CORRECTION: Roger misstates the functions of Potassium and Phosphorus in this video. Potassium helps with chemical reactions and Phosphorus helps with root growth.
The right fertilizer can make your lawn healthy and vibrant, but narrowing down the available choices can be overwhelming. Understanding fertilizer basics and determining what your plants need can help you to make the right pick. Read our guide below for tips on how to choose the right fertilizer, how to properly apply your choice to your outdoor space, and how to keep yourself safe during application.
Understanding Fertilizer Basics
Fertilizers give plants the nutrients they need to thrive. Without adequate fertilization, your plants might not reach their full potential.
The three primary nutrients in fertilizers are Nitrogen (N), Phosphorus (P), and Potassium (K), which are commonly referred to as NPK. Read what each does below.
- Nitrogen (N): Promotes leaf growth and green color
- Phosphorus (P): Supports root development and flowering
- Potassium (K): Enhances overall plant health and disease resistance
The numbers you might find on a fertilizer package represent these elements. A fertilizer labeled 15-30-15 contains 15% nitrogen, 30% phosphorus, and 15% potassium, for example. The remaining percentage is made up of filler materials that will help you to spread the fertilizer evenly.
Understanding NPK ratios will help you to select the right fertilizer based on your plants’ needs. Fertilizers come in various forms, and each has unique advantages. Read more about different types of fertilizers below.
- Granular: Slow-release formulas that are best for long-term feeding
- Liquid: Fast-acting and plants absorb it easily
- Organic: Has a lower percentage of nutrients than other types, but it’s beneficial for soil health
- Water-soluble: Powder or crystals that dissolve in water
Determining Your Fertilizer Needs
Determine your soil’s needs and nutrient levels to help you pick the right fertilizer.
Soil Testing
A soil test determines which nutrients your soil lacks, your soil’s pH, and your soil’s nutrient content. You can get soil testing kits from garden centers, or you can contact your local cooperative extension office for professional testing services.
Plant-Specific Requirements
Different plants have different nutritional needs. Consider the following general guidelines:
- Flowering plants: Benefit from phosphorus-heavy formulas that encourage blooming
- Lawns: Usually require nitrogen-rich fertilizers
- Trees and shrubs: Typically require slow-release fertilizers that have lower nutrient concentrations
- Vegetables: Usually need a balanced NPK ratio for overall health and productivity
Choosing Between Synthetic and Organic Fertilizers
You can choose either synthetic or organic fertilizer options. Synthetic fertilizers are manufactured chemical products that provide precise nutrient ratios, while organic fertilizers are made of natural materials such as compost, bone meal, and fish emulsion. Both have their pros and cons, which you can read more about below.
| Type | Pros | Cons |
|---|---|---|
| Synthetic | Consistent and predictable results Higher nutrient concentrations More affordable Quick-acting | Can harm beneficial soil microbes if you overuse it May lead to nutrient runoff if you don’t apply it correctly |
| Organic | Environmentally friendly and sustainable Improves soil structure and promotes beneficial microbes Often contains trace minerals that benefit plant health Releases nutrients slowly, and reduces the risk of over-fertilization | Lower nutrient ratio, which helps some plants but hurts others More expensive than other types Slower and less consistent results |
Fertilizer Application Methods and Timing
You can maximize the benefits of your fertilizer and minimize potential harm to your plants and the environment if you take the time to apply your fertilizer properly.
Granular Fertilizers
Granular fertilizers provide a steady nutrient supply, and support consistent growth over time. Distribute granular fertilizers evenly with a spreader. Water the area thoroughly after you apply the fertilizer to help the nutrients penetrate the soil. These slow-release formulas are ideal for lawns, perennial gardens, trees, and shrubs.
Liquid Fertilizers
Apply liquid fertilizers with a hose-end sprayer or watering can. They are excellent for container plants, window boxes, foliar feeding, and quick nutrient boosts.
Timing and Frequency
When you apply your fertilizer and the frequency depends on the variables below.
- Fertilizer formula (quick-release vs. slow-release)
- Plant type and growth stage
- Season and climate
- Soil conditions
Always follow the manufacturer’s instructions, and avoid over-fertilization, which can harm plants and the environment.
Safety Considerations When Working With Fertilizer
Consider the tips below to keep yourself safe while applying fertilizer:
- Avoid inhaling fertilizer dust or fumes
- Store fertilizers in a cool, dry place that’s out of the reach of children and pets
- Wash your hands thoroughly after use
- Wear gloves and protective eyewear when handling fertilizer
You can damage plants if you overuse fertilizers. Over-fertilization can lead to plant burn, which damages roots and foliage. Follow the tips below to prevent this:
- Avoid fertilizing during periods of drought or extreme heat.
- Follow application instructions carefully.
- Use slow-release formulas for a more gradual nutrient release.
- Water plants thoroughly after applying fertilizer.
Additional Considerations When Using Fertilizer
Consider the variables below to get the best results from your fertilizing routine.
Seasonal Adjustments
Plants have different nutritional needs as the growing season changes. Early-spring applications promote growth, while late-season applications support root development. Adjusting your routine according to the season enhances plant health.
Environmental Impact
Consider the environmental implications of your fertilizer choices. Synthetic fertilizers can harm local waterways and lead to nutrient runoff. Use organic fertilizers precisely to minimize this impact.
Integrated Nutrient Management
Combining different types of fertilizers can offer your plants balanced nutrition. You can use a quick-acting liquid fertilizer for immediate nutrient needs and a slow-release granular fertilizer for sustained feeding, for example.