Steamboat Springs As Audrey said to Seymour in the play "The Little Shop of Horrors," "FEED ME!"
Our plants may not be able to talk to us in spoken language like the fictional plant named Audrey did to her flower shop owner, but they do speak to us nonverbally. If we're paying attention, our plants will indicate their need for nutrients to aid their growth. A soil test can also help you determine which nutrients are missing in your garden soil.
While there are 16 different nutrients that our plants need to develop healthy roots, flowers and fruits, the big three are Nitrogen (N), Phosphorous (P), and Potassium (K). Plants use large amounts of Nitrogen to grow foliage and attain a beautiful green color. Phosphorous aids in root formation and flower development while Potassium helps improve drought stress, winter hardiness and disease resistance.
Generally, plants obtain most of the nutrients they need from the soil, water and air. While soils vary across Routt County, we typically have marginal Nitrogen and Phosphorous and adequate Potassium. Your soil pH, its organic matter and amount of clay also affect its ability to hold nutrients. So, there are times when we need to supplement a plant's diet through fertilization.
Organic materials such as manures, compost and bone meal contain these nutrients, but they may not be present in a desirable ratio. Plus direct application of some materials such as dried blood and manure (which should never be used fresh on food gardens) may burn plant roots. That's why many gardeners use commercial fertilizers.
Fertilization should be based upon soil test results, plant age, type of plant and its growth rate and general guidelines often provided by the nursery where you purchased your plant. Rainfall and soil type also should have a bearing on whether to fertilize. During periods of dry weather such as we've experienced in Steamboat this summer, less fertilizer should be used because it encourages water-demanding new growth and can injure roots of drought-stressed plants. Excess nitrogen on dry sites also can burn grasses and other plants. Newly installed plants should receive only a very light application of fertilizer because they are already under stress from the transplant.
You might be so impressed by the results of using a commercial fertilizer that you're tempted to apply more than recommended by the label. Don't! Too much fertilizer can be as harmful to your plants as too little or none at all. Overfertilized plants are more attractive to insects and more likely to succumb to diseases. Over applications of Nitrogen will produce more foliage and less flowering and fruit set. Plus you run the risk of polluting ground and surface water. Apply only the nutrients you need and only in the amounts needed.
Deb Babcock is a Master Gardener through the Colorado State University Cooperative Extension office in Routt County. Questions? Call the CSU Cooperative Extension office at 879-0825 or e-mail to: firstname.lastname@example.org.