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 Fertilizers are materials added to the soil to provide essential plant nutrients including those listed below.
Nitrogen (N) fosters strong leaf growth.
Phosphorus (P) enhances roots and flowers.
Potassium (K), also known as potash, contributes to overall plant health.
Secondary nutrients such as calcium and sulfur foster strong stems and more.
Micronutrients such as copper and zinc contribute to plant health in a variety of ways.
More is not better. Over-fertilizing causes problems.
- Too much fertilizer can cause plant stress, resulting in pest and disease problems.
- Excess fertilizers can run off into local rivers, groundwater and streams, polluting them.
- The fertilizer label gives guidance on how much to use and how to use it safely.
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.
- Never apply more than recommended on the label.
Choose organic and natural fertilizers.
- Organic fertilizers are made from natural products, such as plant parts, animal wastes or byproducts, minerals or rocks.
- Most are slow-release, requiring less-frequent application.
- They are less likely to run off your soil and pollute rivers, lakes, streams and groundwater.
- And they are more likely to contain essential micronutrients and vital organic matter.
Kick the chemical habit, or use slow-release products.
- Choose slow-release or time-release synthetic fertilizers, or natural organic fertilizers.
- Many synthetic chemical fertilizers feed plants fast but get used up or washed away quickly.
- Synthetic fertilizers don't typically provide secondary nutrients or micronutrients.
- Synthetic fertilizers sometimes contain high N-P-K percentages; it can be tricky to avoid over-fertilizing.
Apply fertilizers carefully. Some of the ingredients are serious water quality problems.
- Avoid fertilizing right before heavy irrigation or a rainstorm, so your fertilizers don’t wash away into storm drains, rivers, lakes or groundwater.
- Be careful not to get fertilizer on sidewalks or other hard surfaces.
- Keep kids and pets off freshly fertilized lawns to avoid chemical exposure.
Store fertilizers, and all garden chemicals, safely.
- Keep products in original containers so you have the directions and safety information.
- Store in locked cabinets out of the reach of children and pets.
- Keep products dry and in leak-proof tubs or garbage cans to contain spills.
- If you have a well, the well-house is not the place to store chemicals.
Don’t keep garden fertilizers and pesticides you won't use. Take them to your local household hazardous waste collection site.
Grasscycle, it's free fertilizer! Leave clippings on the lawn when you mow.
- You get a free, natural supply of nitrogen and other nutrients.
- You save time and effort by not having to rake or bag the clippings.
- Mulch mowing does not contribute to thatch.
Plants need a variety of nutrients to survive. Fertilizer labels indicate the percentage of sources for each of the three major nutrients nitrogen, phosphorus and potassium.
Synthetic fertilizers often have higher ratios (such as 29-2-3 or 18-16-10)
- They can cause plants to grow rapidly but nitrogen is often quickly depleted.
- Because they are water-soluble they are more likely to run off into lakes and streams or leach into groundwater, polluting the environment.
Time-release varieties are synthetic but pose less risk to the environment.
- Look for words such as "pelletized," "coated" or "slow-release" on the label.
- Look for a higher percentage of Insoluble nitrogen.
- Feed your plants gradually but may still be toxic to the soil biology.
Organic fertilizers usually have smaller ratios (such as 4-2-8 or 5-7-2).
- Look for words such as "natural" and "organic" on fertilizer labels.
- These products tend to feed your plants slowly over time.
- They enrich your soil making it healthier too.
- They are often made from natural ingredients such as seeds, kelp or mineral deposits.
- They also may contain important secondary and micronutrients such as calcium and iron.
Choose lawn fertilizers with an N-P-K ratio of 3-1-2 or 3-0-1.
- 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.
- Look for "no phosphorus" lawn fertilizers with an N-P-K ratio of 3-0-1 too. To help protect water quality, many manufacturers are now producing lawn fertilizers without phosphorus.
Weed and feed is a pesticide. We don't list weed and feed with the fertilizers in Grow Smart, Grow Safe.
- It is both a fertilizer and an herbicide.
- Herbicides are pesticides and are designed to kill weeds.
- Most weed and feed contains both a synthetic fertilizer and two or three different herbicides.
- Learn more about weed and feed here (Weed chapter)
- Protect your family and local waters by instead pulling or spot-treating individual weeds.
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