Gardening with Allen: Apply fertilizer to help out lawn

My lawn has not come through this hot, dry summer very well. Is now a good time to fertilize?

Lawns will naturally start looking better soon as they respond to the fall rains. Fertilizer right now will make them look even better. By late October or November grass is green but stops growing. Fertilizing in October increases the green color without stimulating growth. It also keeps the lawn greener during the winter.

Root growth is still very active, so grass plants take up the fertilizer, especially nitrogen. The nitrogen is used to make amino acids which are stored in the roots and crown. The amino acids are available for early spring growth before roots can actively take up nitrogen.

The three major fertilizer ingredients are nitrogen, phosphorus and potassium. Nitrogen is the most important for leaf growth so most lawn fertilizers contain 15 to 25 percent nitrogen. According to Washington law, there is no phosphorus in lawn fertilizers. Most brands of lawn fertilizer have a fall blend, which contains about half as much potassium as nitrogen for better winter growth. Iron is another nutrient which is important for lawn growth and dark color. Only small amounts as low as 1 or 2 percent are adequate.

Because of heavy rainfall, Northwest soils are quite acid. Lawns will benefit from a yearly application of lime or similar soil-sweetening products that contain calcium. Up to 5 pounds per 1,000 square feet can be applied. Rhododendron, azalea, camellia, heather, mountain laurel, magnolia, holly, dogwood, andromeda, leucothoe, blueberry and raspberry prefer acid soil and should not be treated with lime.

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