IT S EASY TO FEED THE SOIL! Growing healthy soil is as easy as adding compost and other organic amendments to the soil. Use the methods that work best for your garden, and read the rest of this fact sheet for details. Amend the soil throughout the planting area with compost before planting Mulch existing plantings with compost, leaves, grass clippings or woody mulches Use natural organic and slow-release fertilizers Think twice about using pesticides that may damage soil life AMEND THE SOIL BEFORE PLANTING The best way to improve the soil is to mix in plenty of compost or other organic matter before planting. Thoroughly mixing these materials deep into the soil gets the benefits down where the roots need water, air and nutrients. When: Mix in organic matter with existing soil before planting perennials, lawns, trees and shrubs; each time annual beds are replanted, and when dividing perennials or repotting container plants How: Use a shovel or digging fork to mix amendments into the top 6 to 12 inches of soil. Amend large planting areas, not just small holes for each plant. See Choosing the Right Plant fact sheet for more details. Rototill large areas where digging is impractical. Soil Types Clay Sand Loam How Much Amount of compost recommended to amend each 100 square feet of planting area. Lawns Mix compost to 6" depth Gardens Mix compost to 10-12" depth Clay 1" of compost = 8 cu. feet (0.3 cu. yd.) 2" of compost = 16 cu. feet (0.6 cu. yd.) Sand 1-1/2" of compost = 13 cu. feet (0.5 cu. yd.) 4" of compost = 24 cu. feet (0.9. cu. yd.) What: Different types of organic amendments may provide special benefits for certain plants or soil types, as the chart on the next page describes. But any clean organic amendment will improve the soil. The best advice is to use what is cheap, plentiful and easy to get. HOW DO I KNOW IT IS GOOD COMPOST? Poor quality compost can make nutrients unavailable to plants as it finishes decomposing, encourage pests and introduce weeds. Good compost should have: Sweet, earthy smell Dark brown or black color No weed sprouts, mushrooms or other growths Fibrous texture (like peat); not gritty, woody, greasy or powdery No steamy or hot spots in piles
WHICH SOIL AMENDMENT TO USE? Amendment Choice Pros and Cons Best all-purpose materials Composted Yard Debris, Recycled. Easy to buy. Balanced nutrients. Yard trimmings can Biosolids or Barnyard Manure be composted at home. Leaves (composted or fresh) Rich in nutrients. Free. Usually few weed seeds. Fresh Barnyard Manure Especially good for sandy soil, annuals and non-woody perennials. Nutrient rich, but may contain weeds or harmful salts. Best if composted or mixed into soil weeks before planting. Other materials Aged Bark or Sawdust Peat Moss Coconut Coir Topsoil Mixes Improves drainage in clay soils. Good for trees and shrubs. Fresh materials must be composted until dark, or they can tie up nutrients and inhibit plant growth. Improves moisture and nutrient storage in sandy soils. Does not support soil life. Production may destroy rare peat bog plants. Improves moisture and nutrient storage in sandy soils. Does not support soil life. Renewable product from coconut palms. Good for raised beds on top of compacted or poorly drained soil. Often contain poor fill soil or weeds. Best to use mixes containing only compost and clean sand. MULCH ESTABLISHED PLANTINGS: Mulching with organic materials like compost and bark makes everything you do in the garden easier. A thick layer of mulch inhibits weed germination. It also makes weeds easier to pull. It keeps the soil loose so water is easily absorbed, and reduces evaporation so you can water less. Mulch also prevents soil erosion that can choke streams and fish with sediment. Earthworms and other soil creatures gradually break down mulch and mix it into the soil to nourish plants. When: Apply annually or as needed. Mulch in early summer to conserve moisture, prevent weed seeds from sprouting and feed plants. Mulch in fall to protect soil from erosion, smother weeds and hold warmth. Where: Mulch entire annual and perennial planting beds and the surface of containers. Cover entire tree and shrub planting beds, or make mulch rings at least 3' wide around each plant in lawns. How: Remove weeds and grasses before spreading mulches. Keep mulch a few inches away from stems, crowns and trunks to prevent rots and pest damage. Use porous weed barriers to smother aggressive weeds. How Much: Screened compost, leaves, medium or fine ground bark, sawdust: 1/2' to 2" Coarse shredded bark, wood chips or tree trimmings: 2 to 4" deep Grass clippings: 1/2' to 1" Note: One cubic foot of mulch will cover a 12-square foot area one-inch deep. One cubic yard will cover a 324-square foot area one-inch deep or 108-square foot area three inches deep.
What: The best mulch for each garden area depends on the plants and what is readily available. The best mulches for shrubs and trees are coarse woody materials that protect the soil for a year or longer, and slowly release nutrients for steady growth. Annuals and perennials benefit from mulches like compost, fresh manure or grass clippings which feed plants quicker and can be mixed into the soil without tying up nutrients. Fall leaves are a good all-purpose mulch. They can be composted or run over with a lawn mower for a finer texture. WHICH MULCH TO USE? Mulch Choice Annuals/Perennials/Fruits and Roses Composted Yard Debris, Bark, Barnyard Manure or Biosolids Fresh Barnyard Manure, Leaves and Grass Clippings Other Shrubs and Trees Fresh Bark Sawdust / Wood Shavings Wood Chip / Shredded Prunings Weed Barriers Cardboard or newspapers layered under other mulch materials Woven Fabric Weed Barrier Pros and Cons Neat appearance. Use good quality compost free of weeds. Free or inexpensive. May spread weed seeds or disease. May be unattractive. Tidy appearance. Readily available. May inhibit growth of some plants. May be unnatural looking. May be unattractive. Best if aged. Natural look. Free and readily available. May spread weed seeds or disease. May be unattractive Decomposes to feed soil. Aggressive weeds may grow through it. Long lasting. May get tangled in weeding hoes. FERTILIZE MODERATELY WITH NATURAL ORGANIC AND SLOW RELEASE FERTILIZERS Proper fertilizing grows healthy, easy-to-maintain plants. Too much fertilizer can produce excess growth that is easily damaged by pests, wind, frost and drought. Many of the nutrients in quick release fertilizers are likely to wash off or through the soil to pollute lakes, streams and groundwater. Most established trees and shrubs do not need regular fertilization. Mulching can provide all their nutrient needs in most cases. Even heavy feeders like roses, annuals and flowering perennials get adequate nutrients though yearly compost applications. What: Natural organic and slow release fertilizers gradually release nutrients as plants need them, so less is washed away to pollute surface waters. Natural fertilizers include rock phosphate and other minerals, plant products such as alfalfa meal, and animal byproducts like bone or fish meal. Most nutrients in natural fertilizers must be digested by bacteria before they dissolve in water and plants can use them. They are slowly released when warm soil stimulates the bacteria, and when actively growing plants need them. Synthetic fertilizers like urea and ammonium sulfate quickly dissolve in water. They wash through the soil with rain or irrigation if not immediately used by plants or absorbed by organic matter. Slow release fertilizers such as sulfurcoated urea become available as outer coatings are dissolved by moisture and soil bacteria that are most active when plants are actively growing. Though natural and slow release fertilizers can cost more; they may be a better value - and safer - since more nutrients actually feed the plants, instead of washing into streams or groundwater. Look for the words natural organic or slow release on the fertilizer bag.
FERTILIZER TIPS Lawns Annual Gardens Trees and shrubs Best Fertilizer: Fertilizer with 3 parts Balanced fertilizer (5-5-5, When plants are stunted or nitrogen, 1 part 10-10-10, etc), or soil test show other signs of need, phosphorous, 2 parts recommendation or as indicated by soil tests potassium. (6-2-4, 18-6-12, etc). Lime Lime When: September, if once a year; May At planting, and mid-season When growth starts in spring, and September if twice a year and mid- summer How: Fertilizer spreader Mix into soil below transplants Scratch into soil below outer and seeds, or in shallow bands edge of branch growth, and along rows of plants. cover with mulch. How Much: 1 lb. nitrogen per / Follow label or soil test Follow label or soil test 1000 square feet. recommendation recommendation How Much: Fertilizing should ideally be based on observed plant needs or soil tests. If you would like to have your soil tested, call WSU King County Cooperative Extension at (206) 296-3900 for a list of soil testing labs and sampling instructions. To reduce nutrient runoff if using soluble fertilizers, consider applying half the suggested amount, twice as often as recommended. For information about composting at home, or about compost bin discounts call: For Seattle residents, (206) 633-0224 For King County residents outside Seattle, (206) 296-4466 Additional Resources Let It Rot: The Gardener s Guide to Composting, by Stu Campbell, Storey Books, 1998. The Mulch Book: A Complete Guide for Gardeners, by Stu Campbell and Donna Moore (Editor), Storey Books, 1991. Worms Eat My Garbage, by Mary Applehof, Flowerfield Press, 1997. Start With the Soil : The Organic Gardener s Guide to Improving Soil for Higher Yields, More Beautiful Flowers, and a Healthy, Easy-Care Garden, by Grace Gershuny, Rodale Press, 1997.