By: Sherri Morgan
Garden club members participated in this discussion by stating which plants they fertilize in their own gardens, among those named were: Annual Vegetables, Flowering Shrubs, such as roses and rhododendrons, Lawns, Perennials (especially when first planted and after division), Fruit Trees and Container Plants.
The Big “3” Explained
Nitrogen, phosphorus and potassium, (NPK) are the “Big 3” primary nutrients in commercial fertilizers. These numbers indicate the percentages of Nitrogen, Phosphorus and Potassium by weight in the package. A mnemonic for remembering what each element contributes to plant health is:
UP (N) Nitrogen – Nitrogen is considered to be the most important nutrient as it promotes leaf growth and color, plus it is essential in the formation of protein.
DOWN (P) Phosphorus – Phosphorus promotes root growth, and when in
the form of Phosphoric acid, it helps plants set flower buds. Phosphorus also helps plants with the process of photosynthesis as well as storing energy.
ALL AROUND (K) Potassium – Potassium strengthens a plant’s ability to resist diseases. It helps produce sturdy stems, strong roots, and promotes growth.
There are many different types of fertilizers, both organic, non-organic: Bulb Food, Orchid Food, Acid Fertilizers, and Balanced Fertilizers, to name a few. Each package has its own instructions explaining which plants benefit from that particular fertilizer, and includes how much to apply and how often. Sherri empathized, “Read the label; follow the directions for amount and frequency; more is not better!”
Plants do not always need “feeding” every year, it depends on your soil and its health. For instance, clay soil holds on the nutrients better than decompose granite. A good system for fertilizing is:
- Apply at the beginning, and then again midway through a growth cycle. Exception for rhododendrons: a member suggested rodies should be fertilized after then bloom.
- Apply more frequently to rapidly growing vegetables, such as tomatoes, and for container plants, where the nutrients leach out with each watering.
Compost – Compost is nature’s way of fertilizing. Decayed organic matter, especially in the end, forms humus, which feeds microorganisms that in turn feed the plant. Leaving your leaves on the ground around trees and shrubs will help them grow well.
Organic Fertilizer – Sherri was asked whether using organic fertilizers was important, considering they cost more, and are “slower-acting” than synthetic fertilizers. She stated the energy used to produce synthetic fertilizers is high, plus synthetic fertilizers can damage soil health by salt build-up. They also cause environmental damages when they leach into rivers and the ocean, and into drinking water. Studies have linked overuse of synthetic fertilizers to dead zones in the oceans, increases in certain types of cancer, and birth defects.
Organic fertilizers are derived from organic materials, such as blood meal, kelp meal, bone meal, etc. These feed the soil microorganisms and help improve soil health. They stay attached to soil particles, so they are longer lasting, and their action is more like what would occur in nature.
Fertilizers are only accessible to plants when broken down by soil microorganisms, and when in solution, so it is important to water your plants before, during and after using fertilizer.
BIO: Sherri Morgan is a Landscape Designer and Master Gardener. She is a member of the Ashland Garden Club and past president of the Jackson County Master Gardeners Association. Sherri also teaches in the practicum portion of JCMG classes and designed of the fertilizer curriculum.
