Home gardens

What should I consider before using fertilizers and pesticides at home?

Walking through the aisles of any home improvement or garden store, there is a seemingly endless array of products for your lawn and garden. Before making your selection though, there are few points to consider:

  • What are you trying to fix or improve?
  • What is the cause of the problem?
  • How big of area do you need to treat?
gardener adding fertilizer to garden
When choosing to use fertilizer, follow these steps to success. Credit: ASA/CSSA staff

No matter which product you end up selecting, the most important step before applying is to thoroughly read the label and all instructions. We tend to think that just because these chemicals are readily available, that we can use them freely. But, just like you look at the dose of your pain reliever, you should check to see the best dose of fertilizers and pesticides!

Over- and under-application of the product can both cause problems. Over-application of fertilizer can cause excessive growth and poor fruit production. Over-fertilizing can also increase disease pressure – excess leaf growth can trap excess moisture on the plant. Under-application of fertilizer can lead to disappointing results and wasted money. With pesticides, over-application can harm beneficial insects and under-application can just prolong the issue.


If you are looking to fertilize your lawn or garden, you need to know what nutrients are already in the soil before applying more. You might be able to save some money and apply less fertilizer. Or, you might just need to add one specific nutrient, and not others.

A simple way to get reliable results is to have your soil tested. Contact your local university extension service for information on testing your soil. It’s usually a matter of scooping up soil from a few areas of your yard, and sending it in to the lab!

Fertilizer label
Fertilizer contents are denoted by the guaranteed analysis which is displayed as the ratio of Nitrogen (N), Phosphorus (P) and Potassium (K). In this product, there is 5% nitrogen, 10% phosphorus and 10% potassium, or 5-10-10. Getting a soil test done before adding fertilizer helps you save money and apply only what your plants need. Credit: T Wilson.

Once you have the results of your soil test, then you can make your fertilizer selection. Many common household fertilizers are a mix of nitrogen (N), phosphorus (P), and potassium (K). The nutrient content of the fertilizers are noted by the guaranteed analysis of the nutrients. This is presented as N-P-K. For example, if the guaranteed analysis is 5-10-10, this means there is 5% nitrogen, 10% phosphorus, and 10% potassium. Some may have micronutrients such as sulfur or boron. Depending on what you are fertilizing, you may need different formulations of nutrients. Your local university extension service is a fantastic resource for determining fertilization rates for different fruits, vegetables, and lawns for your region.

To determine the size of your area that you are fertilizing, multiply length times width. For example, if your garden is 30ft long by 10ft wide, the area is 300 ft2.

To calculate area: Length (ft) x Width(ft) = Square Feet


apple with worm damage
Damage to an apple from Cottling Moth. Photo: Oregon State University Extension Service.

Pesticides, when used correctly, are safe for use in your lawn and garden. As with any household chemical, it is critical to follow the label instructions and exercise caution when handling. Knowing which pests you are trying to control is the first step to selecting the best product. Your area Master Gardener’s group and/or university extension service can help you identify the source of your problem. If used carelessly, pesticides can cause harm to humans, animals, wildlife, fish, insects, and plants. Improper use can pollute air, water, and soil.

Some precautions to take when applying pesticides include:

  • Wearing the proper clothing to protect yourself: long sleeves, pants, gloves, and waterproof boots. Read the label carefully in case further personal protective equipment (PPE) is needed.
  • Use only the amount needed for the area.
  • Keep children and pets out of the area during application.

If your garden is experiencing consistent problems with pests, you might consider why this is happening. Do you need to move your tomato patch to a new area, and grow kale there for a year or two? Or perhaps your plant spacing is too tight, holding in moisture. All plants do best in healthy, nutrient-rich soil, so having your soil tested for nutrients is a good idea. Yearly mulching, use of compost, and overall soil maintenance can help the overall health of your plants.

Answered by Tracy Wilson, Central Oregon Research Center

About us: This blog is sponsored and written by members of the American Society of Agronomy and Crop Science Society of America. Our members are researchers and trained, certified, professionals in the areas of growing our world’s food supply while protecting our environment. We work at universities, government research facilities, and private businesses across the United States and the world.

3 replies »

  1. I am looking into using fertilizer in the garden since I am growing crops when I came across this article. It really helped when you said that in order to save more money, a person has to know the nutrients that are lacking in the soil and use a fertilizer that meets that. I will make note of that since I do want to save money, and I do not wish to overdose my soil with fertilizer.

  2. Thanks for explaining that we shouldn’t use too much fertilizer, since over-application can actually lead to disease and unhealthy leaf growth. My husband and I want to start gardening more, so I’ve been doing some research on how using fertilizers can help us. I’m glad I read your article because I didn’t previously realize that too much fertilizer could be a bad thing.

Leave a Reply