Lawn Fertilization

Why Fertilization Is Necessary

Some may think that since all necessary fertilizers were applied during lawn installation, there's no need to revisit the topic. After all, a lawn is not a vegetable garden from which you harvest crops every year.

Nevertheless, regular mowing gradually depletes the soil's nutrient reserves. If this loss is not replenished in time, the grass will turn pale, become thin and sparse. It will be more vulnerable to pests and more easily invaded by tough weeds.

Essential Nutrients for Lawns

As grass grows and develops its root system, lawn plants absorb nutrients in different ways. Each element performs essential and supportive functions:

• Nitrogen promotes growth, thickens the grass, enhances freshness, and improves color.
• Phosphorus strengthens roots, expands the nutrient absorption area, and stimulates lateral shoot development.
• Potassium increases resistance to diseases, drought, and other adverse weather conditions.

Nitrogen

Nitrogen is the most rapidly leached from soil by plant roots. Therefore, nitrogen-rich fertilizers should be applied in spring and summer, when grass growth is most intense. In autumn, fast growth is undesirable — nitrogen content in fertilizer should be minimal.

Nitrogen fertilizers are classified by release speed: fast-acting and slow-release. Fast-acting types are used in spring, while slow-release forms are preferred in autumn.

Phosphorus

Phosphorus is equally essential for grass. Its compounds should be added to lawn soil each season. It helps grass start growth earlier in spring and promotes more lateral shoots in autumn. Therefore, it is mostly applied in spring and early autumn.

Potassium

Potassium is less critical than nitrogen or phosphorus, but it's very beneficial for normal growth, maintaining green color, and overall plant strength. It is best applied in spring or autumn.

Choosing the Right Fertilizers

Fertilizers for lawns can be organic or mineral. Mineral fertilizers are more effective but may harm the environment. For best results, use specially formulated, balanced mixtures designed for lawn grass. Choose based on soil condition and texture. Always follow instructions on the packaging.

Organic fertilizers act more gently, cause less harm to soil organisms and beneficial insects. However, they must be applied more frequently, and may introduce weed seeds to the lawn.

One good source of organic nitrogen is clippings. Simply leave them on the lawn after mowing. This method works especially well when combined with aeration, which is recommended annually.

Organic phosphorus, suitable for lawns, is found in bone meal. Apply it in autumn, scattering by hand — about one handful per square meter.

If the soil under the lawn is acidic, wood ash makes a good potassium fertilizer. Spread it over the surface in autumn — up to 10 kg per 100 square meters. Potassium is also present in compost, which contains significant nitrogen. Therefore, compost should only be used in spring, spread evenly and worked into the soil with rakes.

Autumn is especially critical for phosphorus and potassium fertilization. The best option is using specialized autumn-specific fertilizer kits. Mineral options include superphosphate and potassium sulfate; organic options include bone meal.

Be cautious with nitrogen-rich fertilizers in autumn. They may trigger fast growth, which harms winter survival. In extreme cases, use slow-release nitrogen forms early in autumn.

Fertilization Best Practices

• Avoid fertilizing during prolonged drought.
• Grass should be dry, and soil moist before fertilizing. If no rain has fallen recently, water the lawn thoroughly, then wait for moisture to absorb and grass to dry. Then begin spreading fertilizer. Water only after about 1.5 days to prevent leaching.
• Apply dry fertilizers evenly to avoid burns and unsightly brown spots. Use a spreader for best results.
• Liquid fertilizers can be applied with a watering can, but a pump-type sprayer with a hose is better.
• Pay close attention to liquid fertilizer concentration: lower is safer. A too-concentrated solution can cause more harm than benefit. It’s better to slightly under-fertilize than to repair damage from burns later.