What Experts Are Saying
What the Experts say from Grow Smart, Grow Safe: A Consumer Guide to Lawn and Garden Products, Sixth Edition, is a joint publication of Metro regional government in Portland, Ore., and the Local Hazardous Waste Management Program in King County, Washington:
- Kick the chemical habit or use slow-release products. Synthetic chemical fertilizers typically feed plants fast but get used up or washed away quickly, unless they were manufactured to be slow-release or time-release. Synthetics also typically provide few if any secondary nutrients or micronutrients. Because they commonly contain very high N-P-K percentages, it can be tricky to avoid overfertilizing. This may lead to plant stress, pest and disease problems and polluted rivers, streams and groundwater. Organic or natural fertilizers are an excellent alternative.
- Choose organic and natural fertlizers. Organic fertilizers are made from natural products. Typically organic fertilizers are slowrelease, requiring less-frequent application. They are less likely to run off your soil and pollute rivers and streams and more likely to contain essential micronutrients and vital organic matter.
- More is not better. Overfertilizing with any nutrient can cause plant stress, resulting in pest and disease problems. The excess material also can run off into local rivers, groundwater and streams, polluting them. Underfertilizing can bring about poor plant performance. Balance is the key. Two good rules of thumb: Don’t fertilize at all, unless your plant’s performance or a soil test indicates a need, and never apply more than recommended on the label.
- Choose lawn fertilizers with an N-P-K ratio of 3-1-2. Lawns growing in typical Pacific Northwest soil will benefit most from a fertilizer with an N-P-K ratio of 3-1-2 or multiples thereof. For example, a 6-2-4 ratio will help a lawn thrive.
- Weed and feed is a pesticide. Most weed and feed contains both a synthetic fertilizer and three different herbicides (herbicides are pesticides). Protect your family and local waters by instead pulling or spot-treating individual weeds.
- Fertilizers with larger numbers (such as 29-2-3 or 18-16-10) are typically synthetic fertilizers. They can cause plants to grow rapidly but are often quickly depleted. They also are more likely to run off into lakes and streams or leach into groundwater polluting the environment.
- Time-release varieties pose less risk of runoff. If you use high-nutrient fertilizers, look for words such as “pelletized,” “coated” or “slow-release” on the label.
- Fertilizers with smaller numbers (such as 4-2-8 or 5-7-2) are likely organic fertilizers. These products tend to feed your plants slowly over time. They are often made from natural ingredients. They also may contain important secondary nutrients and micronutrients such as calcium and iron. Look for words such as “natural” and “organic” on fertilizer labels."