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IRRIGATION Established lawns in Western Washington use about one inch of water per week during the peak growing


season (July-September). Water infrequently, but deeply. Light, frequent irrigation encourages weeds, undesirable grasses, surface rooting and disease problems. Irrigate slowly, so the water doesn’t run off. Overwatering can wash pesticides and fertilizers into storm drains. Allow the top two inches to dry before watering again; don’t over-water. Saturated solids encourage surface rooting and weak turf. A healthy, established lawn will turn brown in the summer, but will survive if some moisture remains in the oil. Weeds can get established during the summer brown-out and the turf will not withstand rough use like an actively growing lawn.


Water infrequently, but deeply. Light, frequent irrigation encourages weeds.


MOWING Improper mowing can be stressful to your lawn and make it more susceptible to pests and diseases.


Remove only 1/3 of the leaf blade at one cutting and mow at 1 ½” to help limit thatch build-up. Moderate grass heights shade the soil and help prevent water loss and weed seed germination. Keep mower blades sharp; dull blades shred the grass and make it more vulnerable to problems. Leave clippings on the lawn as grass clippings provide many nutrients, reducing the need for nitrogen fertilizer by as much as 25% if you fertilize regularly.


Clippings reduce the need for nitrogen fertilizer by as much as 25%.


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FERTILIZING Generally, lawns in our area need four pounds of nitrogen per 1000 sq ft each year, divided into four


applications. The two most important applications are on September 1 and June 15, with the other two applications made around mid-April and mid-November. Use a fertilizer with about a 3:1:2 ration (6:2:4, 10:3:6, etc.) The first number represents the percentage of nitrogen in the fertilizer. Use it to figure the amount needed to get 1-pound actual nitrogen for each application. For example, you would need 20 pounds of fertilizer with 5% nitrogen to get one pound of actual nitrogen. Too much nitrogen will promote excess growth, making the lawn more susceptible to pests and diseases. Always clean up fertilizer from sidewalks and driveways. Use organic fertilizers in June or September, not during November-April since they can leach with cool soils and heavy rainfall. Use other slow-release fertilizers such as


sulfur or polymer-coated areas at any time. These products release nutrients slowly over a longer period, allowing the grass to absorb nutrients more efficiently.


Use organic fertilizers in June or September, but not November-April as they can leach in cool soil and rain.


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WEEDS Proper fertilization, mowing and watering will usually produce a thick lawn with few weeds. You may find


you can tolerate some weeds, particularly those that blend with turf. Broadleaf weeds like dandelions can be removed by hand. Selective spot treatments may be useful in certain situations, especially for perennial weedy grasses. Re-seed any bare spots that result from weeding.


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LAWN AERATION Aerate spots where you cannot push a screwdriver 6” into the soil, where water pools, grass looks thin


or where traffic is heavy. Before you begin, irrigate deeply, then allow the soil to dry slightly before aerating. Soil should be moist 6” down, so the aerator will penetrate as deeply as possible. Use either a foot-operated or motorized hollow- tine aerator that removes plugs of soil. Leave the plugs on the lawn and break them up with a rake.


Aerate spots where you cannot push a screwdriver 6” into the soil,


THATCHING Thatch is living and dead grass stems, shoots, and roots, which accumulate on top of the soil. Thick


thatch prevents air, water, and nutrients from reaching the soil. Regular fertilization, proper irrigation and correct mowing height can help prevent thatch buildup. If thatch is more than 1/2” thick, remove it with a rake or rented thatching machine. For best results, remove thatch in early spring or late summer.


For best results, remove thatch in early spring or late summer.


Show us how you SHINE by sharing photos of your finished landscaping projects. Send your photos to info@wscai.org so we can include them in a future issue. Happy landscaping!


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