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The Pros & Cons of Pesticides & Fertilizers

By Susan Lundman ; Updated September 21, 2017
Healthy plants and trees need nutrients and protection from pests.
Design Pics/Design Pics/Getty Images
Healthy plants and trees need nutrients and protection from pests.
Design Pics/Design Pics/Getty Images

Whether you use organic or inorganic fertilizers and pesticides, your plants will reap numerous benefits if you use the products properly.

Your decisions about whether or not to use plant food or pesticides, and what types of products to use, have as much to do with rewards for plants as they do with environmental sustainability, cost and ease of use.


Fertilizers come in a number of combinations, each with its own set of advantages and disadvantages. Choose from:

  • Simple, or incomplete, fertilizers with only one or two nutrients, such as nitrogen or potassium
  • Complete fertilizers that typically include nitrogen, phosphorus and potassium in various percentages
  • Special blends for specific types of plants, such as acid-loving or fruiting plants
  • Inorganic fertilizers made from synthetic substances
  • Organic, also called natural, fertilizers made from manure, fish emulsion or kelp, among other living or dead materials


  • No soil is perfect for every plant. So fertilizers of all types provide additional food in the soil, keeping plants healthy, vigorous and fruitful.
  • With either a special blend or simple fertilizer, you can target the needs of a specific plant by giving it just the nutrients it requires.
  • Synthetic fertilizers allow plants to absorb nutrients more quickly than they would from unfertilized soil or from natural fertilizers.
  • The dry forms of synthetic fertilizers typically cost less than organic fertilizers.
  • Some synthetic fertilizers have timed-release features.
  • New growth and stronger stems sometimes occur within days when you spray seaweed fertilizers.


  • Too much fertilizer can kill plants -- a problem more common with synthetic fertilizers than organic types.
  • Fresh, non-composted manure can kill plants because it contains salts.
  • Non-composted manure frequently contains weed seeds.
  • It's oftentimes difficult to calculate how much fertilizer to add to plants or lawn because you need to determine square footage and match that to the number of gallons recommended by the fertilizer manufacturer.
  • All fertilizers cost money, with organic ones sometimes costing more than synthetic varieties.
  • Synthetic fertilizers sometime cause crusting on the soil surface.


Although some garden plants are resistant to harmful insects and diseases, many are not and need protection. When barriers and biological controls don't work, try these pesticides:

  • Synthetic fungicide to combat plant diseases such as powdery mildew, rust and molds
  • Insecticide to kill insects and other small pests
  • Herbicide to kill weeds
  • Natural products such as baking soda, copper soaps, bacteria that target insects, sulfur dust or neem oil, which is a pesticide made from a tree.


  • Synthetic pesticides and natural products effectively kill bugs and diseases most of the time.
  • Natural products are less toxic overall than synthetic ones but still can be toxic to a degree.
  • Some natural oils kill disease spores in addition to insect eggs or larvae.


  • Some pesticides are toxic to humans, pets, beneficial insects or other plants in greater and lesser degrees. Reading a product's warning label will let you know how safe the product is.
  • Toxic pesticides have specific storage and disposal regulations you must follow.
  • Determining the amounts of pesticides to use is tricky; they can be ineffective if you use too little or can kill plants if you use too much.
  • Most pesticides need to be applied more than just one time.

For more information on using pesticides and fertilizers, see "Excessive Use of Fertilizers & Pesticides."


About the Author


Susan Lundman began writing about her passions of cooking, gardening, entertaining and recreation after working for a nonprofit agency, writing grants and researching child development issues. She has written professionally for six years since then. Lundman received her M.A. from Stanford University.