Is it necessary to fertilize annuals growing in containers?
Plants in containers need to be fertilized on a regular basis as nutrient levels in potting mixes quickly fall due to absorption by plants and leaching during watering.
Many commercial potting mixes contain a slow release fertilizer. However, slow release fertilizers seldom last the entire growing season. When using a potting mix containing a slow release fertilizer, begin to fertilize plants when plant growth slows or the color of the foliage fades. A granular fertilizer can be applied to the soil surface or plants may be fertilized with a water soluble fertilizer. Check the product label for application rates and frequency.