Rob Last, Horticultural Agent – Allendale, Bamberg, Barnwell, and Hampton
Fertilization for plants can be essential to ensure optimal growth, development, display (for ornamentals or yields of fruits, nuts, and vegetables. In a nutshell, fertilization relies on four principles referred to as the four R’s. The Right Rate of the Right Product at the Right time, applied to the Right Place.
- Determining the Right Rate and Right Product?
Firstly, taking a soil test for any crop is vital. The recommendations from the approved laboratory will factor in the soil analysis results. The soil analysis will help identify the right product and the Right rate.
- Determining the Right Place?
Broadcast applications cover large areas and are great for lawns and ornamental beds. When we consider trees, applications should be made 2 feet away from the trunk and extend to the edge of the dripline of the foliage. Confining applications to this zone ensure the fertilizer is utilized and not lost to the broader environment.
- Determining the Right Time?
- Spring
Phosphorous and Potassium applications. Often the fertilizers available are balanced, such as 10:10:10, and are likely to contain Nitrogen. Nitrogen should only ever be applied to plants when they are actively growing. During active growth (leaves present), the plants take up the nitrogen applications preventing losses from leaching. So, for ornamental shrubs and trees, the first application of Nitrogen is made when buds are breaking and plants are beginning to leaf out.
Any additional Nitrogen required can either be applied six to eight weeks later. Splitting nitrogen applications is beneficial in preventing leaching losses. For fruit and nut trees, make the first application when buds break. Delay the second Nitrogen application is until after fruit/nut formation. The second application provides Nitrogen to maintain leaves for a longer time allowing for resource generation for the following year’s crops.
For turfgrasses, delay fertilizer applications until achieving full green-up. Typically, full green-up occurs in early May. Fertilizing warm-season turfgrasses too early Is detrimental to the lawn, increasing the potential for frost damage from the lush new growth. As an aside, avoid using feed and weed products; the timings for weed control are March, while fertilizer applications occur in May. For more information, view The Home Garden Information Center website at HGIC or contact your local Extension Agent.
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