Fertilizing Clover

Clover is a legume that you can use to organically improve the nitrogen content of soils. Clover rarely requires fertilization since it can use nitrogen from the atmosphere thanks to a symbiotic relationship with microorganisms in the soil. In most cases, clover suffering from a nutrient deficiency only needs fertilization with phosphorous, potassium, sulfur or a micronutrient.

Nitrogen Fixation

Clover is capable of drawing nitrogen from the atmosphere and the soil but will take nitrogen from the soil first. When there is not enough nitrogen in the soil to support a clover plant, it begins to draw nitrogen from the atmosphere so long as the right type of bacteria is present in the soil. Inoculating your clover seeds with the bacteria Rhizobium when you plant clover ensures that it can supply itself with nitrogen. In most cases you will not need to apply nitrogen fertilizers to clover that is treated with this bacteria. The best time to inoculate your clover seeds is immediately before planting time, using refrigerated inoculum mixed with sugar water to ensure that it sticks to the seeds.

Major Nutrients

Your clover requires relatively large amounts of phosphorus and potassium to sustain healthy growth. The most effective way to fertilize clover is using a broadcast spreader to apply dry fertilizer over the soil. This method allows you to control the rate and quantity of fertilizer that you apply to your clover. Preforming a soil test on your soil before you fertilize will provide you with an accurate measurement of how much fertilizer your clover needs. Soil testing kits are commonly available from university extension offices and commercial testing laboratories.


Soils that are low in organic material are often deficient in the micronutrients boron and sulfur. If you have a sandy soil and your clover is not growing well, consider performing a soil test to determine which micronutrients your soil is lacking and how much you need to apply. You can correct sulfur deficiencies using elemental sulfur or calcium sulfate. An application of sodium borate supplies boron in the soil but is toxic to plants in high concentrations. Your clover also requires iron, zinc, manganese and copper to grow. In most cases, these nutrients are naturally present in the soil. If a soil test indicates that your soil is deficient in one of these nutrients, you can use a combination fertilizer containing the micronutrients your soil is lacking.

Soil Acidity

Most types of clover grow in soil with a pH rating between 6 and 7. Red clover will provide the best growth in a mildly acidic soil with a pH of approximately 6.0. Sweet clover prefers a soil pH of 6.5, while white clover can support a pH level as low as 5.8. If a soil test indicates that your soil pH is to acidic, you can use lime to raise your pH level. If you have an alkaline soil (a pH above 7), you can increase its acidity using sulfur or aluminum sulfate.